Effect of antiepileptic drugs on thyroid function.
Chronic treatment with antiepileptic drugs (AED) is known to reduce serum thyroid hormone levels. Serum thyrotropin (TSH) level is unchanged despite low thyroxine (T4) level. We studied serum tri-iodothyronine (T3), T4 and TSH in 30 epileptic patients prior to discontinuation and 2, 4, 8 and 16 weeks after AED discontinuation. One AED was discontinued in each patient. Serum T3 levels were reduced consistently after AED discontinuation. Serum T4 and rT3 levels were increased, but not persistently. Serum TSH levels were unchanged. Our results suggest that during AED treatment serum T3 level was increased. This could be an increased conversion of T4 to T3. An acceleration of thyroid hormones degradation by enzyme induction is physiologically balanced by an increased conversion of T4 to T3.
Kimura
M
M
Department of Pediatrics, Nishitottori National Hospital, Tottori, Japan.
Yoshino
K
K
Suzuki
N
N
Maeoka
Y
Y
D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000009:adverse effects* / Q000627:therapeutic use; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D013960:Thyroid Function Tests; D013963:Thyroid Hormones / Q000097:blood*; D013997:Time Factors; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D000927:Anticonvulsants; D013963:Thyroid Hormones; D005723:gamma-Glutamyltransferase