Hyperpituitarism (Overactive Pituitary Gland)

Overview

What is hyperpituitarism (overactive pituitary gland)?

When your pituitary gland is overactive, it releases excessive amounts of certain types of pituitary hormones into your bloodstream. A noncancerous (benign) tumor in the gland, called a pituitary adenoma, is usually the cause of this condition. An overactive pituitary gland can cause a variety of disorders that affect growth, metabolism, reproduction and other vital body functions.

What does the pituitary gland do?

The pituitary gland plays a major role in controlling how your body works. It’s a pea-sized, cherry-shaped endocrine gland located near the base of your brain. Endocrine glands release (secrete) hormones into your bloodstream that control your body’s functions. Your endocrine system affects almost every cell and organ in your body. Sometimes the pituitary is called the “master gland” because it controls the activity of other endocrine glands. Most importantly, it controls the activity of your thyroid gland, adrenal gland and gonadal glands (ovaries or testes).

Think of your pituitary gland like a thermostat. The thermostat performs constant temperature checks in your home to keep you comfortable. It sends signals to your heating and cooling systems to turn up or down — and by how many degrees — to keep air temperatures constant. Your pituitary gland monitors your body functions in much the same way. Your pituitary gland sends signals to your organs and glands to tell them what functions are needed and when. The right settings for your body depend upon many things, including your sex, weight distribution and how active you are.

Blood vessels connect your pituitary gland to a part of your brain called the hypothalamus. Your brain tells your pituitary gland to increase or decrease the secretion of certain hormones.

Your pituitary gland consists of three parts: the anterior, intermediate and posterior lobes.

Anterior lobe

Your anterior lobe makes up about 80% of your pituitary gland and releases these hormones:

  • Adrenocorticotropic hormone (ACTH): This hormone causes your adrenal glands to produce steroid hormones, especially cortisol. Cortisol is the main stress hormone in your body, which keeps inflammation down and your blood pressure steady. You’re probably familiar with the role of cortisol in the “fight-or-flight” instinct.
  • Growth hormone (GH): This hormone regulates your body’s growth (especially in children), metabolism and body composition (such as how much fat, muscle and fluids you have).
  • Thyroid stimulating hormone (TSH): This hormone causes your thyroid gland to produce thyroid hormones that control how much energy you have.
  • Gonadotropins — luteinizing hormone (LH) and follicle stimulating hormone (FSH): These hormones cause the ovaries and testicles to secrete sex hormones needed for reproduction.
  • Prolactin: This hormone stimulates breastmilk production in people after they give birth.

Intermediate lobe

Your intermediate lobe secretes only one hormone:

  • Melanocyte-stimulating hormone: This hormone affects skin pigmentation.

Posterior lobe

Your posterior lobe stores and releases two hormones that your hypothalamus produces:

  • Antidiuretic hormone (ADH): This hormone controls water and electrolyte balance.
  • Oxytocin: This hormone manages uterine contractions during childbirth and the production and release of breast milk.

What pituitary disorders are associated with hyperpituitarism?

There are a number of adrenal disorders that can develop as a result of hyperpituitarism (overactive pituitary gland):

  • Cushing’s syndrome (hypercortisolism): If your pituitary gland secretes too much adrenocorticotropic hormone (ACTH), your adrenal glands may release too much cortisol. Besides being a “stress hormone,” cortisol manages the metabolism of proteins, fats and carbohydrates. It's also involved in your body’s inflammatory and immune responses.
  • Acromegaly: This disorder is a rare but serious condition that happens when your body releases high levels of growth hormone (GH) into your bloodstream, leading your bones and tissues to grow in abnormal ways.
  • Hyperthyroidism: If a pituitary tumor (adenoma) causes overproduction of thyroid stimulating hormone (TSH) (which is very rare), your thyroid gland will become hyperactive. This condition is also called overactive thyroid and can increase your metabolism, heartbeat rhythm and anxiety.
  • Hypothyroidism: If a pituitary adenoma causes your pituitary gland to make too little thyroid stimulating hormone (TSH), your thyroid gland may become hypoactive. Hypothyroidism caused by a noncancerous (benign) pituitary tumor is rare, but it can occur.
  • Prolactinoma: A benign tumor on your pituitary gland known as a prolactinoma may cause the gland to secrete too much prolactin. High levels of prolactin can disrupt normal reproductive function by interfering with hormones produced by the testicles or ovaries.

How common are hyperpituitarism (overactive pituitary gland) disorders?

Depending on the disorder, some are more common than others. Some of the most common conditions are:

  • Small benign pituitary tumors (adenomas): These are fairly common. About 10,000 are diagnosed in the U.S. each year. They may secrete excess amounts of hormones or be nonsecreting and not cause any symptoms.
  • Prolactinomas: Prolactinomas are the most common type of pituitary tumors, occurring in about 1 out of every 10,000 people. They’re more common in people assigned female at birth than people assigned male at birth.
  • Cushing’s syndrome: Cushing’s syndrome is a relatively rare disorder that occurs mainly in adults between the ages of 20 and 50 years old.
  • Acromegaly: Acromegaly is a rare disorder that occurs in only about 3 out of every 1 million people each year. It’s generally diagnosed in adults between the ages of 40 and 45.

Hyperpituitarism in children

Hyperpituitarism is rare in children. If it does occur, it typically results from pituitary microadenoma, a small (less than 10 millimeters), benign tumor. The most common pituitary adenoma found in childhood are prolactinomas, which occur in approximately half of all cases. Prolactinomas originate from stem cells of hormone-producing glands, which explains why they may secrete hormones. Several inherited syndromes — including multiple endocrine neoplasia type 1 (MEN1), Carney complex and familial isolated pituitary adenomas — appear to cause prolactinomas.

The disorders caused by prolactinomas depend on the sex and age of the child:

  • Children assigned female at birth may experience delays in puberty, loss of monthly periods (amenorrhea) and other symptoms of hypogonadism (failure of the ovaries to function properly). They produce less estrogen.
  • Children assigned male at birth are more prone to macroprolactinomas (large prolactinomas). Due to the size of macroprolactinomas, they tend to cause mass effect. This means the tumor presses on nerves and causes more neurological and ophthalmological issues (cranial nerve compression, headaches and vision loss). They can also experience puberty delays or growth issues.

Is hyperpituitarism (overactive pituitary gland) serious?

If left untreated, the conditions associated with hyperpituitarism can cause serious health problems. That’s why it’s important to talk to your healthcare provider if you experience symptoms of these disorders.

Symptoms and Causes

What are the symptoms of hyperpituitarism (overactive pituitary gland)?

The disorders related to an overactive pituitary gland have different symptoms.

Cushing’s syndrome (hypercortisolism)

Cortisol is necessary to keep your blood pressure and blood sugar levels even and also to help turn the food you eat into energy, among other important roles. But too much of a good thing can be bad, and that’s the case with the copious amounts of cortisol your body releases when you have Cushing’s syndrome.

Symptoms of Cushing’s syndrome may include:

  • Accumulation of fat in your upper body.
  • Excessive facial hair in people assigned female at birth.
  • Pink or purplish stretch marks on your belly (abdomen).
  • Tendency to bruise easily.
  • Bones may become fragile and tend to break more easily.

Acromegaly

Acromegaly occurs when your body produces more growth hormone than it needs. The extra growth hormone causes abnormal growth and other changes. Acromegaly can cause:

  • Enlarged or swollen hands and feet, causing an increase in shoe or ring size.
  • Change in facial structure: Your jaw and brow may stick out and your nose, tongue and lips may get bigger. Or you may see changes in the spacing of your teeth.
  • Skin that's thick, coarse and oily.
  • Irregular periods in people assigned female at birth.
  • Erectile dysfunction in people assigned male at birth.
  • Increased risk for high blood pressure, diabetes, heart attacks and certain types of cancer.

In children and adolescents, excessive levels of growth hormone can result in a condition called gigantism. Children with this condition may have unusually long arms and legs and may grow to heights of 7 to 8 feet or more.

Hyperthyroidism

If a benign pituitary adenoma causes your thyroid to release too much thyroid stimulating hormone (TSH) into your bloodstream, you may develop hyperthyroidism. Symptoms of hyperthyroidism may include:

  • Nervousness.
  • Rapid or irregular heartbeat (arrhythmia).
  • Weight loss.
  • Fatigue.
  • Muscle weakness.

Hypothyroidism

Rarely, a benign pituitary adenoma can cause your thyroid to not make enough thyroid hormone due to damage to normal pituitary gland cells. When this happens, you may develop hypothyroidism. Symptoms may include:

  • Brain fog.
  • Cold intolerance.
  • Constipation.
  • Dry, coarse hair and skin.
  • Decreased sexual interest.
  • Heavy, frequent menstrual periods.
  • Tiredness.
  • Weight gain.

Prolactinoma

If you have a benign tumor on your pituitary gland, it can cause too much prolactin to be released into your blood. Some symptoms — like headaches — are experienced by both sexes. When the prolactinoma is left untreated, it can grow large and press down on the optic nerve. This can cause impaired vision — or even blindness. Other symptoms depend upon your sex:

  • People assigned female at birth who aren’t pregnant or nursing may experience tenderness of their breasts and start to produce breast milk (galactorrhea). Their menstrual periods may become irregular or might stop altogether (amenorrhea). They may become infertile or lose interest in having sex. Having intercourse may be painful due to vaginal dryness.
  • People assigned male at birth may experience symptoms such as erectile dysfunction, a decrease in or loss of sex drive, decreased fertility or loss of energy. In very rare cases, they can experience galactorrhea (milky discharge from nipples).

What causes hyperpituitarism (overactive pituitary gland)?

Most cases of hyperpituitarism (overactive pituitary gland) are caused by a pituitary tumor. No one knows what causes these tumors but possible culprits include:

  • Benign tumors are the most frequent cause of an overactive pituitary gland. No one knows why these tumors occur. Depending on which types of cells it affects, your pituitary gland will start to secrete excessive amounts of one or two hormones.
  • In some cases, pituitary tumors may result from an inherited condition known as multiple endocrine neoplasia type 1 (MEN1). This disorder also causes benign tumors of your pancreas and parathyroid glands.
  • In rare cases, a cancerous tumor (carcinoma) or a disorder of your hypothalamus may be the underlying cause.

Diagnosis and Tests

How is hyperpituitarism (overactive pituitary gland) diagnosed?

Your healthcare provider will ask about your medical history and any symptoms you're having. Lab tests and scans may be ordered to measure the levels of hormones in your blood or urine or to detect the presence of a tumor. Tests may include:

  • For prolactinoma: Blood tests measure your prolactin levels. Hypothyroidism (an underactive thyroid) can also cause elevated prolactin levels, so these tests are done to rule out this possibility.
  • For acromegaly: Elevated blood levels of growth hormone (GH) cause acromegaly. Two blood tests are usually used to diagnose the condition. These include a test to check the level of the insulin-like growth factor-1 (which is a more stable marker for GH) and an oral glucose tolerance test.
  • For Cushing’s syndrome: Cushing’s syndrome can be challenging to diagnose. Several samples of your blood, cortisol level in saliva and urine may be needed to check for cortisol levels. Tests can determine other causes than Cushing’s disease, such as a tumor on your adrenal gland, or if cortisol levels are affected by use of anti-inflammatory drugs. Other tests include specialized invasive blood sampling, where blood is taken from the veins of your sinuses that drain blood from your pituitary gland.
  • For tumors: If lab tests suggest you may have a tumor, imaging tests can determine if this is the case, and if so, where the tumor is located and how big it is. Usually magnetic resonance imaging (MRI) is used. CT (computed tomography) scan may be used if you can’t have an MRI, such as if you have a pacemaker or other implant.

Management and Treatment

How is hyperpituitarism (overactive pituitary gland) treated?

Your healthcare provider may prescribe one or a combination of different treatments including:

Medication

Depending on your condition, you may simply be given medications to control your hormone levels. Your healthcare provider may use drugs to shrink large tumors before surgery or in cases where surgery isn’t an option.

  • For prolactinoma: Medication to reduce prolactin levels and potentially shrink the tumor is usually the first recommended treatment.
  • For acromegaly: Acromegaly may be treated with drugs used to lower growth hormone levels and shrink tumors along with surgical resection.
  • For prolactin-producing microadenomas: People with prolactin-producing microadenomas will usually receive dopamine agonist therapy medications as a first course of treatment for several months. Your provider will usually prescribe either cabergoline (Dostinex®) or bromocriptine (Cycloset®).
  • For prolactinomas: For people with prolactinomas — the most common kind of adenoma — 80% will have prolactin levels restored to normal. This often shrinks the tumor enough to improve vision, resolve headaches and restore menstruation and fertility. If unsuccessful, surgery is the next option.

Surgery

For acromegaly or Cushing’s syndrome: People with acromegaly or Cushing’s syndrome may undergo a surgical procedure called a transsphenoidal adenomectomy. To reach your pituitary gland and remove the tumor, your surgeon will make a small cut through your nose or upper lip. Though this procedure is very delicate, it has a success rate greater than 80% when performed by an experienced surgeon. Transsphenoidal surgery is most effective for small tumors (less than 10 millimeters, or ⅜ inch, in diameter). This procedure is considered safe, but all surgeries have risks, which your surgeon should talk about with you.

For prolactinomas: People with prolactinomas may need surgery to remove the tumor and take the pressure off their optic nerve. This may be done through your nose and sphenoid sinus (transsphenoidal surgery) or through open surgery (a craniotomy).

Radiation

Radiation may be used for people who can’t have surgery or who have some tumor tissue left after surgery which doesn’t respond to medication. There are two approaches to radiation:

  • Conventional radiation therapy: Conventional radiation therapy is given in small doses over a period of four to six weeks. However, radiation treatments can damage normal tissue surrounding the tumor.
  • Stereotactic therapy: Stereotactic therapy provides a high-dose beam of radiation targeted at the tumor. It can be done in one session, causing less damage to surrounding tissue. Most people who have radiation treatment need long-time hormone replacement therapy due to a gradual decline in the secretion of other pituitary hormones.

Is there a cure for hyperpituitarism (overactive pituitary gland)?

No cure is known for an overactive pituitary gland, but in many cases it can be treated and its symptoms managed.

Prevention

Is there a way to prevent hyperpituitarism (overactive pituitary gland)?

There's no specific way to prevent an overactive pituitary gland. However, your symptoms depend upon the disorder for which you are being treated. Since your health and symptoms vary on a regular basis, it’s important to take note of changes in how you feel. Keep in contact with your healthcare provider to stay ahead of any new or worsening symptoms of your condition. Keeping the communication lines open will help keep your condition in check.

Outlook / Prognosis

What is the outlook for people with overactive pituitary gland (hyperpituitarism)?

The outlook for an overactive pituitary gland is good for most people. Though some conditions may require you to take medications or be monitored on an ongoing basis, many people learn to manage their symptoms well and lead healthy, happy and productive lives. Rarer conditions, such as Cushing’s syndrome and acromegaly, need more serious treatment and outlooks are different for each person. If you have been diagnosed with prolactinomas — which tend to come back — you may require long-term medicines to control your condition and follow-ups with your healthcare provider.

A note from Cleveland Clinic

The hormone changes that come with hyperpituitarism (overactive pituitary gland) can disrupt your life. It might help if you keep a record of your symptoms, along with dates, and take this journal to your healthcare provider. If you’ve been diagnosed with any condition related to an overactive pituitary gland, tell your provider about any changes in symptoms or new symptoms that you experience.

Last reviewed by a Cleveland Clinic medical professional on 05/23/2022.

References

  • American Cancer Society. Pituitary Tumors. (https://www.cancer.org/cancer/pituitary-tumors.html) Accessed 5/23/2022.
  • Endocrine Society. Pituitary Tumors. (https://www.endocrine.org/patient-engagement/endocrine-library/pituitary-tumors) Accessed 5/23/2022.
  • Gounden V, Basit H, Jialal I. Hyperpituitarism. (https://www.ncbi.nlm.nih.gov/books/NBK482233/) [Updated 2022 Mar 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Accessed 5/23/2022.
  • National Association of Diabetes and Digestive and Kidney Diseases. Multiple pages reviewed for this article. (https://www.niddk.nih.gov/health-information/endocrine-diseases) Accessed 5/23/2022.

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