Histidines and renal function.

The results of endogenous renal clearances of 3-methylhistidine and histidine in twelve patients with normal and decreased renal functions are reported. Differences in the renal handling of the amino acids have been established. 3-methylhistidine showed a hyperbolic relationship between serum concentration and inulin clearance: histidine a linear relationship. The percentage tubular reabsorption of 3-methylhistidine was found to be about half that of histidine. The possible use of the measurement of serum 3-methylhistidine concentration as an index of renal insufficiency is discussed.