ACROMEGALY

What is a gland?

1) A gland is an organ in a human or animal body that removes particular substances from the blood, changes them, and either secretes them for further use in the human body or gets rid of them. 2) A gland is typically composed of either cuboidal or columnar epithelium, located on the base of a membrane, and surrounded by a network of blood vessels. 3) The two different types of glands are the Endocrine glands (without ducts) and the Exocrine glands. 4) Endocrine glands secrete chemical substances (hormones) into the bloodstream rather than through ducts. (Pituitary gland is responsible for secreting the thyroid stimulating hormone to stimulate the hormone production of the thyroid gland. The thyroid gland is responsible for secreting thyroxine which increases metabolism so as to regulate growth and development.) 5) Exocrine glands disperse their products through ducts. (Mammory glands are responsible for dispersing breast milk. Sweat glands are responsible for dispersing sweat. Salivary glands are responsible for dispersing saliva.)

What is Acromegaly?

1) Acromegaly is a disease in which a benign (non-cancerous) brain tumor, or an adenoma, develops in one's pituitary gland, causing the pituitary gland to secrete too much human growth hormone (HGH). 2) When this occurs in an adult, the bones located in the body's hands, feet, and face will develop an abnormal increase in size.

What happens to children affected by acromegaly?

1) In the case of children affected by this acromegaly, excessive human growth hormone will cause them to develop gigantism. 2) In addition to the symptoms that affect adults with the disease (enlarged bone growth in hands, feet, and face), children will also have an abnormal increase in height.

What is the Pituitary Gland?

1) The pituitary gland is located at the base of the brain and is dorsal, or behind, the bridge of the nose. 2) The pituitary consists of two separate regions: the anterior lobe and the posterior lobe. The hormones produced by each lobe regulate the functions of other endocrine glands such as the thyroid gland, the adrenal glands, the ovaries, and the testes. 3) The pituitary gland receives messages from the hypothalamus regulating the production of hormones. The hypothalamus and the pituitary gland are joined to one another by the pituitary stalk (infundibulum). The anterior lobe of the pituitary gland produces its own hormones and releases them. The posterior lobe, however, does not produce its own hormones. The hormones themselves are produced by the nerve cells in the hypothalamus, which are responsible for regulating the posterior lobe to release their hormones into the body's circulation.

The Posterior Lobe

The Posterior Lobe releases two hormones; the Anti-diuretic hormone and Oxytocin. Anti-diuretic hormone is responsible for forcing the body's kidneys to ensure increased absorption of water into the body's circulation. Oxytocin, on the other hand, assists the female body in multiple processes, two of which are the contraction of the uterus to ensure the safe delivery of a child during birth and the regulation of breast-milk production.

What is a Somatotropinoma?

1) A Somatotropinoma is a common FIPA. These tumors produce another type of growth hormone called Somatotropin, which promotes growth of the body. 2) Somatotropinomas in children or adolescents can lead to increased height, or gigantism, because the arms and legs are still in a rapid period of growth. 3) In adults, growth of the long bones has already stopped, but the tumors can still cause overgrowth of the hands, feet, face, and other tissues, leading to Acromegaly.

What is Inherited Acromegaly?

1) An inherited pituitary adenoma is characterized as a Familial Isolated Pituitary Adenoma (FIPA). This is also a non-cancerous brain tumor in the pituitary gland. 2) These particular tumors are produced in the pituitary gland and release excessive amounts of one or more hormones whereas in other cases there are tumors that inhibit the pituitary gland's production of hormones (non-functioning pituitary adenomas). These tumors are distinguished by the hormones they produce.

The treatments for Acromegaly

The existing treatments for acromegaly include transsphenoidal surgery, somatostatin analogues, dopamine agonists, pegvisomant, and radiation. Transsphenoidal surgery is a procedure in which a surgeon enters through the patient's nose in order to remove the pituitary tumor. Removal of the tumor will normalize the body's GH level and relieve the pressure exerted by the tumor on the tissues surrounding the pituitary gland thus preventing severe headaches and impaired vision among other related symptoms. On occasion, the surgeon is able to remove the entire tumor, which might result in normalized GH levels after surgery and if that is the case, then they will most likely need to be treated using either medication or radiation. Somatostatin Analogues, Dopamine Agonists, and Pegvisomants are medications that can be used for the purposes of either lowering the body's production of HGH or by preventing it from acting on the Pituitary. Somatostatin analogues consist of Octreotide (Sandostatin) and Lanreotide (Somaltuline deposit), two of which are man-made versions of the brain hormone Somatostatin. Both of these are capable of disrupting the pituitary gland's excessive GH production, therefore leveling the body's GH level. When beginning to use Octreotide treatment, a patient must first inject their skin's subcutaneous layer of fat with a short term acting Octreotide three times a day to determine any side effects from the medication. If the effects of the injection are positive, then the patient is recommended to take a long-term acting form of Lanreotide that consists of an injection into the gluteal muscles, which are located in the buttocks. Dopamine Agonists consist of Cabergoline and Bromocriptine (Parlodel), which are administered as pills. The primary use of Cabergoline is to treat disorders that cause high levels of Prolactin production and are often the result of a pituitary tumor, like Acromegaly disease. Cabergoline is a dopamine receptor agonist that blocks the secretion of prolactin from the anterior lobe of the pituitary gland. Bromocriptine, on the other hand, is a medication that is normally used to treat Parkinson's disease as well as excessive abnormal breast milk production and assorted menstrual problems. This is often the result of too much Prolactin. The condition of too much prolactin is also referred to as Hyperprolactinemia. In addition to treating tumors that cause excessive prolactin production, it is also used to treat acromegaly. Similar to Cabergoline, it is also a dopamine agonist that lowers the body's level of human growth hormone. In some individuals, these drugs are capable of lowering levels of both HGH and IGF-I. Pelvisomants (Somavert) are growth hormone antagonists that have the function of blocking the effect of GH on the body's tissues. Pegvisomant is normally the last resort for individuals who haven't found any of the other treatments to change the effects of the disease. This medication is also to be administered by subcutaneous injection, which can reduce IGF-I levels to normal. However, it does not change the body's level of GH or reduce the tumor's size. Radiation therapy, which destroys any remaining tumor cells and lowers GH levels in the body, is recommended to people who still have tumor cells in their pituitary following a surgical procedure. Radiation treatment can be administered in three different ways; conventional radiation therapy, proton beam therapy, and stereotactic radio surgery. Conventional radiation therapy is normally administered every weekday over a period of four to six weeks. A patient may not fully develop the effects of this therapy until 10 years after treatment. Proton beam therapy delivers a focused high dose of radiation to the tumor without exposing other tissues to radiation. This therapy is provided in divided steps, over long intervals of time. Stereo static surgery, which is also referred to as Gamma Knife radio surgery, delivers a large amount of radiation to the tumors in one dose while limiting the amount of radiation exposed to the normal tissues. This type of treatment will normalize GH levels over a period of three to five years. Stereo static surgery is provided at very few medical centers in the U.S and Doctors do not recommend it to patients who are already receiving radiation therapy for acromegaly. Doctors determine the appropriate type of radiation treatment based on the factors of the size and location of tumor cells and the body's levels of IGF-I. Even following primary acromegaly treatment, the disease needs to be monitored periodically by a doctor to make sure that the pituitary gland functions properly. This monitoring is required for the rest of the patient's life.

What ages of people does acromegaly affect?

Acromegaly normally affects middle-aged adults between the ages of 40-45.

The diagnosis of Acromegaly

Diagnosing Acromegaly disease in an individual begins with a physical exam conducted by a Doctor. If, based on their observation, they suspect that you have the disease, they will first recommend an HGH and IGF-I measurement followed by a growth hormone suppression test and imaging. For the GH and IGF-I measurement, the doctor will take a blood sample to measure the GH and IGF-I levels after the patient has fasted overnight. If the levels of these hormones are above normal range, the diagnosis is acromegaly. For the growth hormone suppression test, blood levels of GH are measured both before and after the patient drinks a preparation of sugar, also referred to as glucose. Glucose ingestion should normally lower the body's GH levels. In the case of an individual with acromegaly, GH levels will remain very high even after glucose ingestion. This is the most efficient way for a Doctor to diagnose acromegaly. For imaging, the most common procedure is an MRI (magnetic resonance imaging), which identifies the exact location and size of the tumor in the pituitary gland. If the radiologist, the doctor who analyzes the images, finds no tumor in the pituitary gland, they might search for types of non-pituitary tumors that cause high GH levels.

What are the different types of FIPA tumors?

In a family that has the condition, members that are affected can either develop the same type of tumor (Homogenous FIPA) or different types (Heterogenous FIPA). In FIPA, pituitary tumors normally happen at a younger age than sporadic pituitary adenomas, which are not inherited. Normally, FIPA tumors are also larger than sporadic pituitary tumors. It is common that people with FIPA have macrodenomas, which are tumors larger than 10 millimeters.

The Cause of Acromegaly

In some cases, Acromegaly is hereditary, but the majority of adenomas are not inherited. The development of an adenoma is instead caused by a genetic change within a single cell in the Anterior Lobe of the Pituitary Gland. When that cell changes, it will in turn cause other cells in the anterior lobe to secrete more human growth hormone. The tumor will not spread to other parts of the body, but it will instead grow 1 cm in size and compress the nerves of the surrounding pituitary tissue, thus inhibiting the production of other hormones produced by the pituitary gland. Normally, when HGH is secreted into the body's bloodstream, it causes the body's liver to produce a hormone referred to as Insulin-like Growth factor-I (IGF-I). The IGF-I then stimulates bone growth and the growth of other tissues in the body. When the Pituitary Adenoma develops on the pituitary gland, it will produce an extra amount of HGH. Too much HGH secreted by the pituitary will in turn cause the liver to produce an excessive amount of IGF-I. This will in turn lead to the abnormal growth of the body's soft tissues and skeleton as well as the other symptoms of acromegaly and gigantism.

The Pituitary Adenoma

Pituitary tumors are the most common among the pituitary disorders. But in most cases, they are not necessarily life-threatening. However, they are still harmful, because pituitary tumors are also capable of interrupting the gland's function of releasing hormones. The three types of pituitary tumors are Adenomas, Craniopharyngiomas, and Rathke's Cleft Cysts. An Adenoma is benign tumor that is produced in Grandular Tissue. The tissues that it affects are primarily Epithelial Tissues. Epithelial tissues are the material that make up the body's skin, glands, cavities of organs, etc. The Epithelium originates from the Ectoderm, Endoderm, and Mesoderm in the Fetus. Adenoma cells do not need to be part of a gland, but might still possess secretory properties. Adenomas are normally non-cancerous, but are capable of becoming adenocarcinomas, which are cancerous. Large adenomas found in important hormone-producing organs increase the organs' production of those hormones, which in turn leads to Paraneoplastic Syndromes. Adenomas are capable of affecting such organs as the Colon, the Pituitary Gland, the Thyroid Gland, the Breasts, the Adrenal Gland, and the Kidneys. The Colon is the most common organ to be affected by an Adenoma. The Adenoma in turn can cause colon cancer. Adenomas that occur rarely tend to be those that affect the Liver, the Appendix, and Lungs. If the tumor is non-pituitary, it is located in either the lungs, the pancreas, or the adrenal glands. Occasionally, even these tumors will secrete GH. On other occasions, they will produce a hormone referred to as growth hormone-releasing hormone (GH-RH), which stimulates the pituitary gland to secrete more GH.

The Anterior Lobe

The Anterior Lobe produces and releases six hormones; the Adrenocorticotropic hormone (ATCH), the Follicle-stimulating hormone (FSH), the Luteinizing hormone (LH), Prolactin, the Thyroid-stimulating hormone (TSH), and the Human growth hormone (HGH). ACTH is a hormone that stimulates hormone production in the adrenal glands. FSH in collaboration with LH ensures that the body's ovaries and testes function properly. Prolactin is responsible for the production of breast milk. And TSH stimulates the Thyroid gland to produce hormones. The Human Growth Hormone (HGH) is highly important in the earlier years of people's lives, childhood in particular, so that the body can maintain healthy composition while in a rapid period of growth, whereas it assists adults by helping them to sustain health in their bones and muscle mass as well as regulating their fat distribution.

The symptoms of Acromegaly

When the adenoma secretes excessive amounts of human growth hormone, it will commonly lead to headaches and impaired vision. These two symptoms, in particular, are caused by the mass of the tumor pressing on the surrounding brain tissues. The disease can also cause other potentially severe health problems such as hypertension (high blood pressure), diabetes, obstructive sleep apnea (a failure to breathe during sleep), and carpal tunnel syndrome (pain, numbness, or tingling, in the hands or fingers). When Acromegaly disease goes untreated, there are other related health problems that have a potentially fatal outcome. One of these health problems is Organomegaly (excessive growth of of the body's organs), hepatomegaly (enlargement of the liver), splenomegaly (enlargement of the spleen), and cardiomegaly (enlargement of the heart). Cardiomegaly, in particular, increases the chances of dying by creating a greater susceptibility to heart disease. This issue, in combination with other related health problems, has the potential to considerably shorten life spans.