The purpose of this study was to investigate the usefulness of urinary
lactate measurements to assess the adequacy of dietary treatment in patients with type I
glycogen storage disease (GSD-I). We determined the correlation of urine and blood
lactate concentrations in 21 GSD-I patients during 24-h admissions to the General Clinical Research Center (GCRC) during which hourly blood samples and aliquots of every void were obtained. In all but 1 patient, we found a good correlation between blood
lactate concentrations and urinary
lactate excretion. One patient did not excrete
lactate in significant amounts despite elevated blood
lactate concentrations. In 17 patients, the highest blood
lactate concentrations occurred during the night. Markedly elevated nighttime average blood
lactate concentrations above 3.5 mmol/l resulted in a urinary
lactate concentration above the normal limit of 0.067 mmol/mmol
creatinine in the first morning urine specimen. Mildly elevated nighttime blood
lactate concentrations (between 2.2 and 3.5 mmol/l) led to urinary
lactate concentrations that were either normal or moderately elevated. All patients with normal blood
lactate concentrations during the night also had normal first morning urinary
lactate concentrations. The degree of urinary
lactate excretion in relation to blood
lactate concentrations varied by individual. Urinary filter paper specimens, collected at home during the night and in the morning and mailed to the laboratory, were used to monitor the dietary compliance of 5 GSD-I patients at home over a period of 6 to 9 weeks prior to their GCRC admissions. These data suggested variable degrees of dietary control. In conclusion, the urinary
lactate concentration is a useful parameter to monitor
therapy of GSD-I patients at home. To be interpretable, the baseline urinary
lactate concentration in relation to the blood
lactate concentration has to be determined.