Acromegaly is the result of a pituitary adenoma that produces growth hormone (GH). Growth hormone controls growth of the body. Elevated GH causes excessive bone and soft tissue growth. In children and adolescents it leads to gigantism. After puberty bones lose their ability to grow and therefore adults do not grow tall but develop acromegaly.
The average age at diagnosis is 40-45 years, but acromegaly can develop at any age. Because symptoms and signs are not always obvious, the diagnosis is usually delayed 10 to 15 years after the development of the condition.
The elevation of GH is caused in over 99% of cases by a benign tumor within the pituitary gland. GH-secreting adenomas account for 20% of all pituitary tumors. Seventy-five percent of GH-producing tumors are over 1 cm in size (macroadenomas). In a small number of cases, tumors of other organs (pancreas, adrenal, lung) may be the source of excess GH-releasing hormone which then stimulates the pituitary to secrete excessive quantities of GH.
Acromegaly is associated with many complications and may cause premature death. With successful treatment using a multidisciplinary team of endocrinologists and neurosurgeons, the complications and premature mortality can be avoided.
Since the effects of GH are different in children and adults, the symptoms of acromegaly vary by age.
In children, excessive growth is the usual presentation. If not treated, children can grow to a height of 7 or 8 feet.
Symptoms and complications in adults may include the following:
- Abnormally large growth and deformity of the:
- Hands (rings no longer fit)
- Feet (need a larger shoe size and width)
- Face (protrusion of brow and lower jaw)
- Jaw (overbite such that lower teeth close in front of upper teeth)
- Tongue (causing snoring and obstructive sleep apnea)
- Sinuses, vocal cords, and soft tissues of the throat Larynx (causing deep sonorous voice)
- Carpal tunnel syndrome (due to compression of the median nerve) giving rise to numbness and tingling and pain in the hand and arm
- Skin change:
- Thickened, oily skin
- Severe acne
- Excessive sweating and offensive body odor due to enlargement of the sweat glands
- Coarsening of facial features
- Fatigue and weakness in legs and arms
- Sleep apnea
- Arthritis and other joint problems particularly of the hips, knees and temporomandibular joint of the jaw
- Enlargement of the liver, kidneys, spleen, heart, and/or other internal organs
- Diabetes mellitus
- High blood pressure
- Cardiac disease – myopathy leading to heart failure
- Galactorrhea (abnormal production of breast milk)
- Gonadal dysfunction
- Colon polyps
In women, symptoms may also include:
- Irregular menstrual cycles or amenorrhea
In men, symptoms may also include:
- Erectile dysfunction, in about 50% of cases
A diagnosis of acromegaly is made by the doctor taking a full history and performing a physical examination. Review of photographs of the patient from years before will often allow the doctor to date the onset of the condition. Blood tests and imaging studies confirm the diagnosis of acromegaly.
Tests and positive results include:
- Insulin-like growth factor (IGF-I) blood test: IGF is growth hormone-dependent and is made primarily in the liver. The level is elevated in acromegaly and gigantism.
- Oral glucose tolerance test: This test determines whether GH levels suppress appropriately for a normal person and is the most reliable test for acromegaly. In this test, blood growth hormone levels are measured after drinking a glucose (sugar) drink. In patients with acromegaly, GH levels either do not suppress or increase. Depending on the clinical features and the IGF-1 level test results, however, an oral glucose test may not be necessary for a diagnosis.
Note on the growth hormone blood test: In some cases, the blood GH will be elevated; however, a single random GH level is not always helpful since it is secreted in a pulsatile fashion (increases and decreases at various times in a 24-hour day).
The goals of treatment are to:
- Restore production of GH to normal
- Stop and reverse the symptoms of acromegaly
- Correct other endocrine abnormalities (thyroid, adrenal, ovaries or testes)
- Remove and or destroy the tumor to restore endocrine function to normal and to relieve any symptoms directly related to the tumor (headaches, visual disturbance)
Drugs may be given to reduce the level of GH secretion. These include:
- Medications that act like dopamine (dopamine agonists):
- Cabergoline (Dostinex)
- Bromocriptine (Parlodel)may be given before surgery to shrink the tumor
- Sustained release preparations of somatostatin analogs given by intramuscular or deep subcutaneous injection
- Octreotide (Sandostatin)
- Lanreotide (Somatuline)
- Growth hormone antagonist
- Pegvisomant given by subcutaneous injection
In most cases, removal of the tumor through surgery is the preferred treatment. This can be done with a tranassphenoidal operation (through the nose) without disturbing the brain or the eye nerves.
After successful surgery
Once the tumor is removed, the imbalance of IGF and GH hormone will return to normal. However, IGF-1 levels may take several months before they become normal. Many of the symptoms of acromegaly will improve and patients are eventually able to sleep better and discontinue their medications for diabetes and high blood pressure. This usually takes weeks to months. Unfortunately, many of the physical changes do not revert back to their original appearance; however, certain features such as skin appearance usually improve.
Radiotherapy is most often performed after surgery has removed the majority of the tumor but some tumor remains which cannot be safely removed.
There are no known steps to prevent acromegaly. Early diagnosis allows for tumors to be diagnosed when they are small, which improves the chance of cure following surgery alone. Early treatment prevents the progression of irreversible effects, including changes in appearance, related to chronic GH overexposure.
Acromegaly can be treated effectively with surgical removal (depending on the size and location of the tumor) and medication. Because any type of pituitary tumor may recur, regular follow up with blood tests is necessary. If the blood tests show a return of a high IGF-1 hormone levels, an MRI scan is necessary. If a recurrent tumor is found, additional treatment is necessary.