Increased levothyroxine requirements presenting as "inappropriate" TSH secretion syndrome in a patient with nephrotic syndrome

Patients with primary thyroid failure on levothyroxine (LT4) replacement wh o develop nephrotic syndrome (NS) may rarely present with an increase in LT 4 requirements. In this report, we describe a patient with thyroid failure following radioactive iodine ablation for Graves' disease who required an e scalation of LT4 doses following the onset of NS. The case presented with d isproportionately elevated TSH levels in the presence of normal(or slightly subnormal) thyroid hormone levels, thus, masquerading as a state of "inapp ropriate" TSH secretion. This pattern of extreme dysregulation in thyroid f unction indices due to urinary loss of thyroid hormones has not been previo usly described in NS, and, therefore, extends the spectrum of endocrine man ifestations of NS. (C)2000, Editrice Kurtis.