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Thyroid hormones in epileptic children receiving carbamazepine and valproic acid
A Verrotti1, F Basciani, S Morresi
1Department of Medicine, Section of Pediatrics, University of Chieti, Chieti, Italy.
Insights
Carbamazepine therapy in children with epilepsy may cause subclinical hypothyroidism, particularly when combined with valproic acid. Valproic acid monotherapy did not affect thyroid hormone levels.
Area of Science:
- Pediatric Endocrinology
- Neuropharmacology
- Thyroid Function
Background:
- Antiepileptic drugs (AEDs) like carbamazepine and valproic acid are crucial for epilepsy management.
- While generally well-tolerated, AEDs can impact endocrine function, necessitating careful monitoring.
- Previous reports suggest potential thyroid hormone alterations with AED use.
Purpose of the Study:
- To investigate the effects of carbamazepine and valproic acid on serum thyroid hormone levels in children with epilepsy.
- To evaluate thyroid hormone concentrations following thyrotropin-releasing hormone (TRH) stimulation.
- To differentiate the impact of monotherapy versus combination therapy on thyroid function.
Main Methods:
- Analysis of serum thyroid hormones (thyroxine, free thyroxine, triiodothyronine, free triiodothyronine, thyroid-stimulating hormone) in 37 epileptic children.
- Assessment of TRH stimulation test results.
- Comparison between groups receiving carbamazepine, valproic acid, or combination therapy, and a control group.
Main Results:
- Significantly lower serum thyroxine and free thyroxine levels were observed in children treated with carbamazepine and carbamazepine plus valproic acid compared to controls.
- Valproic acid monotherapy did not significantly alter serum thyroxine or free thyroxine levels.
- Serum triiodothyronine, free triiodothyronine, thyroid-stimulating hormone, and TRH responses remained comparable across all groups.
Conclusions:
- Carbamazepine treatment in children with epilepsy may be associated with subclinical hypothyroidism.
- Concomitant valproic acid use exacerbates these thyroid hormone changes.
- Valproic acid monotherapy does not appear to affect thyroid hormone levels, and hypothalamic function remains intact.
Abstract:
Carbamazepine and valproic acid are effective antiepileptic drugs for treating many types of epilepsy. Although they are well tolerated, many effects on endocrine function have been reported. Changes in serum thyroid hormones levels in 37 children with epilepsy during carbamazepine and valproic acid therapy were analyzed, and the thyroid hormone concentration after thyrotropin-releasing hormone test was evaluated. Serum thyroxine and free thyroxine levels were significantly lower in patients treated with carbamazepine and carbamazepine plus valproic acid than in the control subjects; serum thyroxine and free thyroxine concentrations were unaffected by valproic acid monotherapy. Serum triiodothyronine and free triiodothyronine concentrations were similar in the three groups of patients studied. Thyroid-stimulating hormone serum levels were normal in all patients, and the thyrotropin responses to the thyrotropin-releasing hormone were similar to control group. Our data suggest that children treated with carbamazepine may have subclinical signs of hypothyroidism, and these changes are more evident if carbamazepine is given in association with valproic acid, while no alteration in thyroid hormones can be found with valproic acid monotherapy. Thyroid-stimulating hormone and thyrotropin-releasing hormone levels do not seem to be affected by these drugs, suggesting that hypothalamic function is not affected in these children.