Thyroid hormones exert their effect on all tissue and modulate the rate of metabolic activity appropriate for each situation. As a result of their actions, alterations in thyroid function can affect the liver and perturb measures of hepatic function and injury in the absence of liver disease. These alterations in the measure of hepatic function and injury may be difficult to recognize as being caused by thyroid dysfunction rather than hepatic disease. As a result, they may be quite troublesome for patients and physicians if their cause is not properly identified. Importantly, abnormalities in liver function tests return to normal once the primary thyroid pathology is recognized and treated.