Severe congenital toxoplasmosis with isolated central hypothyroidism: A rare case report

Congenital toxoplasmosis results from transplacental transmission of <i>Toxoplasma gondii</i> during maternal primary infection. While the classic triad-hydrocephalus, intracranial calcifications, and chorioretinitis-defines severe forms, hypothalamic-pituitary axis involvement is extremely rare. Endocrine complications, particularly central hypothyroidism, are seldom described in this context. We report a preterm newborn at 35 weeks' gestation, representing the first documented case of isolated central hypothyroidism associated with severe congenital toxoplasmosis. Neuroimaging revealed major triventricular hydrocephalus, multiple cystic formations, and cerebral calcifications consistent with toxoplasmic meningoencephalitis. Ocular examination showed bilateral cataracts, microphthalmia, and retinal detachment. Laboratory studies confirmed congenital toxoplasmosis by positive IgM/IgG serology and cerebrospinal fluid PCR. Endocrine assessment demonstrated central hypothyroidism with low TSH (0.012 mIU/L) and T4 (4.31 pmol/L) levels, while exploration of the other hypothalamic-pituitary axes was normal, suggesting selective thyrotropic axis dysfunction. Treatment included pyrimethamine, sulfadiazine, folinic acid, and levothyroxine replacement. The infant died on day 54 of life from a nosocomial infection.This case highlights an exceptional presentation of congenital toxoplasmosis associated with isolated central hypothyroidism. The findings suggest potential inflammatory or vascular damage to the hypothalamic-pituitary axis. Early recognition and hormone replacement therapy are essential to prevent further neurological impairment. Systematic endocrine evaluation is recommended in neonates with severe central nervous system involvement due to congenital toxoplasmosis.