Battle Casualties in Korea, Studies of the Surgical Research Team, Volume I
Muscle Metabolism and Catabolism and Endogenous Creatinine
Clearances in Combat Casualties
First Lieutenant John P. Frawley, MSC, USAR
Lieutenant Colonel Curtis P. Artz, MC, USA
Captain John M. Howard, MC, USAR
with the technical assistance of
Corporal William B. Evans, AMEDS
It is generally accepted that creatinine produced by endogenous metabolism is derived from muscle creatine and phosphocreatine. The conversion is apparently the result of an irreversible process of normal metabolism which takes place at a constant rate, proportional to muscle mass and independent of muscular exercise.1, 2
The daily urinary excretion of creatinine is constant for the individual, ranging from 1.5 to 2.0 gm. for men and from 0.8 to 1.5 gm. for women. This corresponds to approximately 2 per cent of the total body creatine, from which it is derived. This excretion rate is apparently independent of protein ingestion and is considered an index of muscle metabolism. It is not influenced by exercise or urine volume. Decreased creatinine excretion, with concurrent elevation in plasma level, is generally indicative of impaired renal function since creatinine is freely filterable at the glomerulus. Decreased excretion in the absence of elevated plasma concentration is usually due to conditions associated with muscular atrophy and paralysis. Increased excretion is associated with increased endogenous muscle metabolism, resulting in the conversion of additional creatine to creatinine.1,2
Creatine is normally absent in the urine of adult men. The total body creatine is approximately 120 gm. with 98 per cent present in muscle tissue. Creatine does not normally appear in the plasma since its elimination is through creatinine, the waste product of creatine metabolism in muscle. The appearance of creatine in the urine of males is generally associated with wasting diseases, fevers and certain muscular dystrophies, and thus is an index of catabolism of muscle tissue.
Purpose
This study was undertaken to evaluate the response of muscle tissue to direct and indirect injury as part of the total body`s systemic response to injury.
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Specifically, the study may be subdivided as follows:
1. The metabolism of muscle tissue-as evidenced by the conversion of creatine to creatinine, following severe wounds with massive muscle damage and with minimal muscle damage.
2. The catabolism of muscle tissue-as evidenced by release of creatine following similar injuries.
Concurrent with these studies endogenous creatinine clearance measurements were made to evaluate the glomerular filtration rate of all patients and thereby take into account any effect from renal impairment.
Methods
Twenty-seven seriously wounded United Nations combat casualties were studied. Heparinized blood samples were drawn from all patients immediately following the operation and at 12- or 24-hour intervals thereafter. Urine specimens were collected for the same periods by indwelling catheters. All samples of plasma and urine were stored in the frozen state until analyzed.
The determination of creatinine was performed by a modification of the standard method of Bonsnes and Taussky3 which measures creatinine-like chromogens. In general the procedure was as follows:
A protein-free filtrate of plasma made from 3.0 ml. of plasma by adding 21 ml. of water, 3 ml. of 10 per cent sodium tungstate and 3.0 ml. of 0.66N sulfuric acid. The mixture was filtered after standing for 20 minutes. Duplicate 5.0 ml. aliquots of the filtrate were transferred to colorimeter tubes and 2.5 ml. of a fresh alkaline picrate solution (25 ml. 1 per cent picric acid to 5 ml. 10 per cent NaOH) was added, with shaking. The color which developed was read 20 minutes after the picrate addition at 510 millimicrons in a spectrophotometer. Urine samples were diluted 1 to 250 and aliquots of 2.5 ml. and 5.0 ml. were analyzed by similar technic. A blank standard and a curve were prepared during each series of determinations, with concentrations of 0, 5, 10, 20 and 40 micrograms. Any specimen furnishing an optimal density outside the range of standards was repeated with a more appropriate dilution.
The creatinine clearances were calculated by dividing the creatinine excretion per minute (ml./min. urine flow x mg./ml. creatinine in urine)by the mean plasma concentration during the period of urine collection.
There is no satisfactory method for the direct determination of creatine. However, the conversion of creatine to creatinine, by acid, although lacking specificity to a certain degree, is generally used for
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creatine measurement. Basically, the procedure used was that of Bonsnes and Taussky,3 which employs the conversion of creatine to creatinine by acid at 20 lbs. pressure and measurement of total creatinine before and after hydrolysis. Creatinine was measured by reaction with alkaline picrate and spectrophotometric measurement of the chromogen. The exact procedure for the conversion of creatine to creatinine was as follows: 5 ml. of 1/10 tungstate filtrate of plasma or 5 ml. of 1/250 dilution of urine were placed in covered tubes with 1 ml. NHCI and autoclaved for 20 minutes at 20 lbs. pressure per square inch. Four ml. of water was added and mixed. Five ml. and 2.5 ml. aliquots were analyzed for total creatinine with 2.5 ml. of alkaline picrate. The chromogen was read at 510 millimicrons and compared against a standard curve (0 to 40 micrograms). Equal aliquots of unhydrolyzed samples were measured for preformed creatinine and subtracted from the total. The increase in creatinine content after hydrolysis was converted to creatine by multiplying by 1.16.
The interference of dextran or gelatin with the measurement of creatinine or creatine by the alkaline picrate method was ruled out. Concentrations as high as 3 per cent dextran and 1.5 per cent gelatin did not significantly affect the determination of either creatinine or creatine. Occasionally a cloudiness would develop in the sample but centrifugation eliminated any spectrophotometric interference.
An empirical classification of casualties was made in relation to degree of muscle damage. Patients who had severe muscle damage were those with major extremity amputation or requiring extensive surgical removal of muscle tissue. Those with minimal muscle damage include less evulsive, penetrating wounds of the extremity. Abdominal perforations were present in both categories.
Results
1. Metabolism of Muscle Tissue
In order to evaluate the response of muscle tissue to trauma in casualties with direct, extensive muscle damage and with minimal muscle damage, the excretion of creatinine in the urine of 27 combat casualties was studied. Since the conversion of creatine to creatinine is believed to be primarily a function of muscle, the excretion rate of creatinine, in the absence of renal impairment, should be an index of muscle metabolism.
Tables 1 and 2 show the 24-hour urinary excretion levels of creatinine for the 27 patients studied. Table 3 shows the average endogenous creatinine clearances for the same patients for the same period. It was noted that every patient showed an increased excretion at one
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interval or another during the study (7.9 gm. per day in one patient), but never below normal (1.5 to 2.0 gm. per day) unless accompanied by renal impairment. Moreover, this increased excretion appeared to be independent of the severity of muscle injury. For example, patients 7, 9 and 10 who sustained penetrating wounds of the abdomen without other involvement demonstrated increased creatinine excretion as high as 4.9 gm. per day, whereas patients15 and 20 who sustained amputations of two extremities showed only minimal increases in creatinine excretion, 2.6 gm. per day.
Thus it appears that muscle metabolism of creatine to creatinine is increased in all seriously wounded patients, and does not appear to be a function of degree of muscle damage.
Table 1. 24-Hour Creatinine Excretion (g.m.) in Casualties with Severe Muscle Damage
| Postoperative Days | ||||||
1 | 2 | 3 | 4 | 5 | 6 | 7 | |
3 | *2.9 | 3.0 | 2.6 | --- | --- | --- | --- |
4 | 4.0 | 3.5 | 2.5 | 1.7 | 1.9 | 2.3 | 2.1 |
6 | 5.7 | 6.2 | 2.9 | --- | --- | --- | --- |
11 | *1.0 | *1.2 | --- | --- | --- | --- | --- |
12 | 1.9 | 2.7 | 2.9 | 2.9 | 2.6 | 2.7 | 2.6 |
13 | 3.8 | 3.5 | 2.3 | 3.2 | --- | *1.5 | --- |
15 | *2.2 | 2.6 | 2.3 | --- | --- | --- | --- |
16 | 4.2 | --- | --- | --- | --- | --- | --- |
17 | 2.4 | *2.3 | 2.6 | --- | --- | --- | --- |
18 | 3.4 | 2.9 | 2.8 | --- | --- | --- | --- |
19 | 2.1 | 2.2 | 2.5 | --- | --- | --- | --- |
20 | 1.9 | 1.9 | 2.2 | 2.1 | 1.9 | 1.9 | 2.0 |
21 | 4.7 | 3.1 | 2.6 | 4.5 | 4.7 | 3.1 | 2.8 |
23 | 1.5 | 1.9 | 1.8 | 2.0 | 2.2 | 2.4 | --- |
26 | --- | --- | 2.6 | 2.8 | 2.5 | 2.4 | --- |
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*Endogenous creatinine clearance below 75 ml. per minute.
2. Catabolism of Muscle Tissue
To evaluate the degree of muscle catabolism as might be effected by direct or indirect muscle trauma, urinary creatine excretion rates were studied in 14 of the previously reported casualties. Seven of these had sustained extensive muscle damage and the other seven
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minimal damage. Since creatine does not normally appear in the plasma and urine, excretion was considered an indication of muscle destruction.
Table 2. 24-Hour Creatinine Excretion (g.m.) in Casualties with Minimal Muscle Damage
| Postoperative Days | ||||||
1 | 2 | 3 | 4 | 5 | 6 | 7 | |
1 | 3.5 | 3.1 | 3.9 | 3.6 | 2.9 | 2.9 | 3.0 |
2 | 3.0 | 2.9 | 2.6 | --- | --- | --- | --- |
5 | 3.8 | *3.1 | *2.5 | *1.0 | *2.9 | *2.1 | --- |
7 | --- | 3.5 | --- | --- | --- | --- | --- |
8 | 7.9 | 4.0 | --- | --- | --- | --- | --- |
9 | 4.9 | *3.0 | *2.0 | *2.1 | *1.3 | *1.5 | *2.0 |
10 | *0.7 | 2.8 | 1.8 | --- | --- | --- | --- |
14 | 5.1 | 3.3 | 2.9 | 3.2 | --- | --- | --- |
22 | 2.5 | 3.6 | 3.7 | 3.5 | --- | --- | --- |
24 | *1.1 | *1.6 | --- | --- | --- | --- | --- |
25 | 3.0 | --- | --- | --- | --- | --- | --- |
27 | 2.5 | 1.9 | 1.9 | 2.1 | 2.5 | --- | --- |
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*Endogenous creatinine clearance below 75 ml. per minute.
Tables 4 and 5 show the 24 excretion rates for the patients studied. It was noted that all patients with extensive muscle damage excreted creatine at abnormal rates, as high as 3.9 gm. per day. The patients with minimal muscle damage showed some creatinurea, but significantly less in degree.
3. Endogenous Creatinine Clearance
Endogenous creatinine clearance studies were performed at all intervals of urine collection. Samples of urine and plasma were collected at either 12- or 24-hour intervals. Table 3 gives the average clearance values for each 24-hour period. It will be noted that the majority of the patients studied showed adequate clearance rates. Normal clearances have been reported to range from 80 to 108 when corrected to standard body surface.4 However, a greater spread in normal values results when surface area is not measured, as in the patients herein reported.
Of the 27 patients studied, only 4 patients (5, 9, 11 and 24) demonstrated any persistent degree of glomerular impairment. Patients
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5, 9 and 11 sustained abdominal wounds and patient 24 sustained a shoulder wound involving the brachial artery. Nevertheless, these patients improved subsequently and did not require artificial kidney dialysis. Two additional patients (10 and 15) showed decreased creatinine clearance on the first postoperative day but improved markedly thereafter.
Table 3. Endogenous Creatinine Clearances for 27 Combat Casualties
| Postoperative Days | ||||||
1 | 2 | 3 | 4 | 5 | 6 | 7 | |
1 | 103 | 107 | 139 | 136 | 113 | 108 | 108 |
2 | 107 | 124 | 121 | --- | --- | --- | --- |
3 | 74 | 86 | 85 | --- | --- | --- | --- |
4 | 135 | 138 | 102 | 77 | 97 | 116 | 107 |
5 | 79 | 57 | 33 | 12 | 29 | 20 | --- |
6 | 196 | 200 | 100 | --- | --- | --- | --- |
7 | --- | 107 | --- | --- | --- | --- | --- |
8 | 285 | 140 | --- | --- | --- | --- | --- |
9 | 188 | 70 | 49 | 52 | 35 | 38 | 53 |
10 | 33 | 125 | 82 | --- | --- | --- | --- |
11 | 40 | 58 | --- | --- | --- | --- | --- |
12 | 71 | 109 | 116 | 120 | 116 | 124 | 121 |
13 | 139 | 128 | 80 | 106 | --- | 55 | --- |
14 | 207 | 127 | 112 | 126 | --- | --- | --- |
15 | 56 | 80 | 81 | --- | --- | --- | --- |
16 | 111 | --- | --- | --- | --- | --- | --- |
17 | 77 | 71 | 105 | --- | --- | --- | --- |
18 | 140 | 117 | 128 | --- | --- | --- | --- |
19 | 90 | 84 | 140 | --- | --- | --- | --- |
20 | 82 | 111 | 140 | 121 | 99 | 98 | 109 |
21 | 190 | 113 | 95 | 169 | 178 | 124 | 91 |
22 | 80 | 128 | 135 | 130 | --- | --- | --- |
23 | --- | 94 | 86 | 98 | 92 | 101 | --- |
24 | 45 | 65 | --- | --- | --- | --- | --- |
25 | 88 | --- | --- | --- | --- | --- | --- |
26 | --- | --- | 108 | 121 | 135 | --- | --- |
27 | 99 | 90 | 146 | 120 | 97 | --- | --- |
Several of the patients (6, 8, 9, 14 and 21) studied showed clearance levels in excess of 150. The abnormally high clearance rate of these patients is reflected by their total creatinine excretion, Tables 1 and 2. This elevated clearance rate may be due to increased tubular excretion, which is an accepted phenomenon.
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Table 4. 24-Hour Creatine Excretion (gm.) in Casualties with Severe Muscle Damage
| Postoperative Days | ||||||
1 | 2 | 3 | 4 | 5 | 6 | 7 | |
3 | 0.1 | 0.5 | 0.8 | --- | --- | --- | --- |
4 | 0.4 | 1.8 | 1.9 | 0.3 | 0.7 | 1.2 | 1.1 |
15 | 2.0 | 3.4 | 3.3 | --- | --- | --- | --- |
17 | 1.9 | 3.8 | 3.9 | --- | --- | --- | --- |
19 | 0.3 | 0.7 | 0.7 | --- | --- | --- | --- |
20 | 0.1 | 0.4 | 1.0 | 1.6 | 2.6 | 2.7 | 2.2 |
23 | 0.7 | 0.8 | 0.9 | 1.1 | 1.2 | 1.2 | --- |
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Table 5. 24-Hour Creatine Excretion (gm.) in Combat Casualties with Minimal Muscle Damage
| Postoperative Day | ||||||
1 | 2 | 3 | 4 | 5 | 6 | 7 | |
1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.5 | 0.5 |
5 | 0.2 | 0.4 | 1.0 | 0.6 | 1.6 | 1.0 | --- |
7 | --- | 0.1 | 0.1 | --- | --- | --- | --- |
8 | 0.1 | 0.1 | --- | --- | --- | --- | --- |
9 | 1.0 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
14 | 0.1 | 0.3 | 0.6 | 0.1 | --- | --- | --- |
22 | 0.2 | 0.7 | 1.1 | 0.7 | --- | --- | --- |
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Table 6 shows the plasma creatinine levels of these patients and provides an additional indication of the kidney efficiency in clearing the plasma of excess creatinine. It was noted that the majority of the patients possessed a high plasma creatinine level. A rapid fall in plasma concentration, however, was observed in all patients except patient number 5.
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Table 6. Plasma Creatinine Levels (gm. per100 cc.)- 27 Combat Casualties
| Postoperative Days | |||||||
0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | |
1 | 2.4 | 2.4 | 1.9 | 2.0 | 1.9 | 1.7 | 2.0 | 1.9 |
2 | 2.6 | 1.8 | 1.6 | 1.5 | 1.4 | --- | --- | --- |
3 | 2.8 | 2.7 | 2.5 | 2.0 | 1.9 | --- | --- | --- |
4 | 2.7 | 2.0 | 1.8 | 1.6 | 1.8 | 1.3 | 1.4 | 1.4 |
5 | 3.0 | 3.4 | 4.4 | 6.2 | 7.0 | 7.0 | 7.4 | --- |
6 | 1.8 | 2.0 | 2.1 | 2.1 | 1.7 | --- | --- | --- |
7 | --- | 3.1 | 3.6 | 2.6 | 2.3 | --- | --- | --- |
8 | 2.5 | 1.9 | 2.0 | --- | --- | --- | --- | --- |
9 | 2.5 | 1.9 | 2.2 | 2.0 | 1.9 | 1.9 | 1.9 | 1.9 |
10 | 1.4 | 1.6 | 1.1 | 1.6 | 1.9 | --- | --- | --- |
11 | 1.8 | 1.6 | 1.4 | --- | --- | --- | --- | --- |
12 | 1.6 | 1.9 | 1.8 | 1.8 | 1.6 | 1.6 | 1.4 | 1.6 |
13 | 1.9 | 1.9 | 1.9 | 2.2 | 2.0 | 1.9 | 1.9 | --- |
14 | 1.7 | 1.8 | 1.8 | 1.8 | 1.7 | --- | --- | --- |
15 | 3.3 | 2.3 | 5.2 | 1.7 | --- | --- | --- | --- |
16 | 2.7 | 2.8 | 1.9 | --- | --- | --- | --- | --- |
17 | 3.0 | 2.0 | 2.0 | 2.1 | 1.7 | --- | --- | --- |
18 | 2.0 | 2.2 | 1.8 | 1.5 | 1.3 | --- | --- | --- |
19 | 1.9 | 1.4 | 1.4 | 1.2 | 1.2 | --- | --- | --- |
20 | 1.6 | 1.6 | 1.7 | 1.4 | 1.4 | 1.4 | 1.3 | 1.3 |
21 | 1.8 | 1.6 | 2.0 | 2.0 | 1.8 | 1.8 | 1.8 | 1.6 |
22 | 2.5 | 2.0 | 2.0 | 1.8 | 2.0 | 1.8 | --- | --- |
23 | --- | 1.8 | 1.9 | 1.8 | 1.6 | 1.8 | 1.6 | --- |
24 | 2.1 | 1.8 | 1.6 | 1.7 | --- | --- | --- | --- |
25 | 3.0 | 2.1 | --- | --- | --- | --- | --- | --- |
26 | 1.9 | 1.6 | 1.4 | 2.2 | 1.2 | 1.3 | 1.2 | --- |
27 | 1.9 | 1.5 | 1.6 | 1.3 | 1.4 | 1.2 | --- | --- |
Discussion
As the figures in Tables 1 and 2 indicate, increased creatinine excretion occurs with all types of wound. It is impossible to state that such excretion would occur without any muscle damage since all patients possessed some degree of muscle damage. It is also difficult and not infallible to establish a classification of degree of muscle damage. Because of the empirical nature of the classification, several patients found in one category might more logically belong in the other. However, regardless of the classification, increased creatinine excretion appears to be a normal response to injury, and since the formation
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of creatinine is almost exclusively a function of muscle metabolism an increase in muscle metabolism appears to follow injury.
The catabolism of muscle tissue, as measured by the excretion of creatine, however, appears to be a function of the degree of muscle damage. It must be noted that the classification according to muscle damage may include other factors contributing to the observed difference in creatine excretion. Perhaps concurrent with extensive muscle damage is an increased residual traumatized tissue which must be reabsorbed and excreted before the healing process can progress. Nevertheless, postoperative muscle catabolism in these patients was significantly greater in the presence of extensive muscle damage.
It should be noted that the loss of creatine, as represented by the combined creatine and creatinine excretion, is in the neighborhood of 25 per cent of the total body creatine in the first 7 postoperative days (patients1, 4, and 21). The question, whether this profound loss is compensated by increased body synthesis or is an actual depletion in a vital constituent of carbohydrate metabolism, must await further investigation.
Conclusion
An increase in muscle metabolism, as measured by urinary creatinine excretion, was observed in 27 combat casualties. The increase appeared to be independent of type, degree, or location of the injury.
An increase in muscle catabolism, as measured by urinary creatine excretion, was observed in patients sustaining extensive muscle damage. The increase was significantly less in patients with minimal muscle damage.
Endogenous creatinine clearance in these patients revealed a frequent impaired glomerular function on the first postoperative day, but only occasionally thereafter. Frequent increased creatinine clearances were observed, suggestive of increased tubular excretion.
In general, a systemic response to serious injury, independent of wound site, was observed by an increased metabolism of muscle tissue. A local response in the form of muscle catabolism following extensive muscle injury was also observed.
References
1. Beard, H. H.: The Biochemistry of Creatine and Creatinine. Ann. Rev. Biochem. 10: 246, 1941.
2. Benedict. S. R., and Osterberg, E.: J. Biol. Chem.56: 229, 1923.
3. Bonsnes, R. W., and Taussky, H. H.: J. Biol. Chem.158: 581, 1945.
4. Camera, A. A. et al.: J. Lab. Clin. Med. 37:743, 1951.
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Appendix
Wound Description
Patient 1. Penetrating wounds of right leg, groin, abdomen, chest and left arm.
Patient 2. Penetrating wounds of scrotum, both legs, hand and face.
Patient 3. Penetrating wounds of abdomen (involving liver and right kidney), right arm, both legs and buttocks.
Patient 4. Penetrating wounds of abdomen, both arms, both legs, pelvis and buttocks.
Patient 5. Penetrating wounds of abdomen, spinal cord and thigh.
Patient 6. Penetrating wounds of the abdomen, buttocks and left thigh.
Patient 7. Penetrating wound of the abdomen (involving stomach, spleen, kidney and pancreas).
Patient 8. Penetrating wounds of abdomen, right hand and arm, and right flank.
Patient 9. Penetrating wound of abdomen.
Patient 10. Penetrating wound of abdomen (involving spleen).
Patient 11. Penetrating wounds of abdomen, left leg (amputation),back, left shoulder, right hand and right leg (compound fracture).
Patient 12. Penetrating wounds of both legs.
Patient 13. Penetrating wounds of right foot, ankle, thigh and left foot (amputation).
Patient 14. Penetrating wounds of right hip and chest.
Patient 15. Penetrating wounds of scrotum, left thigh, right leg (amputation) and right forearm (amputation).
Patient 16. Penetrating wounds of left leg (massive) and right ankle (amputation).
Patient 17. Penetrating wounds of left mandible, left arm (fracture),left thigh, left knee and right forearm.
Patient 18. Penetrating wounds of left femur (massive).
Patient 19. Penetrating wounds of right foot (amputation), both legs, right hand.
Patient 20. Penetrating wounds of both legs (amputation) and right buttocks.
Patient 21. Penetrating wounds of right foot (amputation) and right leg.
Patient 22. Penetrating wounds of both legs and left arm (brachial artery).
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Patient 23. Penetrating wounds of right foot and ankle (amputation),right thigh, right hand (fracture).
Patient 24. Penetrating wounds of shoulder and arm (brachial artery).
Patient 25. Penetrating wounds of both legs, left arm and shoulder.
Patient 26. Penetrating wounds of right leg (amputation), left leg.
Patient 27. Penetrating wounds of right leg (compound fracture),left leg, left hip and left hand.
