Muscle protein breakdown in premature human infants

Muscle protein breakdown in premature human infants can be quantified from the urinary excretion ratio of 3-methylhistidine (3MH) to creatinine. Only single urine samples are needed and no prior treatment of the infant is required. Use of this procedure over the past 10 years has established that rates of muscle protein breakdown increase rapidly in response to stress, infection or inadequate nutrition and return to normal once successful treatment has been achieved. Higher rates are also observed in very early premature infants. No effects of sex, time of day or the route of nutrient intake, whether parenteral or enteral, are observed. A marked fall in 3MH excretion occurs following indomethacin treatment, consistent with responses to prostaglandin inhibitors established previously in isolated muscle.