Urinary lactate excretion in normal children and in children with enzyme defects of carbohydrate metabolism.

Urinary lactate was analyzed in 53 normal children, 7 children with glucose-6-phosphatase-deficient glycogenosis, 1 child with fructose-1,6-diphosphatase deficiency and 1 child with pyruvate dehydrogenase deficiency. Lactate in 24-h urine was expressed as concentration, total excretion, excretion per kg body weight and per 1.73 m2 body surface, and as lactate/creatinine quotient. Of these parameters, the lactate concentration in 24-h urine showed the smallest variation in normal children (0.155 +/- 0.053 mM), whereas in patients with one of the above mentioned enzymopathies 10-300-fold elevations were found. The lactate/creatinine quotient, normal range 0.010 to 0.058 (mM/mM) was also used to correct for unnoticed losses of urine. Both parameters, used in conjunction with blood lactate analysis, are suitable for a first screening of patients with enzymopathies of carbohydrate metabolism, and for the follow-up study of the steady or unsteady state of the patient with an enzyme defect of carbohydrate metabolism.