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Choline deficiency: A cause of hepatic steatosis during parenteral nutrition that can be reversed with intravenous choline supplementation
Choline Deficiency: A Cause of Hepatic Steatosis During Parenteral Nutrition That Can Be Reversed With Intravenous Choline Supplementation ALAN L. BUCHMAN,~ MARK D. DUBIN,2 ADIB A. MOUKARZEL,3 DONALD J. JENDEN, 4'5 MARGARETH ROCH,4 KATHLEEN M. RICE,4 JEFF GORNBEIN, 5 AND MARVIN E. AMENT6
P a t i e n t s r e c e i v i n g long-term total p a r e n t e r a l nutrition (TPN) d e v e l o p h e p a t i c steatosis as a c o m p l i c a t i o n . Our p r e v i o u s studies h a v e s h o w n this to be caused, at least in part, by c h o l i n e deficiency. We s t u d i e d f o u r patients (1 man, 3 w o m e n ) a g e d 50 +_ 13 years w h o h a d l o w plasma-free c h o l i n e c o n c e n t r a t i o n s 4.8 _+ 1.7 (normal, 11.4 _+ 3.7 nmol/mL). The p a t i e n t s h a d r e c e i v e d T P N for 9.7 -+ 4.7 years. T h e y r e c e i v e d p a r e n t e r a l n u t r i t i o n solut i o n s c o n t a i n i n g c h o l i n e c h l o r i d e (1 to 4 g/d) for 6 w e e k s . A b d o m i n a l c o m p u t e d t o m o g r a p h y (CT) w a s p e r f o r m e d at baseline, b i w e e k l y d u r i n g t h e c h o l i n e s u p p l e m e n t a tion, a n d 4 w e e k s after d i s c o n t i n u a t i o n o f choline. During c h o l i n e a d m i n i s t r a t i o n , t h e plasma-free c h o l i n e conc e n t r a t i o n i n c r e a s e d into t h e n o r m a l r a n g e w i t h i n 1 w e e k in all four p a t i e n t s a n d r e m a i n e d at or a b o v e t h e n o r m a l r a n g e for all 6 w e e k s , but d e c r e a s e d b a c k to base. line w h e n c h o l i n e s u p p l e m e n t a t i o n w a s d i s c o n t i n u e d . H e p a t i c steatosis r e s o l v e d completely, as e s t i m a t e d by CT. Liver d e n s i t y i n c r e a s e d f r o m - 14.2 _+2 2 ~ H o u n s f i e l d units (HU) to 8.4 +- 10.3 H U at w e e k 2 (P = .002); 9.6 _+ 10.7 H U at w e e k 4 a n d 13.1 +- 7 ~ HU at w e e k 6, as d e t e r m i n e d by t h e liver-spleen CT n u m b e r difference o b t a i n e d by t h e s u b t r a c t i o n o f t h e a v e r a g e s p l e e n CT n u m b e r (in HU) f r o m t h e a v e r a g e liver CT n u m b e r . This i m p r o v e m e n t c o n t i n u e d u p to 4 w e e k s after c h o l i n e supp l e m e n t a t i o n (13.8 + 2.8 HID. Hepatic steatosis w a s s h o w n to h a v e r e c u r r e d in o n e patient after 10 w e e k s o f r e t u r n to choline-free p a r e n t e r a l nutrition. The h e p a t i c steatosis a s s o c i a t e d w i t h p a r e n t e r a l n u t r i t i o n c a n be
ameliorated, a n d possibly prevented, w i t h c h o l i n e supp l e m e n t a t i o n . Therefore, c h o l i n e m a y be an e s s e n t i a l nutrient for p a t i e n t s w h o require long-term p a r e n t e r a l nutrition. (HEPATOLOGY1995;22:1399-1403.) We h a v e p r e v i o u s l y s h o w n t h a t p a t i e n t s receiving l o n g - t e r m total p a r e n t e r a l n u t r i t i o n (TPN) develop choline deficiency. 1'2 This deficiency is m a n i f e s t e d in hepatic steatosis, e P l a s m a - f r e e choline c o n c e n t r a t i o n is less t h a n n o r m a l in u p w a r d s of 80% of h o m e T P N patients. 1 I n a previous study, we f o u n d t h a t oral lecithin s u p p l e m e n t a t i o n c a u s e d a n increase in p l a s m a - f r e e choline a n d a decrease in the h e p a t i c steatosis. 2 However, p l a s m a - f r e e choline c o n c e n t r a t i o n s still r e m a i n e d below n o r m a l because t h e lecithin w a s poorly absorbed. I n addition, t a s t e tolerance to the lecithin solution w a s poor. Therefore, we developed a n i n t r a v e n o u s (IV) choline f o r m u l a t i o n t h a t would c i r c u m v e n t t h e s e two problems. This s t u d y w a s u n d e r t a k e n to d e t e r m i n e if IV choline chloride would lead to n o r m a l i z a t i o n of p l a s m a free choline a n d r e s o l u t i o n of h e p a t i c steatosis in choline-deficient h o m e T P N patients. The p h a r m a c o k i netic i n f o r m a t i o n for IV choline chloride in h u m a n subjects w a s derived in a previous study. 3 P A T I E N T S AND M E T H O D S
Subjects. Four subjects, who were known to have low plasma-free choline concentration and hepatic steatosis from Abbreviations:TPN, total; IV, intravenous; CT, computedtomography;AST, our previous investigations, were studied. These included aspartate transaminase; ALT,alanine transaminase; HU, Hounsfieldunits. three women aged 45, 50, and 72 years and one man aged 43 Fromthe 1SectionofGastroenterology,BaylorCollegeofMedicine, Houston, years. Two subjects had short bowel syndrome from Crohn's TX; 2Departmentof Radiology,UCLAMedical Center, Los Angeles,CA; 3Divi- disease, one had radiation enteritis, and the fourth had sion of Pediatrics, Maimonides Medical Center, New York, NY; 4Department of Pharmacology,UCLASchoolof Medicine, Los Angeles,CA; ~Department of chronic intestinal pseudo-obstruction. The subjects had reBiomathematics, UCLASchoolof Medicine, Los Angeles,CA; and eDivisionof ceived home TPN for 9.7+_4.7 years (range, 3.5 to 13.5 yrs). Their TPN consisted of 2 to 3 L of 15% to 25% dextrose soluPediatric Gastroenterology,UCLAMedical Center, Los Angeles,CA. tion with 3% to 3.5% amino acids, electrolytes, trace eleReceived December16, 1994;acceptedJune 1.3, 1995. Supported by Caremark, Inc, Minneapolis, MN, and United States Public ments, and vitamins. All subjects received 19.5+_3.7 kcal/kg/ Health ServiceRR-00865. d actual body weight (range, 16 to 24 kcal/kg/d). This level of Presented in part at the AmericanGastroenterologicalAssociationAnnual support varied between subjects depending upon individual Meeting, Boston,MA, May 16, 1993;and the AmericanSocietyfor Parenteral variation in oral intake and intestinal absorption. Intraveand Enteral Nutrition Annual Meeting, San Diego,CA, February 14, 1993. nous lipid (Intralipid 20%; Kabi Vitrum, Alameda, CA) supAddressreprint requests to: AlanL. Buchman,MD, MSPH,SectionofGastroenterology, Baylor Collegeof Medicine, 6550 Fannin, SM 1122, Houston, plied 42.5% _+ 25.7% of daily IV caloric intake (Table 2). No adjustments in TPN were made during the study. The TPN TX 77030. Copyright © 1995 by the American Association for the Study of Liver solution included 2.3 to 5 g/d of methionine depending on the total amino acid concentration (3% to 3.5%). The vitamin Diseases. 0270-9139/95/2205-000953.00/0 preparation included 5 #g vitamin B12 and 400 ~g folate on 1399
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BUCHMAN ET AL
a daily basis. All subjects received their TPN nightly over 10 to 12 hours. Approval for the study was granted by the Food and Drug Administration, and informed consent approved by the UCLA H u m a n Subjects Protection Committee was given by all enrolled subjects. Plasma-free choline concentration was serially measured in a group of eight normal volunteers receiving TPN as an exclusive means of nutritional support, as part of another study2 Study Design. The subjects were supplied with 42 singledose vials containing 10 g choline chloride. Details concerning the preparation of choline chloride that was used in TPN solutions are supplied in a previous publication. 4 The four subjects were prescribed 1 to 4 g of choline chloride in the TPN solution each night based on our previous pharmacokinetic data 4 (Table 2). The subjects withdrew the appropriate amount of choline chloride each night and injected it into their TPN bag. Previous data have shown that choline chloride in doses as high as 10 g/L is stable for at least 30 days and does not affect the pH or amino acid availability of the TPN solution (Buchman et al, Unpublished observations, 1992). Choline recovery was 93% to 102%. The patients were examined at baseline, weekly for 6 weeks during the choline infusion, and again 4 weeks after the discontinuation of the choline-supplemented TPN. Plasma free choline concentration, serum aspartate transaminase (AST), alanine transaminase (ALT), and total cholesterol concentrations were obtained at each visit. Plasma-free choline was measured by gas chromatography and mass spectrometry. ~'6 Serum transaminase activities and total cholesterol concentrations were determined using standard automated techniques. Plasma phospholipid-bound choline was measured at baseline, at the end of the 6 week nightly choline infusion and 4 weeks later. The method involved extraction as described by Folch et al 7 and hydrolysis as described by Jope and Jenden. s All blood samples were obtained after the subjects had fasted overnight, and 3 to 5 hours after completion of their nightly TPN. Computed tomography (CT) was used as a noninvasive method for estimation of hepatic fat content. This was performed at baseline, every 2 weeks during the choline infusion, and again at 4 weeks (patients no. 1 to 3) or 10 weeks (patient no. 4) after the discontinuation of choline-supplemented TPN, using methodology described by us and others. 9-14 Limited noncontrast CT scans of the liver and spleen were obtained using a GE 9800 CT scanner (Milwaukee, WI). Multiple contiguous 1-cm axial sections at 1-cm intervals were obtained through the upper abdomen. Attenuation values (CT numbers in Hounsfield units [HU]) for regions of interest in the liver and spleen were generated from multiple representative sections. The average (mean) CT number (in HU) were then calculated for each organ. Liver density was determined using two currently acceptable methods: (1) the average absolute liver CT number, and (2) the liver-spleen CT number difference obtained by the subtraction of the average spleen CT number from the average liver CT number (to correct for interscan variability). In the normal state, the liver and spleen maintain a fairly constant relationship in terms of relative CT numbers on noncontrast scans. Fat has a distinctly low CT number in HU. In hepatic steatosis, liver attenuation is diminished, which is reflected by a low CT number (in HU), whereas spleen attenuation remains constant. On the main scanner used at our institution, normal liver density corresponds to approximately 45 HU in absolute terms, and normal liver attenuation values exceed those of the spleen by approximately 8 HU
HEPATOLOGYNovember 1995 (i.e., a liver-spleen CT number difference of approximately +8 HU). Therefore, liver density and hepatic steatosis are inversely related. Fatty liver was defined as an absolute CT number _+45 HU, or a liver-spleen CT number difference of +8.0 HU (with 0 to 8 HU representing borderline fatty infiltration and _+0 HU corresponding to marked fatty infiltration). Data were analyzed by comparing baseline values with subsequent data points using paired t-tests or ANOVA where appropriate. Data are presented as mean _+ SD and a P < .05 constituted statistical significance. RESULTS All four p a t i e n t s h a d low p l a s m a - f r e e choline concent r a t i o n s a t t h e b e g i n n i n g of t h e s t u d y (5.2 __ 2.1; r a n g e , 2.7 to 7.2; n o r m a l ; 11.4 ± 3.7 nmo]/mL). T h e full 10w e e k s t u d y w a s c o m p l e t e d b y all four subjects. One subject ( p a t i e n t no. 2) m i s t a k e n l y received a CT s c a n a t 5 weeks; b e l i e v i n g t h a t to be t h e e n d of t h e study, s h e did not infuse choline w i t h h e r T P N d u r i n g t h e 6 t h week. T h i s subject also r e q u i r e d two dose a d j u s t m e n t s in t h e choline chloride b e c a u s e of m i l d n a u s e a occ u r r i n g u p o n a w a k e n i n g in t h e m o r n i n g a t t h e e n d of t h e choline infusion. H e r dose w a s d e c r e a s e d f r o m 2 g/ d to 1 g/d on d a y 10, a n d t h e n to 1 g e v e r y o t h e r d a y on d a y 24 u n t i l it w a s i n c r e a s e d b a c k to 1 g/d on d a y 30 (the p a t i e n t did not c o m p l a i n of n a u s e a for t h e rem a i n d e r of t h e study). D u r i n g t h e p h a r m a c o k i n e t i c s s t u d i e s p r e c e d i n g t h i s 6 - w e e k choline infusion study, this p a t i e n t t o l e r a t e d p l a s m a - f r e e choline level as h i g h as 230 n m o Y m L w i t h o u t a n y side effects. B e c a u s e this p a t i e n t h a s a h i s t o r y of e a r l y m o r n i n g h e a d a c h e s t h a t w e r e a t one t i m e a s s o c i a t e d w i t h lipid e m u l s i o n , it is u n c l e a r w h e t h e r t h e choline w a s r e s p o n s i b l e for t h e n a u s e a . No o t h e r subject e x p e r i e n c e d a n y side effects or r e q u i r e d a dose a d j u s t m e n t . Subjectively, t h e p a t i e n t s r e p o r t e d no c h a n g e in d i e t a r y h a b i t s or i n t a k e d u r i n g t h e study. No p a t i e n t h a d evidence of m a l n u t r i t i o n before or d u r i n g t h e study. W e e k l y p l a s m a - f r e e choline c o n c e n t r a t i o n s for e a c h subject a r e s h o w n in T a b l e 2. P l a s m a - f r e e choline conc e n t r a t i o n i n c r e a s e d into t h e n o r m a l r a n g e or g r e a t e r (normal, 11.4 _+ 3.7 n m o l / m L ) in all subjects a f t e r 1 w e e k of choline chloride s u p p l e m e n t a t i o n . H e p a t i c s t e a t o s i s d e c r e a s e d significantly in all four subjects a t t h e t i m e of t h e initial follow-up CT scan, w h i c h w a s o b t a i n e d 2 w e e k s a f t e r choline chloride s u p p l e m e n t a tion w a s i n i t i a t e d (Table 1). T h i s w a s i n d i c a t e d b y a
TABLE 1. H e p a t i c D e n s i t y a s E s t i m a t e d b y t h e L i v e r - S p l e e n C T N u m b e r D i f f e r e n c e (in H U ) Patient No.
Baseline
2 wk
4 wk
6 wk
4 wk After Choline
-3.9 19.8 13.2 4.5
-3.8 19.2 17.2 5.6
3.3 15.4 20.8 12.8
10.6 15.7 15.0 -6.3*
1
-47.0
2
-0.7
3 4
0.3 -9.4
* 10 weeks after choline supplementation indicating return of hepatic steatosis.
HEPATOLOGYVol. 22, No. 5, 1995
BUCHMAN ET AL
marked increase in liver density. The CT number difference yielded by the liver-spleen subtraction method improved by an average 20 _+ 16.5 HU (-14.2 +_ 22.3 to 8.4 _+ 10.3 HU; P = .002). As in our previous study, changes in absolute liver CT numbers correlated well with changes in the the liver-spleen CT number difference (r = .98). Hepatic steatosis continued to decrease during the 6 weeks of choline chloride supplementation and completely resolved in all four subjects. On concurrent scans the liver and spleen densities assumed a normal, or near-normal relationship. Although plasmafree choline concentrations were similar to their baseline values 4 weeks after choline chloride was discontinued, hepatic steatosis had not yet returned on the postsupplementation CT scans. Because of missed appointments, patient no. 4 was examined 10 weeks after the 6 weeks of choline chloride supplemented TPN had been discontinued. Her hepatic steatosis had recurred by that time (Table 1). Liver density appeared identical to the baseline CT scan, and the liver-spleen CT number difference returned to a negative value, as it had been at baseline. Serum AST and ALT activities are shown in Figs. 1 and 2. They showed no significant change during the study except for subject no. 1, who also had the most striking hepatic steatosis at baseline and the greatest relative increase in hepatic CT attenuation steatosis during the study (Table 1; Fig. 3). At baseline, three of the four subjects had normal AST, and two had normal serum ALT activity (Figs. 1 and 2). No change in total serum cholesterol or plasma phospholipid-bound choline was observed during the study (Fig. 4). Plasma-free choline decreased in the normal volunteers after 1 week of choline-free TPN (Table 2).
DISCUSSION In our previous study, we found a significant negative correlation between liver-fat density and plasma-
I- ~- Subject --B--Subject1 2 80 70 60 50 ALT 40
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Week Fig. 1. Serum ALT activities before, during, and after choline chloride supplementation (normal, 5 to 50 U/L).
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Week Fig. 2. Serum AST activities before, during, and after choline chloride supplementation (normal, 5 to 40 U/L).
free choline concentration, even when the plasma-free choline level remained below normal. 2 Our current study shows that hepatic steatosis associated with long-term TPN, is probably caused by choline deficiency in the absence of overfeeding or fatty acid deficiency and/or protein deficiency. The steatosis can be ameliorated with choline-supplemented TPN. We and others have shown that plasma-free choline concentration is low in nearly all patients who receive long-term TPN. 1'2'15'16 The prevalence of hepatic steatosis in patients who receive parenteral nutrition is difficult to ascertain. Our previous data 2 along with studies by Host et a117 and Grant et al is suggest this figure is approximately 50% to 60%. Shapiro et a115 also observed a decrease in hepatic steatosis in one patient, who required TPN because of severe protein calorie malnutrition after supplementation with orally administered choline, in addition to tyrosine, cyst(e)ine and carnitine. One patient had no steatosis before supplementation, but it developed subsequent to the initiation of TPN and the oral supplements. However, because their patients were extremely malnourished, it was unclear if the hepatic steatosis in the former patient was related to protein malnutrition and/or fatty acid deficiency. Resolution may have occurred after improvement in his overall nutritional status. No calorie, lipid, or protein intake information was provided for the second patient. It is possible that rapid overfeeding led to the development of hepatic steatosis independent of choline status. Plasma-free choline concentrations decreased within 1 week, even in well-nourished normal volunteers who were provided with TPN as an exclusive source of nutritional support (Table 2). Therefore, choline should probably be provided in the solutions of all patients receiving long-term TPN. Our current study confirms data from our previous study 2 that showed serum transaminase activities are
1402
BUCHMAN ET AL
HEPATOLOGYNovember 1995
I-
Subject - - B - 1
Subject2
- Subject 3
-- &-- Subject I I
4
I
240
Cholesterol
mg/dl
200,
"'--X"
160
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120
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8o, 40
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2
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4
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Week Fig. 4. Plasma lipid-bound choline concentrations before and after choline chloride supplementation.
Fig. 3. (A) Liver CT scan before choline chloride supplementation (patient no. 1) showing marked hepatic steatosis (-47.0). (B) Liver CT scan after 2 weeks of choline chloride supplementation (patient no. 1) showing hepatic steatosis (-3.9 HU). (C) Liver CT scan after 6 weeks of choline chloride supplementation (patient no. 1) showing no hepatic steatosis (3.3 HU).
both insensitive and nonspecific indicators of changes in the degree of hepatic steatosis. Many patients who require TPN may develop unrecognized hepatic steatosis, because they do not manifest serum hepatic transaminase elevations. In addition, as we have previously shown, 1 transaminase increases in patients that receive TPN are not necessarily caused by hepatic steatosis; drugs, chronic hepatitis, and other factors may also contribute. Lipid emulsions such as Intralipid (Clintec, Deerfield, IL) contain some choline, primarily in the form of phosphatidylcholine, but our pre~i~us study, 2 as well as work by Sheard et al, 16 have shown this amount to be small. They contain very little free choline. Choline should be synthesized from the methionine contained in TPN solutions. However, the intravenous delivery of nutrients bypasses the portal system, and the firstpass effect of dietary choline through the liver. Therefore, we speculate IV methionine is probably not metabolized to choline and the low but detectable plasma choline concentrations in our subjects probably reflect some, albeit minimal, dietary methionine and choline absorption. Shapiro et a115 have also suggested low plasma choline concentrations may be related to a defective hepatic transsulfuration pathway on the basis of low plasma choline, carnitine, cyst(e)ine, and tyrosine concentrations in their two patients who required TPN for severe protein calorie malnutrition. That is probably the explanation for the finding of increased normal to elevated plasma methionine concentrations in home TPN p . a t i ~ r ~ ' s f i ' 1 ~ ' ~ ...... Deficient phosphatidylcholine may result in an inability of the liver to transport triglyceride as part of lipoproteins. 21We cannot explain why hepatic steatosis occurs despite normal plasma phospholipid-bound choline concentration. A previous study, 2 as well as our current study, has shown the degree of hepatic steatosis is correlated only with plasma-free choline
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TABLE 2. I n t r a v e n o u s C h o l i n e , L i p i d E m u l s i o n D o s a g e , a n d P l a s m a - F r e e C h o l i n e C o n c e n t r a t i o n i n C h o l i n e - D e f i c i e n t Patients and Normal Volunteers Receiving TPN
Patient No.
Choline Chloride (g/d)
Intralipid 20% (mL/d)
Plasma Free Choline (nmol/mL) Baseline
Week 1
Week 2
Week 3
Week 4
Week 5
Week 6
Week 10"
1 2 3 4 Normal volunteers (n = 8)
4 2 3 3 0
428 34 84 112 462 _+ 63
5.2 7.4 6.6 3.7 9.4 _+ 0.4
19.7 54.5 36.2 33.6 7.7 _+ 0.8
20.2 16.9 23.0 38.1 7.6 + 0.5
27.9 16.3 21.1 40.5 N/A
7.3 10.6 26.6 28.5 N/A
18.2 26.1 32.6 40.8 N/A
19.7 5.9* 21.1 27.6 N/A
3.8 8.9 N/A 6.6 N/A
Abbreviation: N/A, not available. * Choline discontinued.
concentration. It is possible that plasma phosphatidyl choline is not transported into hepatocytes or that a blockage exists in the metabolism of phosphatidylcholine to free choline. Choline elimination is a function of tissue uptake and metabolism as well as urinary excretion. 4 The choline dose should be adjusted in patients with impaired hepatic and/or renal function. 4 However, as indicated in our present study, a plateau is reached at which time plasma-free choline concentrations do not continue to increase, although they m a y vary from week to week (Table 2). We would recommend that the plasma choline level be monitored weekly or biweekly until a plateau level in the normal range is achieved. Choline levels should therefore be monitored, as should any other nutrient such as potassium, zinc, and so on, added to the TPN solution. In conclusion, choline m a y be an essential nutrient in patients with minimal oral intake or absorption. Choline deficiency results in hepatic steatosis that may be reversed by the addition of choline to TPN solutions. Because the addition of choline to TPN solutions ameliorates hepatic steatosis, it is likely that choline supplementation at initiation of TPN will prevent or blunt the development of hepatic steatosis. Our data are preliminary, but suggest the need for larger, randomized, controlled clinical trials of choline-supplemented TPN in the treatment and prevention of TPN-associated liver disease.
6. 7. 8. 9.
10.
11. 12.
13. 14. 15.
16. REFERENCES
1. Buchman AL, Moukarzel AA, Jenden DJ, Roch M, Rice K, Ament ME, et al. Hepatic transaminase abnormalities are associated with low plasma free choline in patients receiving long-term parenteral nutrition. Clin Nutr 1993;12:38-42. 2. Buchman AL, Dubin M, Jenden D, Moukarzel A, Roch MH, Rice K, Gornbein J, et al. Lecithin increases plasma free choline and decreases hepatic steatesis in long-term total parenteral nutrition patients. Gastroenterology 1992;102:1363-1370. 3. Buchman AL, Moukarzel AA, Eckhert C, Ament ME, Eckhert C, Bhuta S, Mestecky J, et al. The effects of TPN on intestinal morphology and function in man. Transplant Proc 1994; 26:1457. 4. Buchman AL, Jenden DJ, Moukarzel AA, Roch M, Rice KM, Chang AS, Ament ME. Choline pharmacokinetics during intermittent choline infusion in humans. Clin Pharmacol Ther 1994;55:277-283. 5. Jenden DJ, Roch M, Booth RA. Simultaneous measurement of
17. 18.
19. 20.
21.
endogenous and deuterium-labeledtracer variants of choline and acetylcholine in subpicomole quantities by gas chromatography spectrometry. Anal Biochem 1973;55:438-448. Freeman JJ, Choi RL, Jenden DJ. Plasma choline: its turnover and exchange with brain choline. J Neurochem 1975;24:729-734. Folch J, Lees M, Stanley GHS. A simple method for the isolation and purification of total lipids from animal tissue. J Bio Chem 1957;226:497-509. Jope RS, Jenden DJ. Choline and phospholipid metabolism and the synthesis of acetylcholine in rat brain. J Neurosci Res 1979;4:69-82. Ducommon J, Goldberg HI, Royal SA, Koroblein M, Moss AA, Kressel HY, et al. The relation of fatty liver to computed tomography numbers: a preliminary experimental study in rabbits. Radiology 1979;130:511-513. Peikarski J, Goldberg HI, Royal SA, Axel L, Moss AA. Differences between liver and spleen CT numbers in the normal adult: its usefulness in predicting the presence of diffuse liver disease. Radiology 1980;137:727-729. Bydder GM, Chapman RW, Harry D, et al. Computed tomography attenuation values in fatty liver. J Comp Tomo 1981;5:3335. Yajima Y, Naruri T, Motoyasu I, Abe R, Ohtsuki M, Goto Y, Endo S, et al. Computed tomography in the diagnosis of fatty liver: total lipid content and computed temography number. Tohoku J Exp Med 1982;136:337-342. Bashist B, Hecht HL, Harley WD. Computed tomographic demonstration of rapid changes in fatty infiltration of the liver. Radiology 1982;142:691-692. Goodacre RL, Hunter DJ, Millward S, Pirani M, Riddell RH. The diagnosis of acute fatty liver of pregnancy by computerized tomography. J Clin Gastroenterol 1988;10:680-682. Shapiro G, Chawla RK, Berry CJ, Williams PJ, Roy RGB, Rudmen D. Cysteine, tyrosine, choline and carnitine supplementation of patients on total parenteral nutrition. Nutr Int 1986;2:334-339. Sheard NF, Tayek JA, Bistrian BR, Blackburn GL, Zeisel SH. Plasma choline concentrations in humans fed parenterally. Am J Clin Nutr 1986;43:219-224. Host WR, Serlin O, Rush BF. Hyperalimentation in cirrhotic patients. Am J Surg 1972;123:57-56. Grant JP, Cox CE, Kleinman LM, Maher MM, Pittman MA, Tangrea JA, Brown JH, et al. Serum hepatic enzymes and bilirubin elevations during parenteral nutrition. Surg Gynecol Obstet 1977;145:573-580. Dahlstrom KA, Ament ME, Laidlaw SA, Kopple JD. Plasma amino acid concentrations in children receiving long-term parenteral nutrition. J Pediatr Gastroenterol Nutr 1988;7:748-754. Chawla RK, Berry CJ, Kutner MH, Rudman D. Plasma concentrations of transsulfuration pathway products during nasoenteral and intravenous hyperalimentation of malnourished patients. Am J Clin Nutr 1985;42:577-584. Zeisel SH. Vitamin-like molecules. In: Shils ME, Young VR, eds. Modern nutrition in health and disease. Ed 7th. Philadelphia: Lee and Farber, 1988:440-452.
P a t i e n t s r e c e i v i n g long-term total p a r e n t e r a l nutrition (TPN) d e v e l o p h e p a t i c steatosis as a c o m p l i c a t i o n . Our p r e v i o u s studies h a v e s h o w n this to be caused, at least in part, by c h o l i n e deficiency. We s t u d i e d f o u r patients (1 man, 3 w o m e n ) a g e d 50 +_ 13 years w h o h a d l o w plasma-free c h o l i n e c o n c e n t r a t i o n s 4.8 _+ 1.7 (normal, 11.4 _+ 3.7 nmol/mL). The p a t i e n t s h a d r e c e i v e d T P N for 9.7 -+ 4.7 years. T h e y r e c e i v e d p a r e n t e r a l n u t r i t i o n solut i o n s c o n t a i n i n g c h o l i n e c h l o r i d e (1 to 4 g/d) for 6 w e e k s . A b d o m i n a l c o m p u t e d t o m o g r a p h y (CT) w a s p e r f o r m e d at baseline, b i w e e k l y d u r i n g t h e c h o l i n e s u p p l e m e n t a tion, a n d 4 w e e k s after d i s c o n t i n u a t i o n o f choline. During c h o l i n e a d m i n i s t r a t i o n , t h e plasma-free c h o l i n e conc e n t r a t i o n i n c r e a s e d into t h e n o r m a l r a n g e w i t h i n 1 w e e k in all four p a t i e n t s a n d r e m a i n e d at or a b o v e t h e n o r m a l r a n g e for all 6 w e e k s , but d e c r e a s e d b a c k to base. line w h e n c h o l i n e s u p p l e m e n t a t i o n w a s d i s c o n t i n u e d . H e p a t i c steatosis r e s o l v e d completely, as e s t i m a t e d by CT. Liver d e n s i t y i n c r e a s e d f r o m - 14.2 _+2 2 ~ H o u n s f i e l d units (HU) to 8.4 +- 10.3 H U at w e e k 2 (P = .002); 9.6 _+ 10.7 H U at w e e k 4 a n d 13.1 +- 7 ~ HU at w e e k 6, as d e t e r m i n e d by t h e liver-spleen CT n u m b e r difference o b t a i n e d by t h e s u b t r a c t i o n o f t h e a v e r a g e s p l e e n CT n u m b e r (in HU) f r o m t h e a v e r a g e liver CT n u m b e r . This i m p r o v e m e n t c o n t i n u e d u p to 4 w e e k s after c h o l i n e supp l e m e n t a t i o n (13.8 + 2.8 HID. Hepatic steatosis w a s s h o w n to h a v e r e c u r r e d in o n e patient after 10 w e e k s o f r e t u r n to choline-free p a r e n t e r a l nutrition. The h e p a t i c steatosis a s s o c i a t e d w i t h p a r e n t e r a l n u t r i t i o n c a n be
ameliorated, a n d possibly prevented, w i t h c h o l i n e supp l e m e n t a t i o n . Therefore, c h o l i n e m a y be an e s s e n t i a l nutrient for p a t i e n t s w h o require long-term p a r e n t e r a l nutrition. (HEPATOLOGY1995;22:1399-1403.) We h a v e p r e v i o u s l y s h o w n t h a t p a t i e n t s receiving l o n g - t e r m total p a r e n t e r a l n u t r i t i o n (TPN) develop choline deficiency. 1'2 This deficiency is m a n i f e s t e d in hepatic steatosis, e P l a s m a - f r e e choline c o n c e n t r a t i o n is less t h a n n o r m a l in u p w a r d s of 80% of h o m e T P N patients. 1 I n a previous study, we f o u n d t h a t oral lecithin s u p p l e m e n t a t i o n c a u s e d a n increase in p l a s m a - f r e e choline a n d a decrease in the h e p a t i c steatosis. 2 However, p l a s m a - f r e e choline c o n c e n t r a t i o n s still r e m a i n e d below n o r m a l because t h e lecithin w a s poorly absorbed. I n addition, t a s t e tolerance to the lecithin solution w a s poor. Therefore, we developed a n i n t r a v e n o u s (IV) choline f o r m u l a t i o n t h a t would c i r c u m v e n t t h e s e two problems. This s t u d y w a s u n d e r t a k e n to d e t e r m i n e if IV choline chloride would lead to n o r m a l i z a t i o n of p l a s m a free choline a n d r e s o l u t i o n of h e p a t i c steatosis in choline-deficient h o m e T P N patients. The p h a r m a c o k i netic i n f o r m a t i o n for IV choline chloride in h u m a n subjects w a s derived in a previous study. 3 P A T I E N T S AND M E T H O D S
Subjects. Four subjects, who were known to have low plasma-free choline concentration and hepatic steatosis from Abbreviations:TPN, total; IV, intravenous; CT, computedtomography;AST, our previous investigations, were studied. These included aspartate transaminase; ALT,alanine transaminase; HU, Hounsfieldunits. three women aged 45, 50, and 72 years and one man aged 43 Fromthe 1SectionofGastroenterology,BaylorCollegeofMedicine, Houston, years. Two subjects had short bowel syndrome from Crohn's TX; 2Departmentof Radiology,UCLAMedical Center, Los Angeles,CA; 3Divi- disease, one had radiation enteritis, and the fourth had sion of Pediatrics, Maimonides Medical Center, New York, NY; 4Department of Pharmacology,UCLASchoolof Medicine, Los Angeles,CA; ~Department of chronic intestinal pseudo-obstruction. The subjects had reBiomathematics, UCLASchoolof Medicine, Los Angeles,CA; and eDivisionof ceived home TPN for 9.7+_4.7 years (range, 3.5 to 13.5 yrs). Their TPN consisted of 2 to 3 L of 15% to 25% dextrose soluPediatric Gastroenterology,UCLAMedical Center, Los Angeles,CA. tion with 3% to 3.5% amino acids, electrolytes, trace eleReceived December16, 1994;acceptedJune 1.3, 1995. Supported by Caremark, Inc, Minneapolis, MN, and United States Public ments, and vitamins. All subjects received 19.5+_3.7 kcal/kg/ Health ServiceRR-00865. d actual body weight (range, 16 to 24 kcal/kg/d). This level of Presented in part at the AmericanGastroenterologicalAssociationAnnual support varied between subjects depending upon individual Meeting, Boston,MA, May 16, 1993;and the AmericanSocietyfor Parenteral variation in oral intake and intestinal absorption. Intraveand Enteral Nutrition Annual Meeting, San Diego,CA, February 14, 1993. nous lipid (Intralipid 20%; Kabi Vitrum, Alameda, CA) supAddressreprint requests to: AlanL. Buchman,MD, MSPH,SectionofGastroenterology, Baylor Collegeof Medicine, 6550 Fannin, SM 1122, Houston, plied 42.5% _+ 25.7% of daily IV caloric intake (Table 2). No adjustments in TPN were made during the study. The TPN TX 77030. Copyright © 1995 by the American Association for the Study of Liver solution included 2.3 to 5 g/d of methionine depending on the total amino acid concentration (3% to 3.5%). The vitamin Diseases. 0270-9139/95/2205-000953.00/0 preparation included 5 #g vitamin B12 and 400 ~g folate on 1399
1400
BUCHMAN ET AL
a daily basis. All subjects received their TPN nightly over 10 to 12 hours. Approval for the study was granted by the Food and Drug Administration, and informed consent approved by the UCLA H u m a n Subjects Protection Committee was given by all enrolled subjects. Plasma-free choline concentration was serially measured in a group of eight normal volunteers receiving TPN as an exclusive means of nutritional support, as part of another study2 Study Design. The subjects were supplied with 42 singledose vials containing 10 g choline chloride. Details concerning the preparation of choline chloride that was used in TPN solutions are supplied in a previous publication. 4 The four subjects were prescribed 1 to 4 g of choline chloride in the TPN solution each night based on our previous pharmacokinetic data 4 (Table 2). The subjects withdrew the appropriate amount of choline chloride each night and injected it into their TPN bag. Previous data have shown that choline chloride in doses as high as 10 g/L is stable for at least 30 days and does not affect the pH or amino acid availability of the TPN solution (Buchman et al, Unpublished observations, 1992). Choline recovery was 93% to 102%. The patients were examined at baseline, weekly for 6 weeks during the choline infusion, and again 4 weeks after the discontinuation of the choline-supplemented TPN. Plasma free choline concentration, serum aspartate transaminase (AST), alanine transaminase (ALT), and total cholesterol concentrations were obtained at each visit. Plasma-free choline was measured by gas chromatography and mass spectrometry. ~'6 Serum transaminase activities and total cholesterol concentrations were determined using standard automated techniques. Plasma phospholipid-bound choline was measured at baseline, at the end of the 6 week nightly choline infusion and 4 weeks later. The method involved extraction as described by Folch et al 7 and hydrolysis as described by Jope and Jenden. s All blood samples were obtained after the subjects had fasted overnight, and 3 to 5 hours after completion of their nightly TPN. Computed tomography (CT) was used as a noninvasive method for estimation of hepatic fat content. This was performed at baseline, every 2 weeks during the choline infusion, and again at 4 weeks (patients no. 1 to 3) or 10 weeks (patient no. 4) after the discontinuation of choline-supplemented TPN, using methodology described by us and others. 9-14 Limited noncontrast CT scans of the liver and spleen were obtained using a GE 9800 CT scanner (Milwaukee, WI). Multiple contiguous 1-cm axial sections at 1-cm intervals were obtained through the upper abdomen. Attenuation values (CT numbers in Hounsfield units [HU]) for regions of interest in the liver and spleen were generated from multiple representative sections. The average (mean) CT number (in HU) were then calculated for each organ. Liver density was determined using two currently acceptable methods: (1) the average absolute liver CT number, and (2) the liver-spleen CT number difference obtained by the subtraction of the average spleen CT number from the average liver CT number (to correct for interscan variability). In the normal state, the liver and spleen maintain a fairly constant relationship in terms of relative CT numbers on noncontrast scans. Fat has a distinctly low CT number in HU. In hepatic steatosis, liver attenuation is diminished, which is reflected by a low CT number (in HU), whereas spleen attenuation remains constant. On the main scanner used at our institution, normal liver density corresponds to approximately 45 HU in absolute terms, and normal liver attenuation values exceed those of the spleen by approximately 8 HU
HEPATOLOGYNovember 1995 (i.e., a liver-spleen CT number difference of approximately +8 HU). Therefore, liver density and hepatic steatosis are inversely related. Fatty liver was defined as an absolute CT number _+45 HU, or a liver-spleen CT number difference of +8.0 HU (with 0 to 8 HU representing borderline fatty infiltration and _+0 HU corresponding to marked fatty infiltration). Data were analyzed by comparing baseline values with subsequent data points using paired t-tests or ANOVA where appropriate. Data are presented as mean _+ SD and a P < .05 constituted statistical significance. RESULTS All four p a t i e n t s h a d low p l a s m a - f r e e choline concent r a t i o n s a t t h e b e g i n n i n g of t h e s t u d y (5.2 __ 2.1; r a n g e , 2.7 to 7.2; n o r m a l ; 11.4 ± 3.7 nmo]/mL). T h e full 10w e e k s t u d y w a s c o m p l e t e d b y all four subjects. One subject ( p a t i e n t no. 2) m i s t a k e n l y received a CT s c a n a t 5 weeks; b e l i e v i n g t h a t to be t h e e n d of t h e study, s h e did not infuse choline w i t h h e r T P N d u r i n g t h e 6 t h week. T h i s subject also r e q u i r e d two dose a d j u s t m e n t s in t h e choline chloride b e c a u s e of m i l d n a u s e a occ u r r i n g u p o n a w a k e n i n g in t h e m o r n i n g a t t h e e n d of t h e choline infusion. H e r dose w a s d e c r e a s e d f r o m 2 g/ d to 1 g/d on d a y 10, a n d t h e n to 1 g e v e r y o t h e r d a y on d a y 24 u n t i l it w a s i n c r e a s e d b a c k to 1 g/d on d a y 30 (the p a t i e n t did not c o m p l a i n of n a u s e a for t h e rem a i n d e r of t h e study). D u r i n g t h e p h a r m a c o k i n e t i c s s t u d i e s p r e c e d i n g t h i s 6 - w e e k choline infusion study, this p a t i e n t t o l e r a t e d p l a s m a - f r e e choline level as h i g h as 230 n m o Y m L w i t h o u t a n y side effects. B e c a u s e this p a t i e n t h a s a h i s t o r y of e a r l y m o r n i n g h e a d a c h e s t h a t w e r e a t one t i m e a s s o c i a t e d w i t h lipid e m u l s i o n , it is u n c l e a r w h e t h e r t h e choline w a s r e s p o n s i b l e for t h e n a u s e a . No o t h e r subject e x p e r i e n c e d a n y side effects or r e q u i r e d a dose a d j u s t m e n t . Subjectively, t h e p a t i e n t s r e p o r t e d no c h a n g e in d i e t a r y h a b i t s or i n t a k e d u r i n g t h e study. No p a t i e n t h a d evidence of m a l n u t r i t i o n before or d u r i n g t h e study. W e e k l y p l a s m a - f r e e choline c o n c e n t r a t i o n s for e a c h subject a r e s h o w n in T a b l e 2. P l a s m a - f r e e choline conc e n t r a t i o n i n c r e a s e d into t h e n o r m a l r a n g e or g r e a t e r (normal, 11.4 _+ 3.7 n m o l / m L ) in all subjects a f t e r 1 w e e k of choline chloride s u p p l e m e n t a t i o n . H e p a t i c s t e a t o s i s d e c r e a s e d significantly in all four subjects a t t h e t i m e of t h e initial follow-up CT scan, w h i c h w a s o b t a i n e d 2 w e e k s a f t e r choline chloride s u p p l e m e n t a tion w a s i n i t i a t e d (Table 1). T h i s w a s i n d i c a t e d b y a
TABLE 1. H e p a t i c D e n s i t y a s E s t i m a t e d b y t h e L i v e r - S p l e e n C T N u m b e r D i f f e r e n c e (in H U ) Patient No.
Baseline
2 wk
4 wk
6 wk
4 wk After Choline
-3.9 19.8 13.2 4.5
-3.8 19.2 17.2 5.6
3.3 15.4 20.8 12.8
10.6 15.7 15.0 -6.3*
1
-47.0
2
-0.7
3 4
0.3 -9.4
* 10 weeks after choline supplementation indicating return of hepatic steatosis.
HEPATOLOGYVol. 22, No. 5, 1995
BUCHMAN ET AL
marked increase in liver density. The CT number difference yielded by the liver-spleen subtraction method improved by an average 20 _+ 16.5 HU (-14.2 +_ 22.3 to 8.4 _+ 10.3 HU; P = .002). As in our previous study, changes in absolute liver CT numbers correlated well with changes in the the liver-spleen CT number difference (r = .98). Hepatic steatosis continued to decrease during the 6 weeks of choline chloride supplementation and completely resolved in all four subjects. On concurrent scans the liver and spleen densities assumed a normal, or near-normal relationship. Although plasmafree choline concentrations were similar to their baseline values 4 weeks after choline chloride was discontinued, hepatic steatosis had not yet returned on the postsupplementation CT scans. Because of missed appointments, patient no. 4 was examined 10 weeks after the 6 weeks of choline chloride supplemented TPN had been discontinued. Her hepatic steatosis had recurred by that time (Table 1). Liver density appeared identical to the baseline CT scan, and the liver-spleen CT number difference returned to a negative value, as it had been at baseline. Serum AST and ALT activities are shown in Figs. 1 and 2. They showed no significant change during the study except for subject no. 1, who also had the most striking hepatic steatosis at baseline and the greatest relative increase in hepatic CT attenuation steatosis during the study (Table 1; Fig. 3). At baseline, three of the four subjects had normal AST, and two had normal serum ALT activity (Figs. 1 and 2). No change in total serum cholesterol or plasma phospholipid-bound choline was observed during the study (Fig. 4). Plasma-free choline decreased in the normal volunteers after 1 week of choline-free TPN (Table 2).
DISCUSSION In our previous study, we found a significant negative correlation between liver-fat density and plasma-
I- ~- Subject --B--Subject1 2 80 70 60 50 ALT 40
~ ---)4
I
X - Subject --&-- Subject I 3 4 I
,.,
.×., ""X ....
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~,
....
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I
I
I
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I
I
1
2
3
4
5
6
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Week Fig. 1. Serum ALT activities before, during, and after choline chloride supplementation (normal, 5 to 50 U/L).
-e-
1401
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I
AST 40 ~,
u/I 30
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,
t
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1
2
3
4
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Week Fig. 2. Serum AST activities before, during, and after choline chloride supplementation (normal, 5 to 40 U/L).
free choline concentration, even when the plasma-free choline level remained below normal. 2 Our current study shows that hepatic steatosis associated with long-term TPN, is probably caused by choline deficiency in the absence of overfeeding or fatty acid deficiency and/or protein deficiency. The steatosis can be ameliorated with choline-supplemented TPN. We and others have shown that plasma-free choline concentration is low in nearly all patients who receive long-term TPN. 1'2'15'16 The prevalence of hepatic steatosis in patients who receive parenteral nutrition is difficult to ascertain. Our previous data 2 along with studies by Host et a117 and Grant et al is suggest this figure is approximately 50% to 60%. Shapiro et a115 also observed a decrease in hepatic steatosis in one patient, who required TPN because of severe protein calorie malnutrition after supplementation with orally administered choline, in addition to tyrosine, cyst(e)ine and carnitine. One patient had no steatosis before supplementation, but it developed subsequent to the initiation of TPN and the oral supplements. However, because their patients were extremely malnourished, it was unclear if the hepatic steatosis in the former patient was related to protein malnutrition and/or fatty acid deficiency. Resolution may have occurred after improvement in his overall nutritional status. No calorie, lipid, or protein intake information was provided for the second patient. It is possible that rapid overfeeding led to the development of hepatic steatosis independent of choline status. Plasma-free choline concentrations decreased within 1 week, even in well-nourished normal volunteers who were provided with TPN as an exclusive source of nutritional support (Table 2). Therefore, choline should probably be provided in the solutions of all patients receiving long-term TPN. Our current study confirms data from our previous study 2 that showed serum transaminase activities are
1402
BUCHMAN ET AL
HEPATOLOGYNovember 1995
I-
Subject - - B - 1
Subject2
- Subject 3
-- &-- Subject I I
4
I
240
Cholesterol
mg/dl
200,
"'--X"
160
~
120
. ~ -
. X , . ,,, .X, . " ~ ' - ' X ~" . "-,, ~ . , X . _. _ x=j "" - ""
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8o, 40
0
I
I
I
i
I
I
I
1
2
3
4
5
6
10
Week Fig. 4. Plasma lipid-bound choline concentrations before and after choline chloride supplementation.
Fig. 3. (A) Liver CT scan before choline chloride supplementation (patient no. 1) showing marked hepatic steatosis (-47.0). (B) Liver CT scan after 2 weeks of choline chloride supplementation (patient no. 1) showing hepatic steatosis (-3.9 HU). (C) Liver CT scan after 6 weeks of choline chloride supplementation (patient no. 1) showing no hepatic steatosis (3.3 HU).
both insensitive and nonspecific indicators of changes in the degree of hepatic steatosis. Many patients who require TPN may develop unrecognized hepatic steatosis, because they do not manifest serum hepatic transaminase elevations. In addition, as we have previously shown, 1 transaminase increases in patients that receive TPN are not necessarily caused by hepatic steatosis; drugs, chronic hepatitis, and other factors may also contribute. Lipid emulsions such as Intralipid (Clintec, Deerfield, IL) contain some choline, primarily in the form of phosphatidylcholine, but our pre~i~us study, 2 as well as work by Sheard et al, 16 have shown this amount to be small. They contain very little free choline. Choline should be synthesized from the methionine contained in TPN solutions. However, the intravenous delivery of nutrients bypasses the portal system, and the firstpass effect of dietary choline through the liver. Therefore, we speculate IV methionine is probably not metabolized to choline and the low but detectable plasma choline concentrations in our subjects probably reflect some, albeit minimal, dietary methionine and choline absorption. Shapiro et a115 have also suggested low plasma choline concentrations may be related to a defective hepatic transsulfuration pathway on the basis of low plasma choline, carnitine, cyst(e)ine, and tyrosine concentrations in their two patients who required TPN for severe protein calorie malnutrition. That is probably the explanation for the finding of increased normal to elevated plasma methionine concentrations in home TPN p . a t i ~ r ~ ' s f i ' 1 ~ ' ~ ...... Deficient phosphatidylcholine may result in an inability of the liver to transport triglyceride as part of lipoproteins. 21We cannot explain why hepatic steatosis occurs despite normal plasma phospholipid-bound choline concentration. A previous study, 2 as well as our current study, has shown the degree of hepatic steatosis is correlated only with plasma-free choline
HEPATOLOGYVol. 22, No. 5, 1995
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1403
TABLE 2. I n t r a v e n o u s C h o l i n e , L i p i d E m u l s i o n D o s a g e , a n d P l a s m a - F r e e C h o l i n e C o n c e n t r a t i o n i n C h o l i n e - D e f i c i e n t Patients and Normal Volunteers Receiving TPN
Patient No.
Choline Chloride (g/d)
Intralipid 20% (mL/d)
Plasma Free Choline (nmol/mL) Baseline
Week 1
Week 2
Week 3
Week 4
Week 5
Week 6
Week 10"
1 2 3 4 Normal volunteers (n = 8)
4 2 3 3 0
428 34 84 112 462 _+ 63
5.2 7.4 6.6 3.7 9.4 _+ 0.4
19.7 54.5 36.2 33.6 7.7 _+ 0.8
20.2 16.9 23.0 38.1 7.6 + 0.5
27.9 16.3 21.1 40.5 N/A
7.3 10.6 26.6 28.5 N/A
18.2 26.1 32.6 40.8 N/A
19.7 5.9* 21.1 27.6 N/A
3.8 8.9 N/A 6.6 N/A
Abbreviation: N/A, not available. * Choline discontinued.
concentration. It is possible that plasma phosphatidyl choline is not transported into hepatocytes or that a blockage exists in the metabolism of phosphatidylcholine to free choline. Choline elimination is a function of tissue uptake and metabolism as well as urinary excretion. 4 The choline dose should be adjusted in patients with impaired hepatic and/or renal function. 4 However, as indicated in our present study, a plateau is reached at which time plasma-free choline concentrations do not continue to increase, although they m a y vary from week to week (Table 2). We would recommend that the plasma choline level be monitored weekly or biweekly until a plateau level in the normal range is achieved. Choline levels should therefore be monitored, as should any other nutrient such as potassium, zinc, and so on, added to the TPN solution. In conclusion, choline m a y be an essential nutrient in patients with minimal oral intake or absorption. Choline deficiency results in hepatic steatosis that may be reversed by the addition of choline to TPN solutions. Because the addition of choline to TPN solutions ameliorates hepatic steatosis, it is likely that choline supplementation at initiation of TPN will prevent or blunt the development of hepatic steatosis. Our data are preliminary, but suggest the need for larger, randomized, controlled clinical trials of choline-supplemented TPN in the treatment and prevention of TPN-associated liver disease.
6. 7. 8. 9.
10.
11. 12.
13. 14. 15.
16. REFERENCES
1. Buchman AL, Moukarzel AA, Jenden DJ, Roch M, Rice K, Ament ME, et al. Hepatic transaminase abnormalities are associated with low plasma free choline in patients receiving long-term parenteral nutrition. Clin Nutr 1993;12:38-42. 2. Buchman AL, Dubin M, Jenden D, Moukarzel A, Roch MH, Rice K, Gornbein J, et al. Lecithin increases plasma free choline and decreases hepatic steatesis in long-term total parenteral nutrition patients. Gastroenterology 1992;102:1363-1370. 3. Buchman AL, Moukarzel AA, Eckhert C, Ament ME, Eckhert C, Bhuta S, Mestecky J, et al. The effects of TPN on intestinal morphology and function in man. Transplant Proc 1994; 26:1457. 4. Buchman AL, Jenden DJ, Moukarzel AA, Roch M, Rice KM, Chang AS, Ament ME. Choline pharmacokinetics during intermittent choline infusion in humans. Clin Pharmacol Ther 1994;55:277-283. 5. Jenden DJ, Roch M, Booth RA. Simultaneous measurement of
17. 18.
19. 20.
21.
endogenous and deuterium-labeledtracer variants of choline and acetylcholine in subpicomole quantities by gas chromatography spectrometry. Anal Biochem 1973;55:438-448. Freeman JJ, Choi RL, Jenden DJ. Plasma choline: its turnover and exchange with brain choline. J Neurochem 1975;24:729-734. Folch J, Lees M, Stanley GHS. A simple method for the isolation and purification of total lipids from animal tissue. J Bio Chem 1957;226:497-509. Jope RS, Jenden DJ. Choline and phospholipid metabolism and the synthesis of acetylcholine in rat brain. J Neurosci Res 1979;4:69-82. Ducommon J, Goldberg HI, Royal SA, Koroblein M, Moss AA, Kressel HY, et al. The relation of fatty liver to computed tomography numbers: a preliminary experimental study in rabbits. Radiology 1979;130:511-513. Peikarski J, Goldberg HI, Royal SA, Axel L, Moss AA. Differences between liver and spleen CT numbers in the normal adult: its usefulness in predicting the presence of diffuse liver disease. Radiology 1980;137:727-729. Bydder GM, Chapman RW, Harry D, et al. Computed tomography attenuation values in fatty liver. J Comp Tomo 1981;5:3335. Yajima Y, Naruri T, Motoyasu I, Abe R, Ohtsuki M, Goto Y, Endo S, et al. Computed tomography in the diagnosis of fatty liver: total lipid content and computed temography number. Tohoku J Exp Med 1982;136:337-342. Bashist B, Hecht HL, Harley WD. Computed tomographic demonstration of rapid changes in fatty infiltration of the liver. Radiology 1982;142:691-692. Goodacre RL, Hunter DJ, Millward S, Pirani M, Riddell RH. The diagnosis of acute fatty liver of pregnancy by computerized tomography. J Clin Gastroenterol 1988;10:680-682. Shapiro G, Chawla RK, Berry CJ, Williams PJ, Roy RGB, Rudmen D. Cysteine, tyrosine, choline and carnitine supplementation of patients on total parenteral nutrition. Nutr Int 1986;2:334-339. Sheard NF, Tayek JA, Bistrian BR, Blackburn GL, Zeisel SH. Plasma choline concentrations in humans fed parenterally. Am J Clin Nutr 1986;43:219-224. Host WR, Serlin O, Rush BF. Hyperalimentation in cirrhotic patients. Am J Surg 1972;123:57-56. Grant JP, Cox CE, Kleinman LM, Maher MM, Pittman MA, Tangrea JA, Brown JH, et al. Serum hepatic enzymes and bilirubin elevations during parenteral nutrition. Surg Gynecol Obstet 1977;145:573-580. Dahlstrom KA, Ament ME, Laidlaw SA, Kopple JD. Plasma amino acid concentrations in children receiving long-term parenteral nutrition. J Pediatr Gastroenterol Nutr 1988;7:748-754. Chawla RK, Berry CJ, Kutner MH, Rudman D. Plasma concentrations of transsulfuration pathway products during nasoenteral and intravenous hyperalimentation of malnourished patients. Am J Clin Nutr 1985;42:577-584. Zeisel SH. Vitamin-like molecules. In: Shils ME, Young VR, eds. Modern nutrition in health and disease. Ed 7th. Philadelphia: Lee and Farber, 1988:440-452.