Familial dysalbuminemic hyperthyroxinemia

Familial dysalbuminemic hyperthyroxinemia (FDH) rare genetic condition that is a common cause of euthyroid hyperthyroxinemia and is associated with mutations in the human serum albumin gene. It is an autosomal dominant condition that is often mistaken for resistance to thyroid hormone (RTH) syndromes or hyperthyroidism. FDH is characterized by high levels of thyroxine (T4) and normal levels of thyroid stimulating hormone (TSH). Due to the mutations in the albumin gene, an abnormal albumin protein binds thyroid hormones with a high affinity than normal. This explains why those with familial dysalbuminemic hyperthyroxinemia have increased T4 levels and normal TSH levels.