Growth hormone levels in severe renal failure

Growth H o r m o n e Levels in Severe Renal Failure B y NAGUIB A. SAMAAN AND RICHARD M. FREEMAN

Fasting plasma growth hormone was 6 m~g./ml, or more in 13 of 21 patients with severe renal failure. Growth hormone levels of control subjects regularly decreased following an intravenous infusion of glucose. In contrast, the growth hormone levels of only three of 21 uremic patients were suppressed by glucose, eleven of the patients exhibiting a paradoxical rise. We observed no positive correlation between the degree of growth hormone elevation and the abnormality of glucose tolerance. Growth hormone

levels were also measured at four hourly intervals during hemodialysis. Increasing the glucose concentration of dialysate did not noticeably modify the growth hormone response to hemodialysis in these patients. The pathologic significance of increased growth hormone in uremia is unknown. The carbohydrate intolerance and hyperinsulinism associated with uremia must however be attributed to factors other than growth hormone alone. (Metabolism 19: No. 2, February, 102113, 1970)

N 1966 O N E O F US O B S E R V E D paradoxical rises in growth hormone following glucose infusion in six patients with advanced renal failure? Subsequently, high growth hormone levels in uremia have been observed by others. 2'3 These observations have raised a number of interesting questions. Do the high growth hormone levels contribute to the carbohydrate intolerance observed in patients with renal failure? Are growth hormone levels elevated in patients receiving maintenance hemodialysis? What changes occur in growth hormone during the actual dialysis procedure? Does variation in the glucose concentration in the dialysate produce any significant change in the growth hormone level observed? This paper is an attempt to answer these questions.

I

MATERIALS AND METHODS Thirty-three male adult subjects were studied. Group I patients included ten subjects who had received twice-weekly hemodialysis for an average of 18 months (range 6-39 months). The diagnosis in seven was chronic glomerulonephritis; other diagnoses were Goodpastnre's syndrome (J.B.), hereditary nephritis (A.W.), chronic pyelonephritis (R.W.). The mean creatinine clearance was less than 1 ml./min, and all patients were oliguric (Table 1). Each patient had been repeatedly instructed on diets with variable sodium restriction (400-1200 mg.), moderately decreased protein (1 Gm./Kg. body weight) and the avoidance of high-potassium-containing foods. Each patient came to the hospital twice weekly for a 12-hour hemodialysis on the modified Kiil Dialyzer. Glucose infusion was From the Department of Medicine, Veterans Administration Hospital and University of Iowa Hospitals, Iowa City, Iowa. Received for publication April 7, 1969. Supported by grants from Veterans Administration Hospital, USPH IROT HD: 354-01 and HD~04383-.01, and College of Medicine, University of Iowa Hospitals, Iowa City, Iowa ,(XO01). NAGUIBA. SAMAAN,M.D.: Chief, Section of Endocrinology, University of Texas, Houston, Texas. RICI-IARDM. FREEMAN, M.D.: Assistant Professor of Medicine and Director of Dialysis Facilities, University of Iowa College of Medicine, Iowa City, Iowa.

102

METABOLISM,VOL. 19, No. 2 (FEBRUARY), 1970

GROWTH HORMONE LEVELS

103

r O ~

t.., v~

tm-~

°~

eqeq

.~--:,,....~eq,--.~,--~,,-.~eq

r~

-~,,o e~

t',,It",l'~--~t"qt"q

t"q

*q.~.

,~,.A

o',, o o

¢5 ,--;

o6~

o~

104

SAMAAN AND FREEMAN

V

t~

5 _=

I

~

~

~

m

1 ~~

~~ ~

~

"2".

~

I~ ~

°

~

V

~

GROWTH HORMONE LEVELS

105

done on the morning of a regularly-scheduled dialysis, four days after the last hemodialysis. Group II was composed of eleven azotemic patients who were being evaluated as possible candidates for chronic hemodialysis (Table 2). On the day of the study the mean plasma urea nitrogen was 108 mg./100 ml and the mean plasma creatinine was 12.6 mg./100 ml. Only one of these 11 patients (R.K.) was oliguric. With the exception of patients G.F. and W. C., dietary protein was restricted to from 20 to 40 Gm. daily at the time of this study. Group III control subjects included twelve normal males, 25 to 52 years of age, with normal blood urea nitrogen and blood pressure. All were on unrestricted diets. None of the subjects was receiving thiazides at the time these studies were performed. Patients with evidence of active infection were excluded from the study. Eight of the 11 Group II patients were hospitalized at the time of the study. All other subjects were nonhospitalized and ambulatory. All arrived at the hospital in a fasting state at approximately 7 a.m. for studies and were rested for a period of from 30 to 60 minutes before the start of the glucose infusion. Twenty per cent hypertonic glucose (1 Gm./Kg. body weight) was infused intravenously over a one-hour period by means of an automatic pump. Blood samples from the opposite arm were obtained in the fasting state and at 30 minute intervals for the next two hours. In Groups II and III, heparinized blood samples were obtained through a scalp vein needle. Repeated venipunctures were avoided by clearing the needle and tubing with a dilute solution of heparin and saline and clamping the tubing with a hemostat between samplings. Blood samples from Group I patients were obtained directly from the arterial end of the arteriovenous cannula. In 12 determinations of simultaneously sampled arterial and venous blood, the arterial glucose was 4.3 % ( + 2.9% ) higher than the venous sample. In addition to the intravenous glucose infusion tests, ten patients were also studied during 12 continuous hours of hemodialysis on the Kill dialyzer. Blood samples were obtained before dialysis and at the fourth, eighth and twelfth hours of dialysis. The studies were performed with the glucose concentration of the dialysate at 201) mg./100 ml. and at 1600 mg./100 ml. The studies with the 200 mg./100 ml. glucose concentration were separated from the study with the 1600 mg./100 ml. concentration by two to six weeks. Patients were not fasted during this part of the study, and indeed, attempts were made to simulate routine dialysis conditions, except for the variation of the glucose concentration of the dialysate. Growth hormone was labeled by the method of Greenwood et al.4 and measured by the method of Schalch and Parker5 as modified by Samaan et al.6 Uremic plasma had no measurable influence on growth hormone as determined by recovery experiments (Table 4). Plasma insulin values were obtained by the double antibody technique of Morgan and Lazarow.7 Blood glucose was measured by the ferricyanide method, modified for Autoanalyzer use. Statistics were performed by standard methods, s RESULTS T h e m e a n fasting h u m a n growth h o r m o n e ( H G H ) level of the twelve G r o u p I I I control subjects was 2.9 ~ 0.5 m/zg./ml. ( T a b l e s 3 a n d 5 ) . T h e H G H level at the end of the glucose i n f u s i o n ( 6 0 m i n u t e s ) was 1.5 ± 0.3 m ~ g . / m l . , a level significantly lower t h a n the fasting value. T h e H G H was suppressed b y glucose i n f u s i o n in each of the n o r m a l subjects tested. T h e fasting H G H level of the G r o u p I I u r e m i c patients was 8.5 m # g . / m l . ( ± 2 . 5 ) a value significantly higher t h a n the controls ( T a b l e s 2 a n d 5 ) . I n contrast to the control subjects, after 60 m i n u t e s of glucose infusion the H G H level was paradoxically higher t h a n the fasting level in n i n e of the eleven patients tested. T h e fasting H G H level of the G r o u p I dialysis patients ( T a b l e s 1 a n d 5) was likewise elevated at 8.4 ± 1.0 m ~ g . / m l . Seven of the ten patients showed a

106

SAMAAN AND FREEMAN

o

,,.o d,

o

. . . .

V

~

~

~V

~

~

V

~

~

V

~V

~

~

~d ~ .

V

~

V

V

~

V

~

~o

o

~

~

V

~

d

~

~o

~D

107

GROWTH HORMONE LEVELS Table 4.--Recovery Studies in "Uremic" Plasma* J.B. B.S. W.S.

Before Adding HGH

After Adding 6 mbtg. HGIt

22 18 22

29 23 28

(60-minute sample) (fasting sample) (120-Minute sample)

*Measurement of plasma before and after addition of 6 m/,g. HGH to each sample.

paradoxical rise in growth hormone with higher levels after 60 minutes of glucose infusion than when fasting. Glucose excess (defined as the difference between the two-hour blood glucose and the fasting blood glucose) was used to measure carbohydrate intolerance to minimize the influence of non-glucose reducing substances that are also measured when using the ferricyanide method. In Fig. 1, the fasting growth hormone levels of Group I and Group II patients are plotted against glucose excess; no positive correlation was noted (r = -0.54). The plasma albumin of twelve dialysis patients are listed in Table 6 along with fasting and 60 minute growth hormone levels. The plasma albumin ranged from 2.9 to 4.0 Gin./100 ml. As can be seen, there is no inverse correlation between the plasma albumin and growth hormone level in this group of subjects. Observations noted during the actual hemodialysis appear in Table 7 and Fig. 2. As anticipated, when the dialysate glucose was 1600 mg./100 ml., the blood glucose levels were higher in most of the patients than when the dialysate contained 200 rag./100 ml. glucose. The rise in circulating insulin with a 1600 mg./100 ml. glucose concentration was even more striking. Suppression of the blood growth hormone levels, however, was no more noticeable when the patients were dialyzed against 1600 mg./100 ml. glucose than when dialyzed against 200 rag./100 ml. glucose. DISCUSSION

It is clear from our data that high growth hormone levels are frequent in patients with severe renal failure. Of perhaps more importance was the lack of

X(31) ® = GROUP I I

®

E

x = GROUP'Ir

15

X

O n.O T -r I.--

®

10

X ®

O nr f,,.9 Z

®®

Fig. 1.--Fasting growth hormone versus glucose excess in patients with renal failure.

®

®

®

®

5

t,-0") ,.¢ LL

X

x

x

®x X i

- 50

0

i

+50

+100

GLUCOSE

EXCESS

¥

+150

108

SAMAAN AND FREEMAN

~

VVV

~ ~

zz~

~ ~ s

zz~

~

~

VVV

~

~

VVV

5 ra

,r..r.

g I=

r~

z~

~i ~

8

i=

=

o

,.4

~o =

:::1.

= Izl o

5 ~

f,.q

+t

+]

+f

°

I¢i o.

V V

°~

~g ,4---

109

GROWTH HORMONE LEVELS Table 6 . - - S e r u m A l b u m i n and Growth Levels in 12 Patients Receiving Maintenance l t e m o d i a l y s i s Patient

Serum Albumin Gm./100 ml.

E.B. J.S. A.R. T.K. W.N. D.L. R.W. D.N. G.Q. LP. A.W. LB.

2.9 3.0 3.1 3.1 3,1 3.3 3,5 3,5 3.7 3.7 3.9 4.0

Growth H o r m o n e (m/~g./ml.) Fasting 60-minute

4.7 11 5.8 6 6.6 7 8.8 16 13.8 9 7 8.2

5.3 21 6.4 11 5 6.7 8.8 8.8 16 9.8 9.6 22

growth hormone suppression following glucose infusion. Only one of the ten dialysis patients (D.N.) had a growth hormone level at the end of the glucose infusion which was clearly less than that observed at fasting; growth hormone suppression following glucose infusion was noted in only two of the eleven nondialysis uremic patients (G.Q. and T.T.). Observations of a similar nature have been made by others. In the study by -

"(,13 '

300

200rag % 1600rag %

-

. . . .

O~

2oo 0

~

::~

9m-

~

T-

I

I00

I

z

3O

"r e

20

o

IO

0

{

. . . . .

I

I

I

Fig. 2.--Changes in blood glucose, growth hormone and insulin during hemodialysis; response to different dialysate glucose.

(.0 I

I

/J:

200

Z~

I

I

.... -I- .... -I

/

4O I

I

I

0

4

8

HOUR OF DIALYSIS

I

12

110

SAMAAN AND FREEMAN T a b l e 7 . - - N o n f a s t i n g G r o w t h H o r m o n e , G l u c o s e a n d I n s u l i n Levels i n B l o o d During "Routine" Hemodialysis

Patient

1600 rag./100 ml. 4

8

12

9.6 16 23.5 30.4 19 17 18 9.4 4.5 21.5

5.0 6.6 13.0 25.0 17 12 15 12 4.6 21

5.2 6.5 15.7 19.0 21.5 15 12.5 8.4 5.5 21.8

5.3 6.2 16.0 17,0 30.1 11.2 13.6 9.8 9.8 24

9 21 25.5 50 33 2.2 28 6.2 29 11.7

5.3 38 19 30 16 3.8 24 5.8 32 5.7

4.4 23 20 41 30 4.2 23 6,6 36 6.9

4.5 37 22 28 44 4.1 22 6.7 28 9

Mean SEN

16.9 2.4

13.1 2.1

13.1 2.0

14.3 2.5

21.6 4.6

18.0 4.0

19.5 4.3

20.5 4.5

Pa~ent

0

4

Glucose (mg./100ml.) 8 12

0

4

8

12

150 123 88 70 106 118 159 120 124 128

124 153 130 132 122 126 149 128 130 188

119 114 128 158 111 104 163 128 112 171

138 104 159 84 125 92 148 124 118 165

138 130 79 102 145 118 84 159 100 157

238 150 133 332 163 171 173 217 114 208

186 166 143 524 137 147 140 164 174 223

212 143 137 484 137 166 116 177 308 168

Mean SE~

119 8

138 6

131 8

126 9

121 9

190 20

200 37

205 35

Patient

0

4

8

0

4

8

12

52 19 16 28 12 52 20 17 28

42 38 48 50 27 32 <4 16 112

26 24 52 108 15 38 <4 17 156

36 15 132 <4 32 35 < 4 18 100

100 30 23 23 48 18 40 12 55

336 88 250 104 100 132 48 120 200

240 88 280 176 38 58 38 52 160

248 79 136 180 38 44 40 232 140

27 5

41 10

49 17

42 15

39 9

153 31

126 31

126 27

J.B.

D.L. D.N. J.P. J.S. A.W. R.W. E.B. G.Q. W.N.

I.B. D.L. D.N. J.P. J.S. A.W. R.W. E.B. G.Q. W.N.

LB. D.L. D.N. I.P. J.S. R.W. E.B. G.Q. W.N. Mean SE~

0

Dialysate Glucose 200 rag./100 ml. Growth Hormone (m/~g./ml.) 4 8 12

Insulin /~U./ml.) 12

0

Horton, Johnson, and Lebovitz, 2 nine of sixteen azotemic patients had fasting plasma growth hormone levels which were two standard deviations above the normal mean. They studied the growth hormone response to 25 Gm. of glucose given intravenously over a 1-2-minute period. When the growth hormone re-

GROWTH HORMONE LEVELS

111

sponses of individual uremic patients were compared with those of normal individuals, ten of the uremics could not be distinguished from normal, whereas six clearly had growth hormone levels above normal. A more heterogenous population of patients with renal failure was studied by Wright et al. ~ The fasting serum growth hormone was elevated in approximately half of their patients. Twenty-four of the 41 subjects showed either no suppression of growth hormone or a paradoxical rise in the hormone level during an oral glucose tolerance test. In their study the only direct measurement of chronic renal failure that correlated with mean serum growth hormone was the serum creatinine. An inverse correlation between serum albumin and growth hormone however was emphasized. It was suggested that the high growth hormone levels are a reflection of protein malnutrition, a consequence of renal failure. The carbohydrate intolerance associated with the uremic state has been attributed to insulin antagonism. 9,1° Since growth hormone acts as an insulin antagonist under certain circumstances, the role of growth hormone in the production of the carbohydrate intolerance of uremia was evaluated. The fasting growth hormone levels of our patients are plotted against glucose excess (the difference between the two hour blood sugar and the fasting blood sugar) in Fig. 1. There was no positive correlation between fasting growth hormone levels and glucose excess observed in these patients. The carbohydrate intolerance and the hyperinsulinism associated with uremia must be attributed to factors other than high growth hormone alone. Interpretation of data on glucose and insulin is complicated by three factors. (1) Urinary losses of glucose during the two hours of the present study were not determined. Since significant urinary losses of glucose in the hemodialyzed patients are unlikely because of severe oliguria, the dialysis patients may have received a relatively larger glucose load than the control subjects. This may be partly responsible for the higher plasma glucose and insulin values observed in dialysis subjects. This difference should however tend to minimize rather than to accentuate the abnormalities in growth hormone, i.e., the greater glucose load in the uremic patient should suppress the growth hormone more than usual. (2) The ferricyanide method we used to determine glucose measures nonglucose substances such as creatinine and uric acid. 11,~2 The contribution of nonglucose reducing substances should not however vary significantly within the two hours of the glucose infusion. Therefore, glucose excess (the difference between the two hour blood sugar and the fasting blood sugar) was used as a quantitative measure of glucose intolerance. (3) Blood glucose is slightly higher in the dialysis patients since blood was taken from the arterial cannula in contradistinction to Group II and III subjects where venous blood was utilized. We have found the arterial samples to be approximately 4 per cent higher than the simultaneously obtained venous blood samples; no correction has been made in the data for this difference, however. Magnesium as an insulin antagonist was considered because of a report that magnesium depletion in dogs leads to increased removal of intravenously administered glucose from the blood stream? z If magnesium deficiency stimulates glucose removal, could magnesium excess, a common occurrence in renal in-

112

SAMAAN AND FREEMAN

sufficiency, inhibit peripheral glucose uptake? No correlation was noted between plasma magnesium and glucose excess in our patients (r = 0.20). The lack of correlation as well as observations of glucose intolerance in two other uremic patients with hypomagnesemia makes magnesium excess an unlikely factor in the genesis of carbohydrate intolerance of uremia. The pathogenesis of the growth hormone abnormality in uremia is not clear to us. We do not have the data to confirm the suggestion of Wright et al. 3 that protein malnutrition is the underlying cause. Stress as a stimulus to growth hormone release has been well documented.14,15 Acute stress, at least, seems an unlikely explanation. The dialysis patient had been coming to the hospital twice weekly for an average of 18 months; many procedures more stressful than this simple intravenous infusion had been experienced. Indeed, the procedure was probably more stressful to our control subjects than to patients if familiarity with procedures and hospital environment has any bearing on stress response. The importance of amino acid metabolism in the pathogenesis of high growth hormone levels in our patients is also unknown. Increased growth hormone levels in response to the infusion of arglnine and other amino acids has been shown. 16 Although the amino acid pattern of uremic plasma is certainly not normal, ~7 we have no data on the relationship of amino acids to growth hormone in this particular group of patients. ACKNOWLEDGMENTS The authors wish to acknowledge the technical assistance of Sandra L. Anderson, Marjorie Eckrich, Carl W. Wathen, and Judith Crone.

REFERENCES 1. Samaan, N., Cumming, J. S., Craig, 1. W., and Pearson, O. H.: Serum growth hormone and insulin levels in severe renal disease. Diabetes 15:546, 1966. 2. Horton, E. S., Johnson, G., and Lebovitz, H. E.: Carbohydrate metabolism in uremia. Ann. Intern. Med. 68:63, 1968. 3. Wright, A. D., Lowy, C., Fraser, T. R., Spitz, I. M., Rubenstein, A. H., and Bersohn, I.: Serum growth hormone and glucose intolerance in renal failure. Lancet 2:798, 1968. 4. Greenwood, F. C., Hunter, W. M., and Klopper, A.: Assay of human growth hormone in pregnancy at parturition and in lactation. Detection of a growth-hormonelike substance from the placenta. Brit. Med. J. 1:22, 1964. 5. Schalch, D. S., and Parker, M. L.: A sensitive double antibody immuno-assay for human growth hormone in plasma. Nature (London) 203:1141, 1964. 6. Samaan, N., Yen, S. C. C., Friesen, H., and Pearson, O. H.: Serum placental lactogen levels during pregnancy and in trophoblastic disease. J. Clin. Endocr. 26:

1303, 1966. 7. Morgan, C. R., and Lazarow, A.: Immunoassay of insulin: Two antibody system plasma insulin levels of normal, subdiabetic and diabetic rats. Diabetes 12:115, 1963. 8. Snedecor, G. W., and W. G. Cochran: Statistical Methods (ed. 6). Ames, Iowa, Iowa State University Press, 1967. 9. Hampers, C. L., Soeldner, J. S., Doak, P. B., and Merrill, J. P.: Effect of chronic renal failure and hemodialysis on carbohydrate metabolism. J. Clin. Invest. 45:1719, 1966. 10. Perkoff, G. T., Thomas, C. L., Newton, J. D., Sellman, J. C., and Tyler, F. H.: Mechanism of impaired glucose tolerance in uremia and experimental hyperazotemia. Diabetes 7: 375, 1958. 11. Westervelt, F. B., Jr., and Schreiner, G. E.: The carbohydrate intolerance of uremic patients. Ann. Int. Med. 57:266, 1962. 12. Teuscher, A.: Beuteilung der Blutzuckerwerte und der Glukose-toleranz bei Uremie (Evaluation of blood sugar and glu-

GROWTH HORMONE LEVELS cose tolerance in uremia). Schweiz. Med. Wschr. 94:69, 1964. 13. Kahil, M. E., Parrish, J. E., Simons, M. A., and Brown, H.: Magnesium deficiency and carbohydrate metabolism. Diabetes 15:734, 1966. 14. Meyer, V., and Knobil, E.: Growth hormone secretion in the unanesthetized Rhesus monkey in response to noxious stimuli. Endocrinology 80:163, 1967. I5. Muller, E., Saito, T., Arimura, A., and Schally, A. V.: Hypoglycemia, stress and growth hormone release: Blockade of growth hormone release by drugs acting on

113 the central nervous system. Endocrinology 80:109, I967. 16. Knopf, R. F., Conn, I. W., Fajans, S. S., Floyd, J. C., Jr., Gtmtache, E. M., and Rull, J. A.: Plasma growth hormone response to intravenous administration of amino acids. J. Clin. Endocr. 25:1140, 1965. 17. Gulyassy, P. F., Peters, J. H., Lin, S. C., and Ryan, P. M.: Hemodialysis and plasma amino acid composition in chronic renal failure. Amer. J. Clin. Nutr. 21:565, 1968u