The occurrence of lactyl lactate and succinyl lactate in the urine of patients screened for inherited metabolic disease

The gas Chromatographic and mass spectrometric identification of lactyl lactate and succinyl lactate, both present in human urine, is described. In the gas chromatogram lactyl lactate (as TMS derivative) presented as two peaks: the l,L- and/or d,d-form as well as the d, l- and/or the l,d-enantiomer. Both l- and d-lactyl succinate were excreted simultaneously. Lactyl lactate was observed in many patients; succinyl lactate only a few times and only together with lactyl lactate. No correlation with (endogenous) urinary lactate could be established. Presumably these compounds are products of the intestinal bacteria.