Free amino acid excretion in tetraplegic patients.
Free amino acid chromatographic fingerprints obtained in automated analysers in 24-hour urines may help to quantitate muscle and collagen changes occurring after cerival spinal cord injury. The technique was used to compare the urine of six healthy and ten tetraplegic men, 18 to 25 years old, three of whom became paralysed in diving, one in a mountain fall, one one in the fall of a pipe, four in car accidents, and one in a football game. Nine weeks to 14 years after injury, the tetraplegics excreted less total free amino acids, lysine, and 3-methylhistidine than the controls, whereas hydroxyproline and hydroxylysine were similar in both groups. Values of urine 3-methylhistidine, measured 9, 13, 19 and 20 weeks post onset in one patient, and 9, 12, 16, 18, 23, and 26 weeks post onset in another, were related to the duration of paralysis. These results indicate that collagen and muscle metabolism may not be quantitated by measuring urine free amino acids.