Abstracts

Rationale: To determine abnormalities in thyroid function in patients with epilepsy using traditional antiepileptic drugs (AED) in mono or polyteraphy and their correlation with the AED blood levels. Methods: We prospectively performed serum thyroid stimulating hormone (TSH), thyroxine (T4), triiodothryronine (T3), free thyroxine (fT4) and free triiodothryronine (fT3) and AED levels in 89 patients with epilepsy attending the Epilepsy Clinic at the National Institute of Neurology and Neurosurgery, Mexico city, patients were taking valproate (VPA), carbamazepine (CBZ) or phenytoin (PHT) in mono or polytherapy. Results were analyzed using student t test for parametric variables and Mann-Whitney U-test and Spearman correlation for nonparametric variables. Results: TSH was elevated in patients taking valproate in mono (p =0.03) or polytherapy (p=0.010). VPA monotherapy increases fT4 (p= 0.023) while VPA polytherapy increases T4 (p=0.037). Carbamazepine in monotherapy and polytherapy reduced fT4 (p= 0.003 & p = 0.009 respectively). Phenytoin monotherapy decreased T4 (p=0.05) and PHT polytherapy increases fT4 (p = 0.009). There was a positive correlation between VPA blood levels and increase of TSH and fT4 levels (p 0.01). We did not find a correlation between the time taking AED and the presence of thyroid abnormalities. Conclusions: Our study shows that the use of traditional AED in mono or polytherapy produces significant thyroid abnormalities. The use of VPA associates with an increase of TSH and fT4 that also correlates with VPA blood levels. It is important to identify these cases, evaluate them for treatment and eventually determine the clinical relevance of thyroid abnormalities in patients taking AED.