Discordant thyroid function tests—beware of albumin variants

Abstract

amilial dysalbuminaemic hyperthyroxinaemia (FDH) is a benign euthyroid condition caused by albumin variants with increased binding affinity for thyroxine (T4). FDH falsely elevates T4 by common indirect/analogue methods confounding patient diagnosis. 1,2 Uncommonly, FDH may be present in a patient with Graves' disease, as seen in the case below, making interpretation of tests used for monitoring difficult.