Pituitary Gland: Facts and Resources About Pituitary Tumors

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What Does the Pituitary Gland Look Like?

The pituitary gland is a small, reddish-brown endocrine gland. It is about the size of a pea and weighs approximately a half a gram. It is also known as the hypophysis or “master gland.” The pituitary gland derives the name “master gland” from the critical role it plays in the body. Despite its small size and weight, it is important in the functioning and control of the other endocrine glands in the body. The pituitary gland is located at the bottom of the hypothalamus and is connected to it by nerve tissue. It sits in a small bone cavity known as the “sella turcica” (literally “Turkish saddle” because the bone resembles a Turkish riding saddle).

All vertebrates have a pituitary gland. But the structure of the gland differs from species to species. This article presents only information about the pituitary gland in mammals, specifically in humans. For Example, the canine pituitary gland is slightly different.

Endocrine glands are located in different parts of the body. They release specific hormones directly into the blood stream and are not connected by any system of ducts or “pipelines.” Other endocrine glands are the pancreas, ovaries, testes, thyroid and the adrenal gland. Because of the pituitary’s importance, it is worthwhile to examine the structure of the gland and its functions.

The pituitary gland is comprised of three distinct sections. Each of the three sections is responsible for specific areas of activity and endocrine glands. The three sections of the pituitary gland are the anterior lobe, the intermediate lobe and the posterior lobe.

What does the Anterior Lobe Do?

The anterior lobe is responsible for the production of a number of hormones. The growth hormone regulates growth rates. If the pituitary gland produces too much of this hormone, the result can be the condition known as gigantism that results in excessive growth rates. People suffering from gigantism are prone to a range of other conditions as a result of their excessive height. The anterior lobe is also responsible for the production of prolactin that stimulates the production of milk in the mother following childbirth. Reducted prolactin can affect milk supply. Other significant responsibilities of the anterior lobe are the production of ACTH (adenocorticotropic hormone) that stimulates the adrenal gland, FSH (follicle-stimulating hormone) that plays a crucial role in stimulating the testes and the ovaries, TSH (thryroid-stimulating hormone) that affects the thryroid and LH (luteinizing hormone) that also affects the testes and ovaries.

What does the Intermediate Lobe Do?

The intermediate lobe is responsible for producing a hormone that stimulates the production of melanocyte that controls skin pigmentation. Lack of this hormone can result in varying degrees of albinism with its associated problem of exposure to UV radiation.

What does the Posterior Lobe Do?

The posterior lobe is primarily responsible for the production of two hormones. ADH (antidiuretic hormone) assists the kidneys by increasing the amount of water they can release into the blood supply. Oxytocin causes the uterus to contract during childbirth and also stimulates milk production by the mother.

The pituitary gland is thus responsible for many aspects of the body’s development and functioning. Problems within the pituitary gland can have far-reaching consequences for an individual’s health and life expectancy.

What is the Most Widespread Condition That Effects the Pituitary Gland

The most widespread condition that effects the pituitary is the development of usually benign tumors known as adenomas. In many cases, the adenoma may exist for many years without having any adverse effects on the pituitary and often without the individual being aware of its existence. Most pituitary tumors are noncancerous (benign). Up to 20% of people have pituitary tumors. However, many of these tumors do not cause symptoms and are never diagnosed during the person’s lifetime.

In those cases where the tumor does affect the pituitary, over half are situations in which the tumor exerts pressure on the pituitary. This can cause the gland to function with reduced efficiency and produce smaller quantities of hormones.

As a result, symptoms of one or more of the following conditions can occur

1. Hyperthyroidism
2. Cushing syndrome
3. Gigantism or acromegaly
4. Nipple discharge

Symptoms caused by pressure from a larger pituitary tumor may include

1. Headache
2. Lethargy
3. Nasal drainage
4. Nausea and vomiting
5. Problems with the sense of smell
6. Visual changes
a. Double vision
b. Drooping eyelids
c. Visual field loss

Treatment of a Pituitary Tumor

Treatment for most types of pituitary tumors is surgery, with access to the area being obtained through the nasal passages. Occasionally, radiation therapy is used as a follow-up to surgery.

The following medications may shrink certain types of tumors

1. Bromocriptine or cabergoline are the first-line therapy for tumors that release prolactin. These drugs decrease prolactin levels and shrink the tumor.

2. Ocreotide or pegvisomant is sometimes used for tumors that release growth hormone, especially when surgery is unlikely to result in a cure.

Can Chiari Malformation Affect the Pituitary Gland?

Chiari malformations (or CM’s) are physical imperfections in the cerebellum, the part of the human brain that is responsible for balance. The cerebellum sits at the lower rear part of the brain in a small indenture. However, in cases where the skull structure is smaller in this region, there can be pressure on the cerebellum. This condition, in turn, causes brain tissue to intrude into the spinal canal. This type of abnormal skull structure is a relatively rare occurrence. In addition, modern imagery technology has greatly enhanced the ability of doctors to identify its presence.

There are four types of chiari malformation. Type 1, the most common type, develops as the body grows. As a result, any effects may not be observable until the individual with the condition reaches adulthood. Type II chiari malformation is present at childbirth. It is a congenital disorder often found in infants suffering from spina bifida. In Type III chiari malformation, the back area of the brain can protrude from an opening in the rear of the skull. In Type IV malformation, the back of the skull fails to develop properly. All four types of chiari malformation are rare.

The exact causes of chiari malformation are uncertain. However it is thought to be caused by problems during the development of the fetus. Some researchers postulate that exposure to dangerous substances can cause the malformation to develop. Other researchers hold that a lack of vitamins, infection or excessive use of drugs or alcohol intake could be the cause.

Symptoms of chiari formation vary and can often be associated with other illnesses. Associated symptoms include headaches, difficulty in feeding and swallowing, neck pains, lack of strength in the arms, a decrease in feeling in arms and legs, breathing difficulties, rapid eye movements and a weak cry.

Diagnosing chiari malformation can be problematical as normal x-rays are not always capable of detecting the condition. Physicians attempt to obtain as thorough a medical and developmental history of the patient as possible. They will want to know details of the age at which the child began to crawl and to walk, when the child first sat up and if there were any abnormal developmental problems. The doctor may also take measurements of the child’s head in order to compare it with charts for age and gender norms. Almost always, any diagnosis will be made following the results of a magnetic resonance imaging (MRI) scan.

There is no direct evidence that links any of the types of chiari malformation with the pituitary gland and its functioning. There have been cases, however, of patients with Type I chiari malformation suffering also from pituitary tumors. The result of this conditon is problems with growth. Other chiari Type I patients experience reduced function of their pituitary.

There are many different treatments for chiari malformation but all involve some form of surgery. The basic surgical intervention involves freeing up the area at the base of the skull where the chiari malformation is found. This is done by removing a small portion of bone at the base of the cerebellum where it exerts pressure on the spinal cord and brainstem. The vast majority of chiari surgical interventions are successful with the child making a good recovery. However, the surgery is not a cure, merely a treatment. The child will need to be regularly monitored and tested throughout his or her lifetime.

Resources about the Pituitary Gland

University of Maryland Information about the Pituitary Gland from their Endocrinology Health Guide

The Pituitary Network Association

Information and Pituitary Gland Disorder Overview

Resource by T.Price

I am a mom of 2 boys who loves to spend time with them doing fun things outdoors. In my spare time I have my own things I enjoy doing such as gardening, reading old books, and being a closet history buff.

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