Dextrothyroxine treatment of phosphorylase-kinase deficiency glycogenosis in four boys.

Four boys, aged 2 years 5 months to 3 years 7 months, with large hepatomegaly due to phosphorylase-kinase deficiency glycogenosis, were given a trial of sodium dextrothyroxine (D-T4) at a mean dose of 0.165 mg/kg/day for an average period of 6 months. Phosphorylase-kinase was undetectable in the haemolysates of erythrocytes (3 patients) or in the liver (one patient) before, and still undetectable in the haemolysates of the four patients during treatment, thus pointing to X-linked phosphorylase-kinase deficiency glycogen storage disease (GSD IXb). D-T4 administration resulted in complete normalization of liver size, decrease of serum GOT (p less than 0.02), GPT (p less than 0.05) and triglycerides (p less than 0.01) to normal values, as well as correction of mild asymptomatic hypoglycemia (p less than 0.01). As long as the outcome of type IXb glycogenosis in adult life remains undefined, dextrothyroxine therapy seems an effective means of reducing liver size and correcting part of the biochemical abnormalities of the disease.