Studies of Molecular Mechanisms Associated With Increased Deiodinase 3 Expression in a Case of Consumptive Hypothyroidism

Context: Consumptive hypothyroidism (CH) is a rare form of hypothyroidism due to increased catabolic activity of type 3 iodothyronine deiodinase (DIO3) that can occur in large tumors. Patients with CH typically present with markedly increased requirements for exogenous thyroid hormone and resolution after removal of the source of ectopic DIO3. DIO3 is encoded by DIO3, an imprinted gene expressed on the paternal allele that is located in a DIO3/delta-like 1 homolog (DLK1) gene locus regulated by a common control region, intergenic differentially methylated region (IGDMR). Because DIO3 is an imprinted gene, loss of imprinting at the IGDMR is thought to play a role in its increased expression; however, the molecular mechanism for DIO3 in CH currently is not known. Objective: The aim of the study was to determine the molecular mechanism for CH in an adult patient. Setting: The study was conducted in the Department of Endocrinology of a tertiary care center in Singapore. Patient: We report the case of an adult...