Pituitary Dysfunction

What the pituitary gland does

The pituitary, often called the "master gland", sits in a bony pocket below the brain, just behind the eyes and above the nose. Controlled by the hypothalamus, it releases hormones that direct other glands:

Types of pituitary dysfunction

Too little hormone (hypopituitarism)

Hypopituitarism means low output of one or more hormones. Symptoms depend on which are missing:

• low ACTH (cortisol): tiredness, weakness, weight loss, low blood pressure, nausea, and risk of life-threatening adrenal crisis during illness
• low TSH: tiredness, feeling cold, weight gain, constipation, dry skin
• low LH and FSH: irregular or absent periods, infertility, low libido, erectile dysfunction, hot flashes, loss of body hair, bone thinning
• low growth hormone: poor growth in children, and in adults reduced energy, increased belly fat and reduced muscle
• low ADH (diabetes insipidus): extreme thirst and large volumes of dilute urine

Too much hormone

Usually caused by a hormone-producing adenoma:

• Prolactinoma: the most common. Irregular or absent periods, milky nipple discharge, infertility, low libido and erectile dysfunction.
• Acromegaly: excess growth hormone in adults causes enlarged hands, feet and jaw, coarse facial features, sweating, joint pain and sleep apnea. In children it causes gigantism.
• Cushing's disease: excess ACTH drives cortisol up, causing weight gain in the face and belly, purple stretch marks, high blood pressure, diabetes and muscle weakness.
• TSH-secreting adenomas: rare, causing an overactive thyroid.

Pressure effects

A large tumor can press on nearby structures, causing:

• headaches
• loss of side vision in both eyes, from pressure on the optic nerves
• low hormone levels from pressure on normal pituitary tissue

Causes

• pituitary adenomas: noncancerous tumors, the most common cause
• surgery or radiation to the pituitary or brain
• head injury and subarachnoid hemorrhage
• pituitary apoplexy: sudden bleeding into or loss of blood supply to a tumor
• Sheehan syndrome: pituitary damage after severe blood loss during childbirth
• inflammation (hypophysitis), including from some cancer immunotherapy drugs
• infiltrative diseases such as sarcoidosis and hemochromatosis
• craniopharyngioma and other tumors near the pituitary
• genetic conditions causing low hormones from birth

Diagnosis

• blood tests: pituitary hormones and the hormones they control, such as cortisol, thyroid hormones, testosterone or estradiol, IGF-1 and prolactin
• dynamic tests: stimulation tests (for low hormones) or suppression tests (for excess hormones)
• water deprivation test for diabetes insipidus
• MRI of the pituitary with contrast
• visual field testing if a tumor is near the optic nerves

Treatment

Hormone replacement

• hydrocortisone for low cortisol, with extra doses during illness ("sick-day rules") and an emergency injection kit
• levothyroxine for low thyroid
• testosterone or estrogen for low sex hormones, and fertility treatment when pregnancy is desired
• growth hormone for children and some adults
• desmopressin for diabetes insipidus

Treating excess hormones and tumors

• dopamine agonists (cabergoline) shrink most prolactinomas without surgery
• transsphenoidal surgery: removing the tumor through the nose, the main treatment for most other symptomatic adenomas
• medicines that block growth hormone or cortisol when surgery does not cure
• radiation therapy or stereotactic radiosurgery for residual or recurrent tumors

People with low cortisol should wear a medical alert bracelet.

Outlook

Most pituitary disorders are very treatable. People with hypopituitarism need lifelong hormone replacement and regular monitoring but can lead normal lives. Most pituitary adenomas are benign and controlled with medicine or surgery.

Frequently asked questions

What are the symptoms of pituitary problems?

Symptoms depend on which hormones are affected. Low hormones can cause tiredness, weight changes, feeling cold, missed periods, low libido and infertility. Excess hormones can cause milky nipple discharge, enlarged hands and feet, or weight gain with stretch marks. Large tumors can cause headaches and side vision loss.

What causes pituitary dysfunction?

The most common cause is a benign pituitary adenoma. Other causes include surgery or radiation, head injury, bleeding into the gland, severe blood loss in childbirth, inflammation, and some cancer immunotherapy medicines.

Is a pituitary tumor cancer?

Almost always no. Pituitary adenomas are benign. They can still cause problems by making excess hormones or pressing on nearby structures, but they rarely spread. Pituitary cancer is extremely rare.

Can you live a normal life with hypopituitarism?

Yes. With the right hormone replacement and regular follow-up, most people live normal lives. People who need cortisol replacement must learn to increase their dose during illness and carry an emergency injection to prevent adrenal crisis.