In most patients, the source of excessive growth hormone (GH) secretion is a GH–producing adenoma of the anterior pituitary gland, usually macroadenoma (eosinophilic or mixed–cell). However, the cause of the tumor itself is unclear. Occasionally, hyperpituitarism occurs in more than one family member, suggesting a genetic cause.

Prolonged effects of excessive GH secretion include arthritis, carpal tunnel syndrome, osteoporosis, kyphosis, hypertension, arteriosclerosis, heart enlargement, and heart failure. Acromegaly may result in blindness and severe neurologic disturbances because of tumor compression of surrounding tissues. Both gigantism and acromegaly may also cause signs of glucose intolerance and clinically apparent diabetes mellitus because of the insulin–antagonistic character of GH.

The onset of acromegaly is gradual. The patient may report soft–tissue swelling and hypertrophy of the face and extremities at first. Then as the disease progresses, he may complain of diaphoresis, oily skin, fatigue, heat intolerance, weight gain, headaches, decreased vision, decreased libido, impotence, oligomenorrhea, infertility, joint pain (possibly from osteoarthritis), hypertrichosis, and sleep disturbances (related to obstructive sleep apnea).

Observation reveals an enlarged jaw, thickened tongue, enlarged and weakened hands, coarsened facial features, oily or leathery skin, and a prominent supraorbital ridge. You may also notice a deep, hollow–sounding voice, caused by laryngeal hypertrophy, and enlarged paranasal sinuses and tongue. Additional observations include irritability, hostility, and other psychological disturbances.