Congenital hypothyroidism and immunodeficiency: evidence for an endocrine-immune interaction.

Bi-directional interactions between the endocrine and immune systems have been well described, particularly in relation to the growth hormone and adrenal axes. The possible effects of the thyroid gland on the immune system have not been clearly elucidated. This report describes a patient with congenital hypothyroidism and immune deficiency characterized by severe and persistent lymphopenia. The clinical course was punctuated by recurrent episodes of respiratory symptoms (in association with bronchiectasis) and diarrhea. The child ultimately died from overwhelming respiratory infection. It is proposed that the prolonged deficiency of thyroid hormone may be directly related to the impairment of the cellular immune system.