Hypothyroidism: Pathophysiology and Management

Abstract

The thyroid plays an essential role in the homeostasis of the human body. Its hormones, thyroxine (T4) and triiodothyronine (T3), affect nearly every cell by regulating basal metabolism, protein synthesis, and growth and development. Hypothyroidism is a result of thyroid hypofunction. It can be described as a primary or central disorder. Primary disorders are dysfunctions of the thyroid gland itself, whereas central disorders occur due to disruptions in the HPT axis. Primary hypothyroidism has a higher incidence compared to central. It is predicted that 4.6% of Americans have hypothyroidism without knowing. Therefore, it is integral for healthcare providers to recognize and treat hypothyroidism to prevent morbidity. Clinical manifestations are nonspecific but play a role in determining the diagnosis, severity, and treatment strategies. Diagnosis is made with TSH and serum free T4 levels. Through adequate treatment, patients can achieve symptom resolution and euthyroidism. This chapter describes the epidemiology, etiology, pathophysiology, clinical manifestations, and treatments of hypothyroidism.