Hypothyroidism in infants with nephrotic syndrome.

Thyroid function indices were studied in five children with nephrotic syndrome in the 1st year of life. Four had primary hypothyroidism as defined by low serum free tri-iodothyronine (FT3) and free thyroxine (FT4), and high serum thyroid-stimulating hormone (TSH) levels. One patient with low serum FT3 and FT4 had a normal TSH level. T4 replacement therapy lowered TSH to normal levels in all four patients and normalized FT4 in three of them. There were no significant changes in serum FT3 levels. Adrenal function was studied in three patients, none had adrenal calcification or hypoadrenocorticism. This study supports the existence of a hypothyroid state in some infants with nephrotic syndrome. Routine thyroid screening and early replacement therapy is recommended.