POSTPARTUM THYROIDITIS AND FAMILIAL DYSALBUMINEMIC HYPERTHYROXINEMIA

Familial dysalbuminemic hyperthyroxinemia (FDH) is a syndrome associat ed with euthyroidism and increased binding of T-4 to serum albumin. Th e combined occurence of FDH and postpartum hyperthyroidism due to Grav es' disease has only been reported in one patient. We now describe the first case of FDH and thyrotoxicosis due to postpartum silent thyroid itis. In a 19-yr-old woman, FDH, suspected on the basis of strikingly elevated analog free T-4 (fT(4)) and total T-4 values, but normal two- step fT(4), and serum TSH values, was confirmed by [I-125]T-4 agarose- gel electrophoresis. When FDH and thyrotoxicosis, characterized by mar kedly elevated analog fT(4), total T-4, and two-step fT(4) values and undetectable TSH values, coexist, the differential diagnosis may be co nfusing.