Hypopituitarism in Adults: Rational Approaches to Diagnosis and Treatment

Abstract Pituitary hormones are responsible for the regulation of growth, development, metabolism, reproduction, and homeostasis. Hypopituitarism is a condition that is defined as partial or complete insufficiency of anterior pituitary hormone secretion, and rarely, posterior pituitary hormone secretion. This condition can result from diseases of the pituitary gland or the hypothalamus. The annual incidence of hypopituitarism has been estimated to be 4.2 per 100,000 yearly, and the prevalence has been estimated at 45.5 per 100,000. The symptoms of hypopituitarism vary. The onset is insidious and depends on the number of hormone deficiencies and their degree of severity. Pituitary hormone deficiency can result in substantial clinical changes that increase the risk of morbidity and mortality. People commonly report persistent symptoms and a decline in their quality of life, both of which can be explained, at least in part, by the inherent shortcomings of hormone replacement strategies in their ability to imitate the normal hormone secretion processes. The diagnosis of hypopituitarism can be straightforward by measuring the lowered basal hormone levels. In cases where the basal hormone levels are uncertain or partial hormone deficiencies have been identified, it may be necessary to perform provocative testing of the hypothalamic–pituitary axis. The hypothalamus and pituitary region can be imaged using magnetic resonance imaging, which provides useful anatomical information. When necessary, genetic studies may be added to the diagnostic approach. The treatment consists of physiological replacement of the individual end-organ hormone deficiencies, and careful monitoring is required throughout the patient's entire life. Individualized hormone replacement therapy that considers potential interactions is recommended. This article provides an overview of the pathophysiology, clinical presentation, general diagnostic guidelines, and treatment options of hypopituitarism.