Acromegaly

What it is

Acromegaly is broadening of the skeleton, which results from excess secretion of pituitary GH after epiphyseal closure; if the excess occurs before epiphyseal closure the result is gigantism. Growth hormone secretion stimulates hepatic release of IGF-1. In a child the growth is of the long bones, in an adult of the visceral organs.

The pituitary adenoma is one of the three tumors of MEN 1, the PPP row of the multiple endocrine neoplasms: parathyroid, pituitary adenoma, and pancreatic tumors secreting insulin, VIP or gastrin. These are all autosomal dominant, and when one is seen the others are thought of, especially in a young patient.

How it presents

The local tumor effect gives pituitary enlargement, visual field defects such as bitemporal hemianopsia, headache and cranial nerve defects. The facial features are frontal bossing and prognathism, with an enlarged, maloccluded jaw, coarse features and wide-spaced teeth, and the hat, ring and shoe sizes increase. Musculoskeletal and skin features are gigantism, arthralgias and arthritis, proximal myopathy, hyperhidrosis, skin tags and carpal tunnel syndrome. Cardiovascular features are cardiomyopathy, including hypertrophic cardiomyopathy, hypertension, heart failure and valvular disease such as mitral and aortic regurgitation. Pulmonary and gastrointestinal features are sleep apnea, narcolepsy, colon polyps or cancer, and diverticulosis. The enlarged organs are the tongue, thyroid, salivary glands, liver, spleen, kidney and prostate. The endocrine features are galactorrhea, decreased libido, diabetes mellitus, hyperparathyroidism and hypertriglyceridemia, with glucose intolerance and diabetes mellitus in 10% to 25% of patients; the hyperglycemia is mediated by growth hormone secretion stimulating hepatic release of IGF-1, through gluconeogenesis plus lipolysis and peripheral insulin resistance. A typical vignette is a young man newly diagnosed as diabetic and hypertensive with persistent headaches and blurring of vision, and features of acromegaly on examination are one of the signs suggesting secondary hypertension.