Pituitary Tumor – Causes, Diagnosis, Treatment

Pituitary tumor is (almost always) a benign tumor inside the pituitary gland. Often, it gives rise to symptoms due to its pressure on the surrounding structures and / or due to the hormone it produces. Before we discuss pituitary tumors, let me first explain what pituitary gland is and what are its normal function.

What Is Pituitary Gland?

Pituitary gland is a small structure, the size of a pea, located at the base of the brain, along a line that connects to the base of the nose. It consists of two lobes: anterior and posterior. Anterior pituitary lobe produces a number of hormones, which then control the function of most of the endocrine organs such as thyroid, ovaries, testes, and adrenal glands. In this way, pituitary gland is essential for the normal functioning of the human body. In fact, a person would not be alive if they don’t have pituitary gland.

Detailed illustration of the pituitary gland in the brain

Function Of  The Pituitary Gland?

The Pituitary gland controls the function of other endocrine glands by secreting several important hormones including:

• TSH (thyroid stimulating hormone)
• ACTH (adrenocorticotropic hormone)
• FSH (Follicle stimulating hormone)
• LH (luteinizing hormone)
• GH (Growth hormone)
• Prolactin
• ADH (antidiuretic hormone)

How Pituitary Gland Affects Our Body?

These pituitary hormones, in turn, control the function of several endocrine organs (the target organs) in the body.

• TSH regulates the production of Thyroid hormones (T4 and T3) by the thyroid gland.
• ACTH regulates the production of Adrenal hormones (cortisol and sex hormones) by the adrenal glands.
• LH and FSH regulate the production of Sex hormones and eggs by the ovaries in women and Sex hormones and sperm by the testes in men.
• GH regulates growth during childhood and puberty and continues to regulate the health of bones and muscles in adults.
• Prolactin regulates lactation in women.
• ADH regulates the urine concentrating ability of the kidneys.

Negative Feedback Mechanism

The target organ hormones control the production of pituitary hormones through a negative feedback mechanism. For example, if thyroid hormones (T4 and T3) are low, the pituitary gland produces a large amount of TSH, whereas production of TSH is diminished in response to a high level of thyroid hormones (T4 and T3).

How Emotions Affect Pituitary Function

Pituitary hormone production is also controlled by a higher center in the brain called the hypothalamus, which sits on top of the pituitary gland. In turn, hypothalamus is influenced by the other nearby areas in the brain, especially The Limbic System, which is an emotion-regulating center in the brain. This explains how the emotional state of a person can influence the function of the endocrine organs.

For example, women experiencing severe emotional trauma often stop having their menses. Here is the mechanism: Emotional stress suppresses the production of hypothalamic-hormone that controls the production of pituitary fertility hormone (LH and FSH). These hormones, then affect ovaries in such a way that egg maturation does not take place. In other words, nature has a fantastic mechanism to stop fertility if a woman is stressed out. Because child bearing happens when a woman is in good health, and not stressed out.

Pituitary Tumor

A Pituitary tumor is a small growth in pituitary gland. It is usually less than 10 mm. Sometimes it grows up to a more than 10 mm. While benign in most patients, pituitary tumor my  rarely be cancerous. When cancerous, it is usually due to metastases from a distant site such as cancer of  lung, colon, breast.

Now a days a pituitary tumor is often discovered incidentally on a brain CT or MRI scan.¹

A pituitary tumor may be hormone-producing tumors or non-hormone-producing.

Symptoms of Pituitary Tumor

A pituitary tumor may cause symptoms through one of the following mechanisms:

1. Pituitary tumor may produce one or more of the pituitary hormones. This type of pituitary tumor is called a functional or hormone -producing tumor.
2. Pressure of a large pituitary tumor on the surrounding brain structures can give rise to defects in the visual field, double vision and severe headaches.

Hormone-Producing Tumors

A pituitary tumor may produce one or more hormones as follows:

Prolactin Producing Tumor – Prolactinoma

A prolactin-producing tumor is the most common type of pituitary tumor. Medically speaking, we call it “Prolactinoma”. It often gives rise to a high prolactin level, which leads to a variety of symptoms. For example, a high prolactin level in women can give rise to milk production, menstrual irregularities or infertility. Whereas, in men, a high prolactin level can decrease testosterone level which in turn causes a decrease in libido, impotence and muscle weakness.

NOTE: High prolactin level is not always due to a pituitary tumor. There are multiple other causes of high prolactin level such as drugs, hypothyroidism, renal failure, breast manipulation, food, stress, etc.

You can learn more about high prolactin by clicking this link. https://doctorzaidi.com/prolactin-high-hyperprolactinemia/

Growth Hormone Producing Tumor

A Growth hormone producing tumor is rare. It can give rise to a disease state, known as Acromegaly.

ACTH (Adrenocorticotropic Hormone) Producing Tumor

An ACTH (adrenocorticotropic hormone) producing tumor is rare and may give rise to a disease state, known as Cushing’s syndrome.

TSH Producing Tumor

A TSH producing tumor is even rarer and can give rise to hyperthyroidism (overactive thyroid).

LH and FSH Producing Tumor

This type of pituitary tumor is rare. It can give rise to sexual symptoms in men as well as women.

Symptoms of a Pituitary Tumor Due to Underproduction of Pituitary Hormones

Symptoms of a pituitary tumor may also arise due to the local pressure effect of the tumor on the pituitary gland. Consequently, there may be under-production of the pituitary hormones. This condition is called Hypopituitarism.

What is Hypopituitarism?

Underproduction of pituitary hormones is known as hypopituitarism, which can result from the pressure effect of the pituitary tumor on the pituitary gland or due to surgery and/or radiation therapy of a pituitary tumor.

Hypopituitarism usually manifests as fatigue and muscle weakness due to low thyroid hormones, low cortisol, low growth hormone and in men, low testosterone level as well.

Treatment Of Pituitary Tumor

Management of a pituitary tumor is complex and must be carried out in consultation with an endocrinologist and neurosurgeon.

Evaluation of a pituitary tumor, which is carried out by an endocrinologist,  includes:

• Is the pituitary tumor producing a hormone or not?
• Is the pituitary tumor causing any pressure effects on the surrounding brain structures?
• Is there evidence of hypopituitarism?

Prolactin producing tumors are effectively treated with medications. Surgery is only rarely indicated.

Other pituitary tumors generally require surgery and at times, radiation therapy as well.

Hypopituitarism is treated effectively by replacing the deficient hormones. It is carried out by an endocrinologist.

Treatment of hypopituitarism is life-long.

In Summary

A pituitary tumor can give rise to a multitude of symptoms. An experienced endocrinologist is indispensable for proper evaluation and treatment plan.

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