Overview
Gigantism is an uncommon medical condition characterized by unusually rapid and excessive growth during childhood and adolescence. It occurs when excess growth-promoting signals act on the body while the long-bone growth plates (epiphyses) are still open, producing increased height and enlargement of bones and soft tissues. For a general sense of the phenomenon of unusually large size, see growth and height.
Causes and biological mechanism
The principal biological driver of gigantism is prolonged overproduction of growth hormone (GH), usually from a benign tumor of the pituitary gland called a somatotroph adenoma. GH stimulates the liver to produce insulin-like growth factor 1 (IGF-1), which in turn promotes growth of bone and other tissues. Excess activity before closure of the growth plates leads to increased longitudinal bone growth. For more on the hormone involved, see growth hormone.
Signs, symptoms and complications
Children with gigantism present with accelerated height gain compared with peers and disproportionately large hands and feet. Other features may include coarsening facial features, delayed puberty, headaches, and visual disturbances if a pituitary tumor compresses nearby structures. Long-term complications can include joint problems, cardiovascular disease, insulin resistance or diabetes, and increased fracture risk.
Diagnosis and treatment
Diagnosis relies on clinical assessment supported by laboratory tests (elevated IGF-1, failure of GH suppression on glucose challenge) and imaging of the pituitary with MRI. Management typically aims to reduce GH production and its effects and may include:
- pituitary surgery (often transsphenoidal removal of the adenoma)
- medical therapy with somatostatin analogs or GH receptor antagonists
- radiation therapy when surgery and drugs are insufficient
History and distinctions
Clinical recognition of unusually tall individuals dates back centuries, but understanding of hormonal causes developed with modern endocrinology. Gigantism is distinguished from acromegaly, a related disorder caused by excess GH after growth-plate closure; acromegaly causes tissue thickening rather than tall stature. Gigantism remains rare, and timely diagnosis improves outcomes by limiting excessive growth and reducing associated health risks.