Muscle-Protein Catabolism after Injury in Man, as Measured by Urinary Excretion of 3-Methylhistidine

Abstract

1. Urinary excretion of 3-methylhistidine, an index of the rate of muscle breakdown, has been measured during the first 7 days in patients after elective surgery or accidental injury. 2. There was no major difference between the mean daily excretion after skin grafting or total hip replacement, or in injured patients who were hyperketonaemic for the first 24 h after admission. 3. The group of injured patients who did not develop hyperketonaemia had a mean urinary 3-methylhistidine excretion which was twice that of the other groups. 4. It is concluded that increased breakdown of muscle protein makes a major contribution to the greater urinary nitrogen excretion in the normoketonaemic group of injured patients.

Effect of beta-hydroxybutyrate on whole-body leucine kinetics and fractional mixed skeletal muscle protein synthesis in humans.

“…This hypothesis is supported by the demonstration of decreased glucose production rate in humans (5) and in pigs (6), and a decrease in urinary excretion of nitrogen in fasted human subjects during intravenous infusion off,-hydroxybutyrate (j#-OHB)' (7). Improvement of nitrogen retention in postoperative patients in proportion to their hyperketonemia (8) lends additional support to the hypothesis. 1.…”

Free amino acid excretion in tetraplegic patients

“…It has been shown that patients with traumatic injury and no increase in blood ketones have twice more urine 3-methylhistidine than those with hyperketonemia because they have an excessive muscle protein breakdown (Williamson, 1977). However, Hoover-Plow (1978) found that in rats, after surgery without ketosis, the breakdown occurs in muscle sarcoplasma, where the protein metabolism, mostly catabolism, is augmented, and in myofibrils, where the protein anabolism is depressed.…”

Biology-based nutritional support of critically ill and injured patients

“…Severely critically ill and injured patients characteristically demonstrate significant muscle losses and negative nitrogen balance [4][5][6][7][8][9][10][11][12][13][14][15]. The metabolic response to injury is associated with a striking increase in protein catabolism, along with a marked increase in urinary loss of nitrogen, phosphorus, sulfur, potassium, magnesium, and creatinine.…”