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Understanding the Basics of Acromegaly

Saima Andrabi   by Saima Andrabi, MS, Clinical Biochemistry    Last updated on July 30, 2019,

acromegaly overview

 

What is Acromegaly?

Acromegaly is a rare hormonal disorder that occurs when pituitary gland overproduces growth hormone in the body. Normally, growth hormone (GH) is produced by pituitary gland present in the brain but any kind of benign or non-cancerous tumor in the pituitary gland may result in excessive production of the growth hormone. Such non-cancerous tumors are called adenomas. Due to the overproduction of growth hormone, the bones of hands, feet and face become oversized. Acromegaly has been usually found in middle-aged adults, though it can develop at any age.

In case of growing children, overproduction of growth hormone can cause a condition called gigantism. Such children have exaggerated bone growth and an abnormal increase in height. Usually, acromegaly is uncommon and physical changes occur gradually, therefore, the condition sometimes takes a long time to diagnose. If not treated rapidly, acromegaly can result in serious illness and may even sometimes become life-threatening. There are many complications of acromegaly but the most serious ones are type 2 diabetes, high blood pressure, increased risk of cardiovascular disease, and arthritis. Acromegaly patients are also at an increased risk for colon polyps, which may develop into colon cancer if not removed immediately.

In case of children, the growth hormone producing tumors result in a condition called gigantism rather than acromegaly. Normally, a child's height is determined by the length of the long bones in the legs. In response to growth hormone, these bones grow in length at the growth plates. However, in case of adults, due to excessive growth hormone, height is not increased as the growth plates fuse after puberty. But prolonged exposure to excess growth hormone before the growth plates fuse causes increased growth of the long bones and thus increased height. Acromegaly generally affects muscle strength, bone health, and energy levels, and it can also lead to unusual physical features and medical complications.

Approximately, 3 to 4 people in every million receive a diagnosis of acromegaly in the United States each year, and it almost affects 60 people in every million at any time.

Fast Facts About Acromegaly

  • Acromegaly occurs due to overproduction of growth hormone in the body.
  • It can result in unusual physical features like swollen hands and feet, deformities, impaired muscle strength, and bone health.
  • The condition is most commonly caused by pituitary tumor, called pituitary adenoma.
  • Treatment options may involve a combination of surgery, radiotherapy, and medication to limit growth.

What are the Symptoms of Acromegaly?

One of the common signs of acromegaly is enlarged hands and feet. People with this disorder are often unable to put on rings that used to fit earlier and their shoe sizes increase progressively. Acromegaly also causes slow changes in the shape of face such as protruding lower jaw and brow, an enlarged nose, thickened lips, and wider spacing between the teeth. Since acromegaly tends to progress slowly, the early signs are not obvious for years.

Some of the main signs and symptoms of acromegaly, which can vary from person to person include:

  • Inflamed hands and feet
  • Coarsened and enlarged facial features
  • Coarse, oily, thick skin
  • Excessive body odor and sweating
  • Skin tags (Small outgrowths of skin tissue)
  • Fatigue and muscle weakness
  • Deep and husky voice due to enlarged vocal cords and sinuses
  • Severe snoring caused by obstruction of the upper airways
  • Impaired vision
  • Headaches
  • Enlarged tongue
  • Pain and limited joint mobility
  • Irregular menstrual cycles in women
  • Erectile dysfunction in men
  • Enlargement of organs like heart
  • Loss of interest in sex

The name acromegaly has been derived from Greek words for "extremities" and "enlargement," which reflect one of its most common symptoms i.e., the abnormal growth of the hands and feet. Swelling of the hands and feet is often an early feature, when patients notice a change in ring or shoe size, particularly shoe width. Increasingly, bone changes alter the patient's facial features like the brows and lower jaws protrude, the nasal bone enlarges, and the teeth space out.

Overgrowth of bones and cartilages often leads to arthritis in patients with acromegaly. Also, when the tissues thicken, they trap the nerves, resulting in carpal tunnel syndrome, which causes numbness and weakness of the hands. Besides, body organs get enlarged like the enlargement of heart.


Some other symptoms of acromegaly include:

  • Pain in the joints
  • Coarse, oily and thick skin
  • Enlarged lips and nose
  • Sleep apnea-breaks
  • Decreased libido

What Causes Acromegaly?

The acromegaly in adults is often associated with the overproduction of growth hormone caused by the tumor of pituitary gland, called pituitary adenoma. Pituitary adenoma or pituitary tumor is one of the most common types of non-cancerous or benign tumors of the pituitary gland. The tumor in the pituitary gland is one of the most important causes of acromegaly and results in the overproduction of growth hormone (GH), leading to abnormal growth.

Pituitary tumor is not inherent and can appear randomly due to a small genetic change of one cell within the gland. With time, this cell replicates and results in tumor formation called adenoma. Adenomas are non- malignant and do not spread to other parts of the body, but they can cause problems due to their size and location.

Due to the growth in the tumor, a pressure is developed on the surrounding brain tissues. Since the skull is a closed space, this growth can crowd the remaining tissue, and therefore result in headaches and vision problems. This tumor also effects the production of other hormones. The impact is different for men and women due to the type of hormone affected. Women may find that it affects their menstrual cycle while some men may experience sexual issues.

Usually, large pituitary adenomas cause excessive production of growth hormone. Around 17 % of the population has small pituitary adenomas that do not usually produce excess growth hormone or cause any symptoms.

Some other causes of acromegaly other than pituitary adenomas include:

  • Tumors in other other parts of the body like lungs, adrenal glands, or pancreas which results in an overproduction of GH and cause symptoms of acromegaly.
  • Increased growth hormone production somewhere outside the pituitary gland, such as from neuroendocrine tumors like small cell lung cancer or carcinoid tumors.

Complications of Acromegaly

With the progression of acromegaly, several major health problems can occur resulting in a large number of complications like:

An early treatment can help in avoiding the acromegaly complications and also prevent it from developing or becoming worse, however an untreated acromegaly and the associated complications can result in premature death.

How is Acromegaly Diagnosed?

The diagnosis of acromegaly is based upon the following:

Blood Tests

The elevated GH levels in a suspected person can be determined with the help of blood tests. But only the measurement of an elevated blood GH level is not enough to diagnose acromegaly because GH is secreted by the pituitary in impulses, or spurts, therefore its concentration in the blood can vary widely from time to time. Accurate information can be obtained by measuring the GH under conditions that normally suppress its secretion.

IGF Test

Growth hormone secretion by the pituitary gland into the bloodstream results in the production and  release of insulin-like growth factor-one (IGF-I) from the liver and other tissues. If growth hormone levels are high, IGF-I levels will also be high. Since IGF-I levels are much more stable over the course of a day than GH levels. This is often considered as a more reliable test. The IGF-I test has become the first test ordered to investigate excessive growth hormone secretion in many cases.

Glucose Tolerance Test

Usually, growth hormone production fluctuates widely throughout the day but is normally suppressed after consuming sugar-containing food or drinks. In case of patients with acromegaly, sugar consumption does not decrease the high levels of the hormone, as it does in patients without acromegaly. The glucose tolerance test is very reliable test and is usually done in initial investigations for the condition.

Acromegalic and Non-Acromegalic GH Levels

If acromegaly is confirmed from the results of the tests above, the following tests help in further diagnosis of the condition:

Pituitary Function

The non-tumor part of the pituitary gland is checked so as to find if it is functioning correctly. This is done with the help of some blood tests used to check the level of other pituitary hormones in the blood. If some of the pituitary hormones are found low or missing altogether they are replaced with specific hormones, pills or injections.

Scan

Scans are very important for checking the location and size of the tumor. Most commonly, MRI scans are used for this purpose.

GH and IGF-I Measurement

GH and IGF-I levels are measured in the blood to confirm the acromegaly and is usually confirmed by the elevated levels of these hormones in the blood.

Growth Hormone Suppression Test

This is one of the definitive methods for verifying acromegaly. Normally, glucose ingestion decreases levels of GH but if a person has acromegaly, the GH levels remain high.

Treatment of Acromegaly

The treatment of acromegaly usually focuses on lowering the production of GH, as well as reducing the negative effects of the tumor on the pituitary gland and surrounding tissues. A person may need more than one type of treatment. Some of the treatment options for acromegaly include:

Surgery

Surgeries like transnasal transsphenoidal surgery and endoscopic transnasal transsphenoidal surgery are used in the treatment of agromegaly. In transsphenoidal surgery, the doctors remove most of the pituitary tumors. Removing the tumor normalizes the GH production and eliminates the pressure on the tissues surrounding the pituitary gland to relieve associated signs and symptoms.

Medications

There are some drugs which can either lower the production of GH or block its action. Drugs that reduce excess growth hormone secretion are called somatostatin analogues and include octreotide (Sandostatin) and lanreotide (Somatuline Depot), which are the synthetic versions of the brain hormone somatostatin. These drugs interfere with the excessive secretion of GH by the pituitary gland and therefore decline the GH levels rapidly.

Besides, some other drugs which reduce the hormone levels are called dopamine agonists. These include some oral medicines like cabergoline and bromocriptine (Parlodel) .These drugs can also decrease the tumor size in some people, however some people may develop compulsive behaviors, such as gambling, while taking these medications.

There are also some drugs which can block the action of growth hormones and are called as growth hormone antagonists. The medication pegvisomant (Somavert) ia a growth hormone antagonist and has been found to block the effect of GH on body tissues. Pegvisomant is particularly helpful in people who haven't had a good success with other forms of treatment. This medication can normalize IGF-I levels and relieve symptoms in most people with acromegaly, but it cannot lower GH levels or reduce the tumor size.

Radiations

If some tumor cells remain even after the surgery, then radiation treatment is given to the patient. Radiation therapy destroys any remaining tumor cells and slowly reduces GH levels. However, it may take years for this treatment to noticeably improve acromegaly symptoms. Some of the types of radiation therapy include:

  • Conventional radiation therapy
  • Proton beam therapy
  • Stereotactic radiosurgery

Goals of Treatment for Acromegaly

The goals of treatment are to:

  • Reduce excess hormone production
  • Relieve the pressure exerted by the growing pituitary tumor on the surrounding brain areas
  • Preserve normal pituitary function and treat hormone deficiencies
  • Improve the symptoms of acromegaly

What you can Expect From Acromegaly Treatment

Once the treatment of acromegaly is successful, one can expect to notice that the hands and feet are now less swollen and have decreased in size. There is relief in the symptoms of carpal tunnel syndrome, facial features gradually returning towards normal, relief from excess sweating and type 2 diabetes. Headaches should improve and eyesight should return to normal. Life expectancy should be restored to normal with successful treatment.

What is Gigantism?

Gigantism is a condition found in children characterized by the overproduction of growth hormone (GH) which ultimately results in excessive growth. Gigantism causes abnormally high linear growth in children due to excessive action of insulin like growth factor I (IGF-I) because the epiphyseal growth plates are open during childhood.

Facts About Gigantism

  • Gigantism is caused due to excessive growth hormone production.
  • Excessive growth hormone (GH) production is almost always caused by a noncancerous or benign pituitary tumor.
  • Gigantism in children causes development of great stature.
  • Heart failure, weakness, and vision problems are common in gigantism.
  • It is often diagnosed with the help of some blood tests and imaging of the skull and hands.
  • Computed tomography (CT) or magnetic resonance imaging (MRI) of the head is done to look for the cause of gigantism.
  • A combination of surgery, radiation therapy, and drug therapy is used to treat the overproduction of growth hormone in gigantism.

What Causes Gigantism?

Gigantism is usually caused by a benign or non-cancerous pituitary tumor called as benign adenoma, which causes overproduction of growth hormone. Pituitary tumors can be either small in size (micro-adenoma) or bigger (macro-adenoma). There are some less common causes of gigantism like:

Mccune-Albright Syndrome

It causes abnormal growth in bone tissues, patches of light-brown skin, and some gland abnormalities.

Carney Complex

It is an inherited condition that causes benign or non-cancerous tumors in the connective tissue, cancerous or non-cancerous endocrine tumors, and spots of darker skin.

Multiple Endocrine Neoplasia Type 1 (MEN1)

It is an inherited disorder that causes tumors in the pituitary gland, parathyroid glands or pancreas.

Neurofibromatosis

It is an inherited disorder that causes tumors in the nervous system.

What are the Signs and Symptoms of Gigantism?

Children with gigantism are often much larger than other children of the same age. Also, some parts of their body are larger in proportion as compared to other parts. The symptoms of gigantism in children usually depend on the size of the pituitary tumor. As the tumor grows, it may compress the nerves in the brain.

The signs and symptoms of gigantism are usually due to overproduction of the growth hormone and also due to the pressure developed by the adenomas within or in the brain areas close to the pituitary gland. Therefore the excessive amount of growth hormone in children results in:

  • Tall stature
  • Prominent foreheads and jaws
  • Large hands and feet with thickened fingers and toes
  • Excessive sweating
  • Aches and pains in the joints (carpal tunnel syndrome)
  • Swelling in the soft tissues
  • Heart enlargement
  • Defective metabolism resulting in mild or moderate obesity, diabetes and high blood pressure
  • Headaches
  • Vision problems due to pressure on the optic nerves
  • Damage to the rest of the pituitary gland due to which it fails to produce other hormones called hypopituitarism
  • Delayed puberty

What is the Difference Between Gigantism And Acromegaly- Gigantism Vs Acromegaly

Both gigantism and acromegaly are rare syndromes characterized by overproduction of growth hormones (hypersomatotropism) and are nearly always caused by a pituitary tumor or pituitary adenoma. The difference between acromegaly and gigantism is that gigantism is found in children before fusion of the long bone epiphyses and therefore results in tall stature in such children as compared to the other children of the same age. Acromegaly is found in adults after the fusion of epiphysis and results in distinctive facial and other features.