Anterior Pituitary (Adenohypophysis)

What is the anterior pituitary (adenohypophysis)?

The anterior pituitary, also called adenohypophysis, is the front lobe of your pituitary gland. This is a small, pea-sized gland located at the base of your brain, below your hypothalamus. It’s a part of your endocrine system and controls the function of several other endocrine glands.

Your pituitary gland consists of two lobes: the anterior (front) lobe and the posterior (back) lobe. The anterior pituitary creates and releases six different hormones, which regulate various bodily processes, including:

• Growth.
• Metabolism.
• Reproduction.
• Stress response.
• Lactation.

Despite its small size, your anterior pituitary is a mighty and busy gland. You can think of it like a conductor of an orchestra, directing several other glands and tissues in your body to make sure your hormones are working in harmony.

What are the anterior pituitary hormones?

The main function of your anterior pituitary is to produce and release (secrete) six hormones:

• Adrenocorticotropic hormone (ACTH): ACTH stimulates your adrenal glands to produce cortisol (the “stress hormone”) and other hormones.
• Follicle-stimulating hormone (FSH): FSH stimulates the testes to produce sperm, and stimulates the ovaries to prepare eggs for ovulation and release estrogen.
• Luteinizing hormone (LH): In women and people assigned female at birth (AFAB), LH triggers the ovaries to produce progesterone. In men and people assigned male at birth (AMAB), LH stimulates testosterone production.
• Human growth hormone (HGH): In children, HGH stimulates growth. In adults, it helps maintain healthy muscles and bones and impacts body fat distribution.
• Prolactin: This hormone stimulates breast milk production after giving birth and can affect menstrual periods, fertility and sexual function.
• Thyroid-stimulating hormone (TSH): TSH triggers your thyroid to produce and release its own hormones, which are essential for maintaining your body’s metabolic rate.

How does the anterior pituitary interact with other organs and glands?

Your anterior pituitary interacts directly with your hypothalamus. Your hypothalamus regulates it by secreting the “releasing hormones” somatostatin and dopamine through blood vessels in the pituitary stalk (the connector between your brain and pituitary). These releasing hormones either stimulate or inhibit (prevent) the creation and release of anterior pituitary hormones. Your hypothalamus and anterior pituitary are in constant communication with each other.

Once released, the anterior pituitary hormones interact with and affect several different organs, glands and tissues in your body, including:

• Bones, muscles and organs.
• Adrenal glands.
• Thyroid gland.
• Ovaries and testes (gonads).
• Mammary glands.

Where is the anterior pituitary located?

Your pituitary gland is located at the base of your brain, behind the bridge of your nose and directly below your hypothalamus. It sits in a small chamber or pouch in the sphenoid bone called the sella turcica.

Your pituitary gland is made of two lobes that touch each other. The anterior pituitary is in the front and faces the front of your head. The posterior pituitary is the back lobe of your pituitary gland, meaning it faces the back of your head. The anterior pituitary is bigger than the posterior pituitary and accounts for about 80% of the total weight of your pituitary gland.

What conditions are related to the anterior pituitary?

As it produces so many different hormones that control functions in your body, issues with your anterior pituitary can lead to many health conditions. In general, the majority of these conditions are due to hypopituitarism (underactive pituitary gland) or hyperpituitarism (overactive pituitary gland).

Hypopituitarism and hyperpituitarism generally happen because of one of the following conditions or situations:

• Pituitary gland tumors (adenomas).
• Damage to your anterior pituitary, hypothalamus or pituitary stalk through injury, infection or blood loss (pituitary apoplexy).
• Genetic conditions, like multiple endocrine neoplasia (MEN).

Hypopituitarism conditions

Conditions that are the result of lower-than-normal levels of one or more anterior pituitary hormones include:

• Secondary adrenal insufficiency: This happens when your anterior pituitary produces low levels of ACTH, which then makes your adrenal glands underactive.
• Growth hormone deficiency (GHD): GHD happens when your anterior pituitary releases lower-than-normal levels of growth hormone.
• Central hypogonadism: Central hypogonadism happens when sex glands (ovaries or testes) don’t produce enough sex hormones because your anterior pituitary releases lower-than-normal levels of FSH and/or LH.
• Central hypothyroidism: If your anterior pituitary releases too little TSH, it can cause central hypothyroidism (underactive thyroid).

Hyperpituitarism conditions

Conditions that are the result of higher-than-normal levels of one or more anterior pituitary hormones include:

• Acromegaly: Acromegaly is a rare condition that happens when the anterior pituitary produces too much growth hormone in adults. It causes your bones and tissues to grow in abnormal ways.
• Gigantism: Gigantism is a very rare condition that happens when a child or adolescent has high levels of growth hormone in their body, which causes them to grow very tall.
• Cushing disease: Cushing disease, a type of Cushing syndrome, happens when your adrenal glands make too much cortisol because your anterior pituitary releases excess ACTH.
• Hyperprolactinemia: This condition happens when your anterior pituitary releases too much prolactin.
• Central hyperthyroidism: If your anterior pituitary releases too much TSH, it can cause hyperthyroidism (overactive thyroid). This is a very rare cause of hyperthyroidism.

Pituitary adenomas

A pituitary adenoma is a growth or tumor on your pituitary gland. Most pituitary adenomas are slow-growing and benign (noncancerous).

Adenomas can put pressure on normal pituitary cells and keep them from working properly, leading to hypopituitarism, especially when they’re large. They can also release extra pituitary hormones, leading to hyperpituitarism.

Types of functioning (secreting) anterior pituitary adenomas include:

• Prolactinoma (excess prolactin). This is the most common type of pituitary adenoma.
• Somatotroph adenoma (excess GH)
• Corticotroph adenoma (excess ACTH).
• Thyrotroph adenoma (excess TSH).
• Gonadotroph adenoma (excess LH and FSH).

What tests can check the health of my anterior pituitary?

If you’re experiencing symptoms related to anterior pituitary issues, your healthcare provider may recommend tests to check one or more of your anterior pituitary hormone levels. These are usually blood tests.

If your test results come back abnormal, your provider may suggest undergoing an imaging test such as an MRI to take a look at your pituitary gland.

How can I keep my anterior pituitary healthy?

It’s not always possible to prevent anterior pituitary issues. But one thing you can do to keep it healthy is to protect your head. Head injuries and traumatic brain injuries (TBIs) can damage your pituitary gland, which can cause it to release too little or too many hormones.

Things you can do to try to prevent head and brain injuries include:

• Wear a seat belt every time you drive or ride in a vehicle.
• Practice safe driving habits.
• Wear a helmet when you ride a bike or motorcycle or play contact or extreme sports.
• Take steps to prevent falls, especially if you’re at a greater risk for them. This can include removing obstacles and tripping hazards in your home, using a walking aid and making sure you have clear vision.
• If you have children, make living and play areas safe for them.