[A study of the urinary acidifying capacity of patients chronically treated with anticonvulsants (author's transl)].

The subjects of this study were 18 patients with essential or secondary epilepsy under treatment with anticonvulsant drugs (hydantoins and phenobarbital) for periods of time varying between 8 months and 22 years. In all of them the serum levels of calcium, phosphorus, alkaline phosphatase, and the renal tubular capacity to acidify the urine were measured. Mean serum calcium and phosphorus levels were normal, while alkaline phosphatase was significantly elevated (p less than 0.0005). The renal threshold for bicarbonate was lowered to a mean of 23.01 +/- 2.86 (p less than 0.01). Distal tubular function was normal in all cases. When the patients are divided into two groups according to the duration of treatment (more or less than 100 months), the group with longest therapy shows an elevation of alkaline phosphatase (p less than 0.0005), a lowering of serum calcium (p less than 0.025) and a reduction of the renal threshold for bicarbonate (p less than 0.005) when compared to the group with shortest therapy.