Acromegaly

A pituitary adenoma that continuously releases growth hormone (GH) drives the liver and other tissues to produce excess insulin-like growth factor-1 (IGF-1). IGF-1 is the major mediator of the visible tissue growth and the less visible cardiac, metabolic, and respiratory complications. The timing of GH excess determines the phenotype. Before epiphyseal plates close, excess GH causes gigantism through excessive linear growth. In adults, the plates are closed, so height does not increase. Instead, bone and soft tissue thicken: hands, feet, jaw, tongue, facial structures, and internal organs enlarge over years. The changes are gradual enough that patients may not recognize them. A comparison photograph, an old ring that no longer fits, or an increase in shoe size often reveals the pattern more clearly than a single examination.