Abnormal thyroid function tests in children on ethionamide treatment.

Ethionamide (ETH) treatment may cause hypothyroidism. Clinical data, serum thyroid stimulating hormone (TSH) and free thyroxine (fT4) levels were retrospectively assessed in 137 children receiving anti-tuberculosis treatment including ETH. Abnormal thyroid function tests (TFTs) were recorded in 79 (58%) children: elevated serum TSH and suppressed fT4 (n = 30), isolated elevated serum TSH (n = 20), isolated low serum fT4 (n = 28) and isolated low TSH (n = 1). The risk for biochemical hypothyroidism was higher for children on regimens including para-aminosalicylic acid and in human immunodeficiency virus infected children. TFT abnormalities are frequent in children on ETH and are mainly due to primary hypothyroidism or euthyroid sick syndrome.