Description, Causes and Risk Factors:
The pituitary gland is located in the middle of the head in a bony box that looks like a saddle and is called the sella turcica. Since the pituitary is in such a tight space, any abnormal growth can result in signs and symptoms secondary to compression of the gland. The nerves for the eyes pass directly above the pituitary gland.
Sometimes called the master gland, the pituitary gland plays a critical role in regulating growth and development, metabolism, and reproduction. This gland produces prolactin and a number of other key hormones including:
ACTH (adrenocorticotropin hormone) which stimulates the adrenal glands to produce cortisol, especially during stressful events (surgery, etc).
Thyroid stimulating hormone (TSH), which signals the thyroid gland to produce thyroid hormone; and Luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which regulate ovulation and estrogen and progesterone production in women, and sperm formation and testosterone production in men.
Growth hormone, which as the name indicates, regulates growth;
Adenomas which exceed 10 millimetres (0.39 in) in size are defined as macroadenomas, with those smaller than 10 mm referred to as microadenomas. Most pituitary adenomas are microadenomas, and have an estimated prevalence of 16.7% (14.4% in autopsy studies and 22.5% in radiologic studies). A majority of pituitary microadenomas often remain undiagnosed and those that are diagnosed are often found as an incidental finding, and are referred to as incidentalomas.
Although research continues to find causes of disordered cell growth, the sources of many pituitary adenomas, including prolactinomas, still remain unknown. Most pituitary adenomas appear sporadically, meaning that no one else in the family has had a pituitary adenoma.
Some patients with pituitary adenoma have a genetic disorder called multiple endocrine neoplasia type I (MEN1). MEN1 is an inherited condition characterized by a high frequency of peptic ulcer disease and abnormal hormone production from the pancreas, parathyroid, and pituitary glands. Pituitary adenomas are a characteristic feature of MEN1.
A small number of people have a familial tendency to develop pituitary adenoma but do not appear to have MEN1. The genes responsible for such cases of pituitary adenoma have not yet been fully identified.
Symptoms can vary quite a bit and may not be present at all. It will depend on whether or not the tumor is secreting hormones and how large it is. The tumor's location at the base of the brain can also cause symptoms.
General symptoms due to size may include:
Blurred vision or tunnel vision.
In addition to the above, symptoms from prolactin-secreting adenoma (40% of all cases):
Loss of or irregular periods.
Loss of sex drive.
Low bone density or osteoporosis.
Milk production from nonlactating females.
Symptoms from thyrotropin-secreting adenoma:
Enlarged thyroid (eg goiter).
Symptoms of hyperthyroidism:
Symptoms from corticotropin-secreting adenoma:
High blood pressure.
High fasting glucose.
Skin changes (increased facial hair, acne, bruising, bluish stretch marks.
Buffalo hump (increased fatty tissue in back).
Obesity especially around the wrist.
Growth hormone-secreting adenoma:
High blood pressure.
High fasting blood sugar.
Facial features coarse.
Your doctor will ask about your symptoms and medical history. A physical exam will be done. You will be referred to an endocrinologist. This is a doctor that specialized on glands and hormones.
Tests may include:
Urine tests—to measure excretion levels of certain pituitary gland hormones (beta human gonadotropin, cortisol).
Visual field tests—to check for problems with peripheral vision.
Glucose tolerance test—the standard test for acromegaly.
Blood tests—to measure pituitary and other gland (prolactin, thyroid-stimulating hormone (TSH), free thyroxine (FT4), insulin-like growth factor-1 (IGF-1), growth hormone, corticotrophin or ACTH, beta human gonadotropin, alpha subunit, estradiol, testosterone), hormone levels, blood sugar levels and to identify other underlying conditions that may be causing your symptoms.
Imaging: Adenomas larger than 4 mm can be reliably detected by MRI scans (using a special pituitary protocol). In some cases, a powerful 3-Tesla MRI (3T MRI) scanner may detect smaller tumors not visible using lower magnet strength scanners. Although larger adenomas can be seen on computed tomography (CT), an MRI scan is preferred.
The optimal treatment of a pituitary adenoma depends on multiple factors, including:
Size of the tumor.
How invasive the tumor is into surrounding structures.
The age and health of the patient.
Hormone production by the tumor (if present).
Hormone-producing pituitary adenomas should be treated in conjunction with an endocrinologist. Prolactinomas often require only medical (nonsurgical) therapy. For the majority of adenomas, that are prolactin or growth hormone secreting, medications may include:
Octreotide or long-acting versions.
Dopamine agonists (eg cabergoline, bromocriptine)
The vast majority of pituitary adenomas that require surgery are best removed through the nose. This minimally-invasive technique leaves no facial scar.
Radiation Therapy: Radiation therapy involves the use of radiation to kill tumor cells. The types of radiation therapy used to treat pituitary adenomas include:
Stereotactic radiosurgery — an intense radiation beam is targeted directly at the tumor.
Proton beam radiotherapy — a beam of protons (positively charged particles) is directly focused on the tumor.
Conventional therapy — radiation is directed at the pituitary from a source outside the body.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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