Table 1.

Common drugs used in metabolic disorders that can alter thyroid function tests and should be used with caution.

Metabolic disorder	Drug	Effect
Glucometabolic dysfunction	Metformin	↓ TSH levels in hypothyroid patients
	Pioglitazone	↓ TSH levels in hypothyroid patients
	Thiazolidinediones	Can induce thyroid-associated orbitopathy
Cardiometabolic dysfunction	Amiodarone	Can cause both hypothyroidism and thyrotoxicosis
	Beta blockers	↓ circulating T3 levels
	Prazosin	↑ TSH, ↑ T4, ↓ T3
	Sodium nitroprusside	Prevents hypothyroidism in patients undergoing coronary artery bypass grafting
Barometabolic disorders	Cholestyramine	↓TH levels; can impair levothyroxine absorption
	Colestipol	Transiently ↓T3 levels in some patients
	Statins	May have antiproliferative effect on thyroid cells; can alter thyroid size; effect of statin is lowered in TD
	Ezetimibe	Enhance conversion of T4 to T3
Viscerometabolic disorders	Interferon therapy used in liver and kidney diseases	Thyroid inflammation (both autoimmune and non-autoimmune), and either hyper- or hypothyroidism, which improve following discontinuation of interferon therapy
	Alemtuzumab used as induction agent in renal transplantation	Autoimmune Graves' disease
	Lenalidomide used in renal cancer therapy	Hypothyroidism or hyperthyroidism
	Sunitinib used in renal cancer therapy	Transient hypothyroidism
	Clomiphene citrate used in PCOS	Associated with increased risk of thyroid cancer

PCOS, polycystic ovary syndrome; T3, triiodothyronine; T4, thyroxine; TD, thyroid dysfunction; TH, thyroid hormone; TSH, thyroid stimulating hormone.