Hypouricemia in severely disabled children: influence of valproic acid and bed-ridden state.

Although hypouricemia does not directly elicit clinical symptoms, it is a sensitive indicator for detecting renal tubular involvement. To determine the influence of valproic acid (VPA) and a non-ambulatory state on the serum uric acid level in epileptic children, we performed a cross-sectional study of laboratory data including serum and urinary uric acid levels and renal tubular function levels in epileptic children. We studied 93 patients in our outpatient clinic. They were divided into four groups according to two factors; VPA administration and the ambulatory state: non-ambulatory patients taking VPA (24 cases), non-ambulatory patients not taking VPA (18 cases), ambulatory patients taking VPA (29 cases), and ambulatory patients not taking VPA (22 cases). The laboratory data including uric acid levels and renal tubular function in each group were analyzed statistically using analysis of variance. Both VPA (P<0.05) and a non-ambulatory state (P<0.01) significantly decreased the serum uric acid levels with its increased urinary excretion of uric acid. However, in ambulatory patients, the uric acid level was not decreased. Serum uric acid levels was significantly decreased in non-ambulatory, severely disabled children treated with VPA. It should be borne in mind that VPA-induced renal tubular dysfunction may be present in severely disabled children. However, further investigation is necessary to determine the factor in severely disabled children that causes hypouricemia