SLC25A5 and hyperthyroxinemia: It may be distinguished by a pituitary MRI (abnormal in TSH adenoma) and measurement of glycoprotein alpha subunit to TSH ratio (elevated in TSH adenoma). Similarly, other differentials include increased serum-binding proteins, familial dysalbuminemic hyperthyroxinemia, the presence of anti-iodothyronine (anti-T4, anti-T3) antibodies, or certain drugs such as amiodarone and beta-blockers [5].