Hypopituitarism

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Hypopituitarism
(Pituitary Insufficiency)
Pronounced: Hi-po-pi-TUI-tar-ism
Definition
The pituitary gland is a pea-sized structure that is located at the base of the brain. It’s primary role is to produce hormones.
Hypopituitarism is an uncommon disorder caused when the pituitary gland does not produce enough of one or more hormones. The pituitary gland not only produces its own hormones, but stimulates other glands to produce hormones. When it isn’t functioning properly, it can cause the amount of hormones that other glands produce to diminish. This is a potentially serious problem that requires care from your doctor.
The pituitary gland is responsible for many body functions, including the following:
• Growth
• Blood pressure
• Sex organ function
• Thyroid gland function
• Breast milk production and other aspects of pregnancy
• Conversion of food into energy
• Water balance in the body
Pituitary Gland

Causes
There are several factors which may cause this condition:
• Tumors of the pituitary gland, hypothalamus, or brain
• Poor blood supply to the pituitary gland
• Head trauma
• Radiation to pituitary gland, head, or neck
• Stroke
• Infections and inflammatory diseases
• Uncommon immune system or metabolic diseases
• A rare complication after pregnancy, called Sheehan’s syndrome
• Metastatic cancer from lung, colon, prostate, or melanoma
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition. The risk factors for hypopituitarism include the following:
• History of childhood cancer (Treatment can damage the endocrine system, which controls hormones.)
• Infections
• Genetics
• Type 1 diabetes
• Sickle cell anemia
• Reduced blood volume or hypovolemia
Symptoms
Symptoms of hypopituitarism usually begin gradually and may not be recognized for a while. Symptoms depend on which hormone or hormones are low. The following are the hormones produced by the pituitary gland and their associated symptoms due to hormone deficiency:
• Growth hormone deficiency
o Poor overall growth
o Short stature
o Increased blood pressure
o Central obesity
o Muscle weakness
o Small heart
• Thyroid-stimulating hormone deficiency
o Sensitivity to cold
o Weight gain
o Constipation
o Hair that is brittle and coarse
o Heart rate slowed
o Dry skin
o Muscle weakness or fatigue
• ACTH (adrenocorticotropic hormone) deficiency
o Fatigue and weakness
o Low blood pressure
o Weight loss
o Increase in skin pigmentation
o Amenorrhea
• Follicle-stimulating hormone and luteinizing hormone deficiency
o Infertility
o Vaginal dryness
o Loss of some gender-specific sexual characteristics (ie, women lose axillary, body, and pubic hair)
o Reduced libido
o Amenorrhea
o Erectile dysfunction
o Muscle weakness
o Small testes
o Breast enlargement in men
Diagnosis
Your doctor will ask about your symptoms and medical history, and perform a physical exam. If necessary, your doctor will refer you to an endocrinologist, a doctor who specializes in treating hormone disorders.
Tests to determine hypopituitarism include taking a blood sample to do the following:
• Measure the levels of hormones produced by the pituitary gland
• Measure the levels of hormones produced by target endocrine glands, which are influenced by the pituitary gland
Provocative tests of pituitary function may also be done, including GHRH test, arginine stimulation test, insulin tolerance test, and ACTH stimulation test.
Once the diagnosis of hypopituitarism is confirmed, lateral skull x-ray imaging tests (eg, an MRI) are done on the pituitary gland to identify problems such as abnormal tissue and growth or shrinkage of the pituitary gland.
Treatment
Talk with your doctor about the best treatment plan for you. Hypopituitarism is permanent and will likely need to be treated for life. Treatment options include the following:
Surgery/Radiation Therapy
If the condition is caused by a tumor, surgery or radiation is usually the first treatment. Often, hormone replacement therapy is needed after these treatments.
Hormone Replacement Therapy
When hormone levels are inadequate, they must be replaced. In most cases, therapy does not replace the hormones that the pituitary gland produces. Instead, the hormones of the other glands that it stimulates are replaced. Examples include:
• Thyroid hormone for thyroid-stimulating hormone
• Corticosteroids for corticotropin
• Testosterone, estrogen, and progesterone for follicle-stimulating hormone and luteinizing hormone
• Growth hormone (the only pituitary hormone that is replaced)
Bromcriptine, Cabergoline, and Quinagolide
Hypopituitarism due to a prolactin-secreting tumor or prolactinoma responds well to several drugs (bromocriptine, cabergoline, or quinagolide) with success rates approaching 90%.
Prevention
In general, this condition is not preventable. However, being aware of the risks and symptoms will make early diagnosis and treatment possible.