Triiodothyronine and thyroid-stimulating hormone in protein-calorie malnutrition in infants.

Protein-calorie malnutrition (P.C.M.) in a group of 43 Senegalese children aged eighteen to thirty months was characterised by a sharp fall in serum-triiodothyronine (T3) concentration to 25-3% of the mean value in healthy age-matched controls. This decrease in T3 was significantly (P less than 0-001) more pronounced in kwashiorkor of recent onset than in long-term P.C.M., a finding which suggests that impaired thyroxine (T4) monodeiodination in the liver was responsible for the fall in serum-T3 concentration rather than a reduction in the secretion of T3 by the thyroid. Serum-T3 concentrations became normal in both malnourished groups after two weeks of appropriate nutrition. Serum-T3 concentrations in healthy, euthyroid, Senegalese children were higher than in White children. In frank kwashiorkor in Senegalese children, serum-thyroid-stimulating-hormone (T.S.H.) concentrations were within the normal range throughout the entire course of dietary therapy, indicating that the children remained euthyroid. In contrast, protracted P.C.M. led to impairment of the T.S.H./T3 feedback mechanism and to a condition resembling hypophysectomy, which required two weeks' dietary therapy for its correction.