A model of L(+)-lactate metabolism in normal man.

Mathematical models were used to study the elimination of L(+)-lactate during and after an intravenous load of unlabelled sodium L(+)-lactate in 20 normal postprandial subjects. Clearance of L(+)-lactate from blood was 17.9 +/- 1.1 ml (kg BW)-1 min-1 and the endogenous production rate of L(+)-lactate at rest was 1.38 +/- 0.16 mol (70 kg BW)-1 24 h-1. Clearance and production were unchanged after a 36-hour fast in 4 subjects. Renal excretion of L(+)-lactate accounted for less than 1.2% of the infused load. Clearance of L(+)-lactate was closely related to the pre-infusion concentrations of ketone bodies and alanine.