Acromegaly1
Acromegaly is the syndrome caused by growth hormone excess in adults and is due to a growth hormone- secreting pituitary adenoma in the vast majority of cases.
DIAGNOSIS
Clinical Presentation
Clinical findings include thickened skin and enlargement of hands, feet, jaw, and forehead.
Arthritis or carpal tunnel syndrome may develop, and the pituitary adenoma may cause headaches and vision loss. Obstructive sleep apnea and diabetes mellitus can develop. Mortality from cardiovascular disease is increased.Diagnostic Testing
• Plasma IGF-1, which mediates most effects of growth hormone, is the best diagnostic test. Marked elevations establish the diagnosis.
• If IGF-1 levels are only moderately elevated, the diagnosis can be confirmed by giving 75 mg glucose orally and measuring serum growth hormone every 30 minutes for 2 hours. Failure to suppress growth hormone to lt;1 ng/mL confirms the diagnosis of acromegaly. Once the diagnosis is made, the pituitary should be imaged.
TREATMENT
• The treatment of choice is transsphenoidal resection of the pituitary adenoma. Most patients have macroadenomas, and complete tumor resection with cure of acromegaly is often impossible. If IGF-1 levels remain elevated after surgery, radiotherapy is used to prevent regrowth of the tumor and to control acromegaly.
• The somatostatin analog octreotide in depot form can be used to suppress growth hormone secretion while awaiting the effect of radiation. A dose of 10-40 mg IM monthly suppresses IGF-1 to normal in about 60% of patients. Side effects include cholelithiasis, diarrhea, and mild abdominal discomfort.
• Pegvisomant is a growth hormone antagonist that lowers IGF-1 to normal in almost all patients. The dose is 10-30 mg SC daily. Few side effects have been reported, but patients should be monitored for pituitary adenoma enlargement and transaminase elevation.