Definition
Acromegaly is a rare disorder of excessive bone and soft tissue growth driven by elevated growth hormone. In young children, before the growth plates fuse, excess growth hormone causes a similar condition called gigantism.
Causes
In most cases, acromegaly comes from over-secretion of growth hormone (GH) by a benign tumor of the pituitary gland, the small gland at the base of the brain that produces many hormones. In a small number of cases, malignant tumors of other organs (pancreas, adrenal, lung) are the source of excess GH.
Risk Factors
Some rare cases are hereditary. The average age of diagnosis is 40 to 45 years.
Symptoms
Symptoms develop very slowly, and untreated acromegaly can cause serious complications and premature death. In children, excess GH elongates the bones with associated soft tissue swelling; untreated, these children can grow to a height of 7 to 8 feet.
In adults, look for abnormal growth and deformity of the hands (rings no longer fit), feet (need a bigger shoe), face (protrusion of brow and lower jaw), jaw (teeth do not line up when the mouth is closed), lips, and tongue. Also carpal tunnel syndrome; skin changes (thickened, oily, sometimes darkened skin; severe acne; excessive sweating and body odor from enlarged sweat glands); a deepening voice from enlarged sinuses, vocal cords, and soft tissues of the throat; fatigue and weakness in the legs and arms; sleep apnea; arthritis and joint problems, especially in the jaw; hypothyroidism; and enlargement of the liver, kidneys, spleen, heart, and other internal organs, which can lead to diabetes, high blood pressure, and cardiovascular disease.
In women: irregular menstrual cycles and galactorrhea (abnormal breast milk production) in 50% of cases. In men: impotence in about 50% of cases.
Diagnosis
Blood tests measure insulin-like growth factor (IGF-I), growth hormone releasing hormone (GHRH), and other pituitary hormones. The two tests that anchor the diagnosis are an elevated IGF-I level and an oral glucose tolerance test: in a healthy person a 75 g glucose load suppresses GH, but in acromegaly the GH level fails to drop, which confirms abnormal GH hypersecretion (NIDDK). If these confirm acromegaly, imaging locates the tumor: head CT scan (an x-ray that uses a computer to image the brain and surrounding structures) and MRI scan.
Nursing Diagnosis
Disturbed body image related to anxiety over thickened skin and enlargement of the face, hands, and feet. Ineffective coping.
Treatment
Goals: reduce GH production to normal levels, stop and reverse the symptoms of over-secretion, correct other endocrine abnormalities (thyroid, adrenal, sex organs), and reduce tumor size.
Surgery. Surgical removal of the pituitary tumor, or other causative tumor, is the preferred treatment in most cases.
Radiosurgery. Highly focused external radiation beams shrink the tumor. Used most often when patients do not respond to conventional surgery or medications.
Radiation therapy. Used in combination with medical or surgical treatment.
Medication. Drugs work in three classes. Somatostatin analogs (octreotide, lanreotide), by injection, are the mainstay of medical therapy and lower GH secretion. Dopamine agonists, taken orally (cabergoline; bromocriptine, sometimes given before surgery to shrink the tumor), help in milder disease. Pegvisomant, a GH-receptor antagonist given by injection, is used when patients do not respond to other treatment. Note that pergolide (Permax), an older dopamine agonist, was withdrawn from the US market in 2007 over heart-valve risk and is no longer used. Medications are often combined with surgery or radiation to treat larger tumors affecting surrounding structures.
Prevention
There is no way to prevent acromegaly, but early diagnosis and treatment help prevent serious complications, some of which are irreversible.
Frequently Asked Questions
What causes acromegaly? In more than 9 of 10 cases it comes from a benign tumor (adenoma) of the pituitary gland that over-secretes growth hormone. Rarely, tumors elsewhere (pancreas, adrenal, lung) drive the excess. When the same hormone excess happens in a child before the growth plates close, it produces gigantism instead.
How is acromegaly diagnosed? Two tests carry the diagnosis: a blood IGF-I level, which stays elevated, and an oral glucose tolerance test, in which growth hormone fails to suppress after a glucose load (NIDDK). Once labs confirm the excess, an MRI of the pituitary locates the tumor.
Why do symptoms take so long to notice? Bone and soft tissue enlarge slowly over years, so changes creep in. Patients often realize their rings, shoes, hats, or dentures no longer fit before anyone names the disorder, which is part of why diagnosis is commonly delayed several years.
What is the main treatment? Surgical removal of the pituitary tumor is the preferred first-line treatment in most cases. When surgery cannot fully control the disease, somatostatin analogs, dopamine agonists, the GH-receptor antagonist pegvisomant, or focused radiation are added.
What is the difference between acromegaly and gigantism? Both come from too much growth hormone. Acromegaly occurs in adults after the growth plates have fused, so bones thicken rather than lengthen. Gigantism occurs in children before the plates close, so the long bones keep growing and height increases dramatically.
Can the changes be reversed? Some soft-tissue swelling improves once growth hormone is controlled, but bony enlargement and joint damage are often permanent. That is why catching it early matters, and why untreated acromegaly raises the risk of diabetes, hypertension, and cardiovascular disease.