Background: The aim of the present study was to investigate the effects of carbamazepine (CBZ), oxcarbazepine (OXC), and valproic acid (VPA) on thyroid function and volume in epileptic children.
Methods: Fifty-three epileptic children (age, 3-17 years) treated with OXC (n = 10), CBZ (n = 12), or VPA (n = 31) at least for 1 year were evaluated in terms of thyroid hormones, thyroid-stimulating hormone (TSH) levels, response to thyrotropin-releasing hormone (TRH) stimulation test, and thyroid volumes.
Results: The patients in the OXC and CBZ groups had similar total thyroxin (TT4) and free T4 (fT4) median levels that were significantly lower than those of the VPA group (P < 0.016). Total tri-iodothyrosin median levels were lower in the CBZ group compared to the VPA group (P < 0.016). Basal TSH levels and thyroid volumes were similar in all groups (P > 0.016). One child from the OXC group (10%), one from the CBZ group (%8.3), and six from the VPA group (19.3%) had hypothyroidic status according to the TRH stimulation test. No statistically significant correlations were found between thyroid gland volume and thyroid function variables and between anti-epileptic drug receiving time and thyroid function or thyroid volume, respectively, in any of the groups (P > 0.05).
Conclusions: Thyroid function should be evaluated periodically in children using CBZ, OXC or VPA. The children taking VPA seems to be at greater risk compared to children onr CBZ or OXC therapy. Except for the basal TSH values in the VPA group, the parameters predictive for the subclinical hypothyroid status remain to be evaluated in further studies.