Abstracts

RATIONALE: Low serum sodium have been reported during carbamazepine (CBZ) or oxcarbazepine (OXC) medication. In our previous study polytherapy and female gender seemed to increase the risk of hyponatremia. Therefore we aimed to evaluate whether hyponatremia during CBZ and OXC medication is associated with altered serum sex hormone levels. METHODS: 116 randomly selected patients taking CBZ or OXC for epilepsy participated in the study. Female subjects were in the early follicular phase of the menstrual cycle and were not pregnant, lactating or receiving oral contraceptives. Serum sodium, sex hormone binding globulin (SHBG), estradiol (E2) and testosterone (T) levels were measured. RESULTS: Serum sodium levels were lower in the female patients than in the male patients (p<0.05) on CBZ or OXC medication. In the female patients, who had serum sodium levels below the reference range the serum concentrations of SHBG (146.1 57.4 nmol/l) were higher than in female patients (104.4?41.8 nmol/l) with serum sodium levels within the reference range (p<0.05). However, serum E2 and T concentrations were similar in both female patient groups. On the other hand, in male patients serum SHBG, E2 and T concentrations were similar regardless of they had decresed serum sodium levels or not. CONCLUSIONS: Female patients with low serum sodium levels had elevated serum SHBG concentrations. Thus drug induced alterations in the bioactivity of sex steroids may play a role in the pathogenesis of drug related hyponatremia.