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Myoglobinuria in Chronic Renal Failure
Myoglobinuria in Chronic Renal Failure Donald A. Feinfeld, MD, Anne M. Briscoe, PhD, Hazeline M. Nurse, MD, Jeanne L. Hotchkiss, MD, and Gerald E. Thomson, MD • Serum and urine myoglobin levels were determined on 14 patients with stable chronic renal failure. Serum myoglobin ranged from 38 to 350 ng/mL. Eleven patients had myoglobinuria between 15 and 250 ng/mL; none developed myoglobinuric renal failure. Fractional excretion of myoglobin in the myoglobinuric patients increased as creatinine clearance decreased, although there was no correlation between filtered load and excretion rate of myoglobin. This confirms that renal failure leads to hypermyoglobinemia and usually to myoglobinuria. Surviving nephrons tend to reabsorb less of the filtered load of myoglobin as renal function diminishes. © 1986 by the National Kidney Foundation, Inc. INDEX WORDS: Myoglobin; chronic renal failure; clearance.
M
YOGLOBIN, the major oxygen-carrying protein of striated muscle, is normally found in the blood in low concentrations. l Although myoglobinuria has long been known to be a cause of acute renal failure, it has only recently been recognized that renal failure causes high serum myoglobin. 2 We previously reported that azotemia of varying etiology is associated with myoglobinuria as well as hypermyoglobinemia and that this myoglobinuria does not lead to acute renal failure as it does in the case of massive muscle injury. 3 The purpose of the present study was to examine more closely the relationship between urinary excretion of myoglobin and glomerular filtration in patients with stable chronic renal failure. MATERIALS AND METHODS
Studies were done on specimens from 14 patients at Harlem Hospital Center with stable chronic renal failure or insufficiency, observed by the Renal Service in the clinic or in consultation for periods ranging from 2 weeks to 2 months with no change in serum creatinine during that time. None had any clinical or biochemical evidence of muscle disease or injury. Myoglobin levels were determined in surplus serum and urine (from these patients) sent to the Biochemistry Laboratory for determination of creatinine and 24-hour urinary protein levels, and the results were correlated with the creatinine clearance and urine protein excretion. Myoglobin was determined by radioimmunoassay using a method developed by Stone et al' (Nuclear Medical Systems, Inc, Newport Beach, Calif). All determinations were done in duplicate and verified by myoglobin reference controls at high and low levels. Our laboratory results have found a mean serum myoglobin of 33 ± 4 ng/mL in normal subjects.' Creatinine was measured by the Jaffe reaction on a Technicon AutoAnalyzer (Technicon Instruments Corp, Tarrytown, NY). Urine protein was measured using a turbidometric method.' Clearances of creatinine and myoglobin were determined by the standard formula C, = U, x VIP" where U, and P, are the urine and serum concentrations, respectively, of the solute
!, and V the urine volume per unit time. Fractional excretion of myoglobin was calculated by dividing the amount of myoglobin excreted in the urine per unit time (Umyo x V) by the amount of myoglobin filtered per unit time (Pmyo X Cc. x glomerular sieving coefficient of myoglobin [0.75]), S with the result expressed as a percent. Linear regression was performed using the method of least squares.
RESULTS
Patients' serum creatinine levels ranged from 1.5 to 12.4 mg/dL (mean 4.5 ± 2.7 mg/dL) and creatinine clearances from 6.5 to 47.3 mLlmin. As can be seen in Table 1, the patients had serum myoglobin levels ranging from 38 to 350 ng/mL. Eleven individuals had detectable urinary myoglobin, ranging from 15 to 250 ng/mL. There was a weak correlation between serum and urine myoglobin concentrations (r = .48, P < .05). Patients with the lowest creatinine clearances tended to have higher levels of urine myoglobin. There was a modest inverse correlation between urinary myoglobin concentration and creatinine clearance (r = - .59, P < .025). In these patients, the amount of urinary myoglobin per mg of urinary protein was a very small fraction and did not appear to have a consistent relationship to the degree of either proteinuria or myoglobinuria (Table 1). Myoglobin clearance was undetectable in three patients and ranged from 0.4 to 5.3 mLlmin in those with myoglobinuria. The highest clearance From the Department of Medicine, Harlem Hospital Center, Columbia University College of Physicians and Surgeons, New York. Address reprint requests to Donald A. Feinfeld, MD, Chief, Renal Division, Department of Medicine, Harlem Hospital Center, 506 Lenox Ave, New York, NY 10037. © 1986 by the National Kidney Foundation, 1nc. 0272-6386/86/0802-0006$03.00/0
American Journal of Kidney Diseases, Vol VIII, No 2 (August), 1986: pp 111-114
111
112
FEINFELD ET AL Table 1.
Urine and Serum Myglobin in Patients with Renal Dysfunction
Patient No.
(mUmin)
Serum Myo (ng/mL)
Urine Myo
Uprot
(ng/mL)
(mg/d)
1 2 3 4 5 6 7 8 9 10 11 12 13 14
47.3 40.8 38.6 33.4 31.6 30.3 21.0 19.8 18.0 17.7 12.7 10.2 7.9 6.5
40 190 175 96 50 70 38 190 200 68 44 215 66 350
15 94 0 20 30 0 180 130 0 26 42 140 150 250
742 767 265 267 77 749 1,000 370 732 75 192 360 392 4,900
Ce,
UmyolU prol IPg/mg)
Cmyo (mUmin)
0.030 0.125 0 0.208 0.584 0 0.288 0.759 0 9.617 0.188 0.595 0.528 2.483
0.4 0.4 0 0.4 0.6 0 5.3 1.0 0 0.5 0.6 0.7 2.2 0.7
Abbreviations: Myo, myoglobin; Up",!> urinary protein; Umyo , urinary myoglobin; Cmyo ' myoglobin clearance.
values occurred in the two patients in whom urine myoglobin concentration was higher than that in serum. Table 2 shows the amounts of myoglobin filtered and excreted by each patient per minute. There was no correlation between these two parameters. Fractional excretion of myoglobin (Table 2), in those patients with myoglobinuria, ranged from 1.07 to 36.76%, with the higher values tending to occur in those individuals with poorer renal function. There was a strong inverse correlation between the logarithm of the fractional excretion of myoglobin in the 11 myoglobinuric patients and the creatinine clearance (r = - .82, P < .005) (Fig 1). Table 2.
Filtered v Excreted Myoglobin
Patient No.
Myo Filtered (ng/min)
Myo Excreted (ng/min)
FEmyo
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1,419 5,814 5,066 2,405 1,185 1,591 599 2,822 2,700 903 419 1,645 391 1,706
15 66 0 39 31 0 200 195 0 32 25 149 144 253
1.07 1.15 0 1.61 2.64 0 33.42 6.91 0 3.56 5.99 9.04 36.76 14.86
(%)
Abbreviations: Myo, myoglobin; FE myo , fractional excretion of myoglobin.
100
•
I '&
I
1,·0
• y _29.3 e- OJI7x r --0.82 p
• •
• •
CNatlne CIMrance (mUmln)
Fig 1. Correlation of logarithm of fractional excretion of myoglobin and creatinine clearance in the 11 patients with myoglobinuria secondary to chronic renal failure.
MYOGLOBINURIA IN CHRONIC RENAL FAILURE
None of these patients developed acute worsening of renal function, and there was no evidence of the myoglobinuria causing acute renal failure. Although the urine of the patients with myoglobinuria ~ 150 ng/mL gave a positive orthotoluidine dipstick test (hematest), none of the urines had pigmented casts. DISCUSSION
Hallgren et al first noted a direct correlation between the levels of serum myoglobin and serum creatinine. 2 We have shown that serum myoglobin tends to increase as creatinine clearance decreases and that the high level of myoglobin in the blood usually leads to the appearance of myoglobinuria. 3 In contrast, normal individuals have either no urinary myoglobin or have levels below 5 ng/mL, the limit of detectability of this protein by radioimmunoassay.3,6 The concentration of myoglobin in the urine appeared to be related to the serum myoglobin, to some extent. However, there was a great deal of variation, ie, three patients with elevated serum myoglobin levels had no detectable myoglobinuria and two individuals had higher levels of myoglobin in their urine than in the serum. This is probably due in part to differences in the absorption of both myoglobin and water by the renal tubular cells. In addition, myoglobin in plasma is partly bound to a large nonhaptoglobin protein that might interfere somewhat with its passage through the glomerular filter.7 Kagen and Butt noted a certain amount of individual variation in this binding, 8 which might also affect urinary myoglobin concentrations. An early study of the renal handling of myoglobin did find a relationship between the urinary excretion of myoglobin and the amount filtered. 5 However, that was an experiment on the dog in which very large amounts of myoglobin were infused intravenously, greatly exceeding the maximal tubular transport (T m) for this protein. The Tm for myoglobin has been estimated to be approximately 3 mg/min.9 The highest myoglobin filtration rate in the present study was 5,814 ng/min, approximately three orders of magnitude lower. Hence, despite the marked reduction in renal function in these patients, it is likely (assuming animal data are valid in humans and the sieving coefficient for myoglobin remains constant for varying
113
degrees of renal function) that the threshold of myoglobin reabsorption was not exceeded and that tubular reabsorption of myoglobin affected the urinary myoglobin excretion. Hypermyoglobinemia does not invariably lead to myoglobinuria, even when there has been significant muscle necrosis.lo The decreased glomerular filtration rate in our patients did appear to have some effect on the renal handling of myoglobin. An inverse relationship was found between creatinine clearance and fractional excretion of myoglobin in those 11 patients who had detectable urinary myoglobin, with a strong semilogarithmic correlation. This suggests that despite the variation in urinary myoglobin excretion, the residual functioning nephrons tend to reabsorb less of the filtered load of myoglobin as their number decreases. Despite the presence of detectable urinary myoglobin in 11 of the patients studied, all maintained a steady glomerular filtration rate over 2 to 8 weeks. This confirms our earlier contention that myoglobinuria does not always inexorably lead to acute renal failure. 3 The finding of urinary myoglobin in a patient with azotemia does not per se mean that the patient has myoglobinuric renal failure. It is likely that there has to be a certain high level of myoglobin in the urine before tubular injury takes place, as well as some degree of renal hypoperfusion. The diagnosis of myoglobinuric renal failure should be made on clinical grounds, such as the presence of muscle crush or heat injury or markedly elevated serum creatinine kinase. 6 ACKNOWLEDGMENT The authors would like to thank Phyllis Gomez for technical assistance and Helen Mortimer for assistance in completing the manuscript.
REFERENCES 1. Stone MJ, Willerson JT, Gomez-Sanchez CE, et al: Radioimmunoassay of myoglobin in human serum. J Clin Invest 56:1334-1339,1975 2. Hiillgren R, Karlsson FA, Roxin LE, et al: Myoglobin turnover-influence of renal and extrarenal factors. J Lab Clin Med 91:246-254, 1978 3. Hart PM, Feinfeld DA, Briscoe AM, et al: The effect of renal failure and hemodialysis on urine and serum myoglobin. Clin NephroI18:141-143, 1982 4. Henry RJ, Sobel C, Segalove M: Turbidometric determination of proteins with sulfosalicylic and trichloracetic acids. Proc Soc Exp Bioi Med 92:748-751, 1956
114 5. Yuile CL, Clark WF: Myohemoglobinuria: A study of the renal clearance of myohemoglobin in the dog. J Exp Med 74:187-196, 1941 6. Rowland LP: Myoglobinuria, 1984. Can J Neurol Sci 11:1-13,1984 7. Wheby MS, Barrett 0 Jr, Crosby WH: Serum protein binding of myoglobin, hemoglobin and hematin. Blood 16:1579-1585, 1960
FEINFELD ET AL
8. Kagen U, Butt A: Myoglobin binding in human serum. Clin Chern 23:1813-1818, 1977 9. Maack T, Johnson V. Kau ST, et al: Renal filtration, transport, and metabolism of low-molecular weight proteins. Kidney Int 16:251-270, 1979 10. Koffler A, Friedler RM, Massry SG: Acute renal failure due to nontraumatic rhabdomyolysis. Ann Intern Med 85:2328, 1976
M
YOGLOBIN, the major oxygen-carrying protein of striated muscle, is normally found in the blood in low concentrations. l Although myoglobinuria has long been known to be a cause of acute renal failure, it has only recently been recognized that renal failure causes high serum myoglobin. 2 We previously reported that azotemia of varying etiology is associated with myoglobinuria as well as hypermyoglobinemia and that this myoglobinuria does not lead to acute renal failure as it does in the case of massive muscle injury. 3 The purpose of the present study was to examine more closely the relationship between urinary excretion of myoglobin and glomerular filtration in patients with stable chronic renal failure. MATERIALS AND METHODS
Studies were done on specimens from 14 patients at Harlem Hospital Center with stable chronic renal failure or insufficiency, observed by the Renal Service in the clinic or in consultation for periods ranging from 2 weeks to 2 months with no change in serum creatinine during that time. None had any clinical or biochemical evidence of muscle disease or injury. Myoglobin levels were determined in surplus serum and urine (from these patients) sent to the Biochemistry Laboratory for determination of creatinine and 24-hour urinary protein levels, and the results were correlated with the creatinine clearance and urine protein excretion. Myoglobin was determined by radioimmunoassay using a method developed by Stone et al' (Nuclear Medical Systems, Inc, Newport Beach, Calif). All determinations were done in duplicate and verified by myoglobin reference controls at high and low levels. Our laboratory results have found a mean serum myoglobin of 33 ± 4 ng/mL in normal subjects.' Creatinine was measured by the Jaffe reaction on a Technicon AutoAnalyzer (Technicon Instruments Corp, Tarrytown, NY). Urine protein was measured using a turbidometric method.' Clearances of creatinine and myoglobin were determined by the standard formula C, = U, x VIP" where U, and P, are the urine and serum concentrations, respectively, of the solute
!, and V the urine volume per unit time. Fractional excretion of myoglobin was calculated by dividing the amount of myoglobin excreted in the urine per unit time (Umyo x V) by the amount of myoglobin filtered per unit time (Pmyo X Cc. x glomerular sieving coefficient of myoglobin [0.75]), S with the result expressed as a percent. Linear regression was performed using the method of least squares.
RESULTS
Patients' serum creatinine levels ranged from 1.5 to 12.4 mg/dL (mean 4.5 ± 2.7 mg/dL) and creatinine clearances from 6.5 to 47.3 mLlmin. As can be seen in Table 1, the patients had serum myoglobin levels ranging from 38 to 350 ng/mL. Eleven individuals had detectable urinary myoglobin, ranging from 15 to 250 ng/mL. There was a weak correlation between serum and urine myoglobin concentrations (r = .48, P < .05). Patients with the lowest creatinine clearances tended to have higher levels of urine myoglobin. There was a modest inverse correlation between urinary myoglobin concentration and creatinine clearance (r = - .59, P < .025). In these patients, the amount of urinary myoglobin per mg of urinary protein was a very small fraction and did not appear to have a consistent relationship to the degree of either proteinuria or myoglobinuria (Table 1). Myoglobin clearance was undetectable in three patients and ranged from 0.4 to 5.3 mLlmin in those with myoglobinuria. The highest clearance From the Department of Medicine, Harlem Hospital Center, Columbia University College of Physicians and Surgeons, New York. Address reprint requests to Donald A. Feinfeld, MD, Chief, Renal Division, Department of Medicine, Harlem Hospital Center, 506 Lenox Ave, New York, NY 10037. © 1986 by the National Kidney Foundation, 1nc. 0272-6386/86/0802-0006$03.00/0
American Journal of Kidney Diseases, Vol VIII, No 2 (August), 1986: pp 111-114
111
112
FEINFELD ET AL Table 1.
Urine and Serum Myglobin in Patients with Renal Dysfunction
Patient No.
(mUmin)
Serum Myo (ng/mL)
Urine Myo
Uprot
(ng/mL)
(mg/d)
1 2 3 4 5 6 7 8 9 10 11 12 13 14
47.3 40.8 38.6 33.4 31.6 30.3 21.0 19.8 18.0 17.7 12.7 10.2 7.9 6.5
40 190 175 96 50 70 38 190 200 68 44 215 66 350
15 94 0 20 30 0 180 130 0 26 42 140 150 250
742 767 265 267 77 749 1,000 370 732 75 192 360 392 4,900
Ce,
UmyolU prol IPg/mg)
Cmyo (mUmin)
0.030 0.125 0 0.208 0.584 0 0.288 0.759 0 9.617 0.188 0.595 0.528 2.483
0.4 0.4 0 0.4 0.6 0 5.3 1.0 0 0.5 0.6 0.7 2.2 0.7
Abbreviations: Myo, myoglobin; Up",!> urinary protein; Umyo , urinary myoglobin; Cmyo ' myoglobin clearance.
values occurred in the two patients in whom urine myoglobin concentration was higher than that in serum. Table 2 shows the amounts of myoglobin filtered and excreted by each patient per minute. There was no correlation between these two parameters. Fractional excretion of myoglobin (Table 2), in those patients with myoglobinuria, ranged from 1.07 to 36.76%, with the higher values tending to occur in those individuals with poorer renal function. There was a strong inverse correlation between the logarithm of the fractional excretion of myoglobin in the 11 myoglobinuric patients and the creatinine clearance (r = - .82, P < .005) (Fig 1). Table 2.
Filtered v Excreted Myoglobin
Patient No.
Myo Filtered (ng/min)
Myo Excreted (ng/min)
FEmyo
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1,419 5,814 5,066 2,405 1,185 1,591 599 2,822 2,700 903 419 1,645 391 1,706
15 66 0 39 31 0 200 195 0 32 25 149 144 253
1.07 1.15 0 1.61 2.64 0 33.42 6.91 0 3.56 5.99 9.04 36.76 14.86
(%)
Abbreviations: Myo, myoglobin; FE myo , fractional excretion of myoglobin.
100
•
I '&
I
1,·0
• y _29.3 e- OJI7x r --0.82 p
• •
• •
CNatlne CIMrance (mUmln)
Fig 1. Correlation of logarithm of fractional excretion of myoglobin and creatinine clearance in the 11 patients with myoglobinuria secondary to chronic renal failure.
MYOGLOBINURIA IN CHRONIC RENAL FAILURE
None of these patients developed acute worsening of renal function, and there was no evidence of the myoglobinuria causing acute renal failure. Although the urine of the patients with myoglobinuria ~ 150 ng/mL gave a positive orthotoluidine dipstick test (hematest), none of the urines had pigmented casts. DISCUSSION
Hallgren et al first noted a direct correlation between the levels of serum myoglobin and serum creatinine. 2 We have shown that serum myoglobin tends to increase as creatinine clearance decreases and that the high level of myoglobin in the blood usually leads to the appearance of myoglobinuria. 3 In contrast, normal individuals have either no urinary myoglobin or have levels below 5 ng/mL, the limit of detectability of this protein by radioimmunoassay.3,6 The concentration of myoglobin in the urine appeared to be related to the serum myoglobin, to some extent. However, there was a great deal of variation, ie, three patients with elevated serum myoglobin levels had no detectable myoglobinuria and two individuals had higher levels of myoglobin in their urine than in the serum. This is probably due in part to differences in the absorption of both myoglobin and water by the renal tubular cells. In addition, myoglobin in plasma is partly bound to a large nonhaptoglobin protein that might interfere somewhat with its passage through the glomerular filter.7 Kagen and Butt noted a certain amount of individual variation in this binding, 8 which might also affect urinary myoglobin concentrations. An early study of the renal handling of myoglobin did find a relationship between the urinary excretion of myoglobin and the amount filtered. 5 However, that was an experiment on the dog in which very large amounts of myoglobin were infused intravenously, greatly exceeding the maximal tubular transport (T m) for this protein. The Tm for myoglobin has been estimated to be approximately 3 mg/min.9 The highest myoglobin filtration rate in the present study was 5,814 ng/min, approximately three orders of magnitude lower. Hence, despite the marked reduction in renal function in these patients, it is likely (assuming animal data are valid in humans and the sieving coefficient for myoglobin remains constant for varying
113
degrees of renal function) that the threshold of myoglobin reabsorption was not exceeded and that tubular reabsorption of myoglobin affected the urinary myoglobin excretion. Hypermyoglobinemia does not invariably lead to myoglobinuria, even when there has been significant muscle necrosis.lo The decreased glomerular filtration rate in our patients did appear to have some effect on the renal handling of myoglobin. An inverse relationship was found between creatinine clearance and fractional excretion of myoglobin in those 11 patients who had detectable urinary myoglobin, with a strong semilogarithmic correlation. This suggests that despite the variation in urinary myoglobin excretion, the residual functioning nephrons tend to reabsorb less of the filtered load of myoglobin as their number decreases. Despite the presence of detectable urinary myoglobin in 11 of the patients studied, all maintained a steady glomerular filtration rate over 2 to 8 weeks. This confirms our earlier contention that myoglobinuria does not always inexorably lead to acute renal failure. 3 The finding of urinary myoglobin in a patient with azotemia does not per se mean that the patient has myoglobinuric renal failure. It is likely that there has to be a certain high level of myoglobin in the urine before tubular injury takes place, as well as some degree of renal hypoperfusion. The diagnosis of myoglobinuric renal failure should be made on clinical grounds, such as the presence of muscle crush or heat injury or markedly elevated serum creatinine kinase. 6 ACKNOWLEDGMENT The authors would like to thank Phyllis Gomez for technical assistance and Helen Mortimer for assistance in completing the manuscript.
REFERENCES 1. Stone MJ, Willerson JT, Gomez-Sanchez CE, et al: Radioimmunoassay of myoglobin in human serum. J Clin Invest 56:1334-1339,1975 2. Hiillgren R, Karlsson FA, Roxin LE, et al: Myoglobin turnover-influence of renal and extrarenal factors. J Lab Clin Med 91:246-254, 1978 3. Hart PM, Feinfeld DA, Briscoe AM, et al: The effect of renal failure and hemodialysis on urine and serum myoglobin. Clin NephroI18:141-143, 1982 4. Henry RJ, Sobel C, Segalove M: Turbidometric determination of proteins with sulfosalicylic and trichloracetic acids. Proc Soc Exp Bioi Med 92:748-751, 1956
114 5. Yuile CL, Clark WF: Myohemoglobinuria: A study of the renal clearance of myohemoglobin in the dog. J Exp Med 74:187-196, 1941 6. Rowland LP: Myoglobinuria, 1984. Can J Neurol Sci 11:1-13,1984 7. Wheby MS, Barrett 0 Jr, Crosby WH: Serum protein binding of myoglobin, hemoglobin and hematin. Blood 16:1579-1585, 1960
FEINFELD ET AL
8. Kagen U, Butt A: Myoglobin binding in human serum. Clin Chern 23:1813-1818, 1977 9. Maack T, Johnson V. Kau ST, et al: Renal filtration, transport, and metabolism of low-molecular weight proteins. Kidney Int 16:251-270, 1979 10. Koffler A, Friedler RM, Massry SG: Acute renal failure due to nontraumatic rhabdomyolysis. Ann Intern Med 85:2328, 1976