Urinary 3-methylhistidine:creatinine ratio in patients on long-term parenteral nutrition.

The urinary 3-methylhistidine (3-MH) and creatine excretion were measured serially in two patients on total parenteral nutrition for 201 and 225 days, respectively. Variations in excretion were related to clinical events, such as sepsis; 3-MH excretion and the 3-MH:creatinine ratio were raised in association with some episodes of infection, but not all. It is concluded that, although infection is often associated with increased myofibrillar protein breakdown, this is not always the case. It is suggested that in susceptible patients a high 3-MH:creatine ratio may indicate occult infection not detectable by other means.