Short-term exogenous galactose supplementation does not influence rate of appearance of galactose in patients with classical galactosemia

Introduction. Recently, evidence has been presented that adult patients with classical galactosemia have higher than expected galactose tolerance. This may be caused by a decrease of endogenous galactose production with ageing. Alternatively, suppression of endogenous galactose production by exogenous galactose might be implicated. The aim of this study was to determine if the rate of appearance of galactose is suppressed by exogenous galactose. Materials and methods. Two adult patients with classical galactosemia and three healthy control subjects were given a primed continuous infusion of D-[1-(13C])galactose to determine the rate of appearance of galactose (GAR, expressed as mmol/kg/h) before and during additional galactose supplementation. After initial assessment of GAR (GAR(1)), GAR was determined during doubled (GAR(2)) or quadrupled (GAR(4)) galactose infusion. Results. GAR(1) was 2.48 and 2.44 in patients 1 and 2, and 0.46, 0.34, and 0.39 in control subjects 1, 2, and 3, respectively. GAR(2) was 2.43 and 2.13 in patients 1 and 2, and 0.57, 0.38, and 0.47 in control subjects 1, 2, and 3, respectively. In patient 1 the experiment was repeated during quadrupled galactose infusion. Here GAR(1) was 3.01 and GAR(4) was 3.26. Conclusions. No significant differences between GAR before and during additional galactose infusion were found in patients and in control subjects. GAR, was significantly higher in patients than in control subjects. We conclude that the rate of appearance of galactose is not influenced by exogenous galactose, at least under short-term conditions, in patients with classical galactosemia and in control subjects. (c) 2004 Elsevier Inc. All rights reserved.