Saturday, February 11, 2017

The pituitary gland

No one talks much about the pituitary gland. That is strange, since the pituitary gland is the commander in chief of many vital functions of the body.
The pituitary gland is located in the center of the head, below the hypothalamus.
The pituitary gland has two sections, the anterior pituitary and the posterior pituitary.
The anterior pituitary is composed of cells that produce certain hormones upon control of the hypothalamus, which in turn modulates the system based on the feedback messages from the body. These hormones control the adrenal system ( adrenocorticotropin hormone or ACTH), the thyroid system ( thyroid stimulating hormone or TSH) , the gonadal axis ( luteinizing hormone LH,  follicle stimulating hormone or FSH). The pituitary gland also produces Prolactin,  Growth Hormone (GH), melanocyte stimulating hormone (MSH) and alpha subunit.
The posterior pituitary gland is composed of nerve endings that control sodium/water balance (through the antidiuretic hormone or  ADH) and multiple other reflex functions of the body (oxytocin).
The most common disorders of the pituitary gland are adenomas. Adenomas are benign tumors that secrete in excess one or more of the pituitary hormones and are not subject to the normal feedback controls of the body. The most common one is called prolactinoma. A prolactinoma secretes prolactin in excess. It usually presents with breast milk discharge in a woman that is not pregnant. In a man, it may present with breast enlargement. This benign tumors can grow to cause pressure in the optic nerve that crosses above the pituitary gland. When that happens the person may experience blindness in peripheral vision. Prolactinomas are one of the few tumors that can be shrunk with medication and does not need surgery.
Pituitary tumors of other kinds usually present with elevated prolactin but not as high as with a prolactinoma. Because prolactin inhibits sexual hormones, the patient may complain of no periods if female, or impotence if male.
Some pituitary tumors may cause disorders of metabolism that cause typical body changes, such as acromegaly ( GH excess) and Cushing's disease ( ACTH excess). These usually require surgery to remove the tumor.
Other tumors, occur more commonly in older patients, do not secrete hormone but are more likely to grow so that it causes a problem due to size. Patients may present with peripheral blindness or headaches.
Patients that experience these problems should discuss them with their primary care doctors and a prolactin level should be done. It is usually elevated when a pituitary tumor is present.