Pituitary Disorders

What the pituitary gland does

The pituitary sits in a bony pocket (the sella turcica) just below the brain and behind the nose, right under the optic nerves. Controlled by the hypothalamus, it releases hormones that regulate:

Types of pituitary disorder

Hormone-producing tumors

• Prolactinoma: the most common functioning tumor. Causes missed periods, milky nipple discharge and infertility in women, and low libido, erectile dysfunction and sometimes headaches or vision loss in men.
• Acromegaly: excess growth hormone in adults causes enlarging hands, feet and jaw, coarse facial features, sweating, joint pain, sleep apnea, diabetes and high blood pressure. In children it causes gigantism.
• Cushing's disease: excess ACTH drives cortisol overproduction, causing weight gain around the trunk, a rounded face, thin skin, purple stretch marks, muscle weakness, high blood sugar and blood pressure.
• TSH-secreting tumors: rare; cause hyperthyroidism.

Non-functioning adenomas

These do not produce hormones but can grow large enough to press on the gland and optic nerves, causing headaches, loss of peripheral vision and hormone deficiencies. They are often found in middle age.

Hypopituitarism

Hypopituitarism means reduced production of one or more pituitary hormones. Causes include tumors, surgery or radiation, head injury, severe bleeding during childbirth (Sheehan syndrome), pituitary apoplexy, infections, inflammation (hypophysitis, including from cancer immunotherapy) and genetic conditions. Symptoms depend on which hormones are low:

• low ACTH: tiredness, weakness, low blood pressure, low sodium; risk of adrenal crisis
• low TSH: tiredness, weight gain, feeling cold
• low LH and FSH: missed periods, infertility, low libido, erectile dysfunction
• low growth hormone: poor growth in children; fatigue and reduced muscle in adults (growth hormone deficiency)

Diabetes insipidus

Diabetes insipidus (now also called arginine vasopressin deficiency) causes extreme thirst and large volumes of dilute urine because of a lack of vasopressin. It can follow pituitary surgery or head injury.

Other conditions

• Pituitary apoplexy: sudden bleeding or loss of blood supply in a tumor; an emergency
• Craniopharyngioma: a tumor near the pituitary, often in children
• Empty sella: a flattened pituitary seen on scans; usually harmless
• Inherited syndromes: such as multiple endocrine neoplasia type 1

Diagnosis

• Hormone blood tests: prolactin, IGF-1 (for growth hormone), morning cortisol and ACTH, TSH and free T4, LH, FSH, estradiol or testosterone, and sodium
• Dynamic tests: stimulation tests for deficiencies and suppression tests (such as dexamethasone or glucose suppression) for excess
• Pituitary MRI with contrast
• Visual field testing by an eye specialist
• Water deprivation test for suspected diabetes insipidus

Treatment

• Medicines: - dopamine agonists (cabergoline) shrink most prolactinomas and normalize prolactin - somatostatin analogs and growth hormone receptor blockers for acromegaly - medicines that lower cortisol for Cushing's disease
• Surgery: transsphenoidal surgery through the nose removes most tumors, apart from prolactinomas, which are usually treated with medicine first
• Radiation therapy: for tumors that remain or return after surgery
• Hormone replacement: hydrocortisone, levothyroxine, sex hormones, growth hormone and desmopressin as needed
• Monitoring: small non-functioning adenomas found incidentally may simply be watched with MRI and hormone tests

Steroid sick-day rules

People taking hydrocortisone for ACTH deficiency need higher doses during illness, injury or surgery and should carry an emergency injection kit and medical alert identification, because adrenal crisis can be life-threatening.

Outlook

Most pituitary tumors are benign and controllable. Many people need lifelong hormone replacement and follow-up with an endocrinologist, but can live full, healthy lives.

Frequently asked questions

What are the symptoms of a pituitary disorder?

Symptoms depend on the type. Hormone-producing tumors cause specific syndromes, such as milky nipple discharge, enlarging hands and feet, or weight gain with stretch marks. Larger tumors cause headaches and loss of side vision. Hormone deficiencies cause tiredness, low libido, missed periods and low blood pressure.

Are pituitary tumors cancerous?

Almost all pituitary tumors are benign adenomas and do not spread. They can still cause problems by making excess hormones or pressing on nearby structures. Pituitary cancer is very rare.

What causes hypopituitarism?

The most common causes are pituitary tumors and their treatment with surgery or radiation. Others include head injuries, severe bleeding after childbirth, bleeding into a tumor, inflammation, infections, some cancer immunotherapies and genetic conditions.

How is a pituitary tumor treated?

Treatment depends on the type and size. Prolactinomas usually respond to cabergoline tablets. Other tumors that cause symptoms are usually removed through the nose (transsphenoidal surgery). Radiation and medicines are used if surgery does not cure the tumor.

Can pituitary problems cause infertility?

Yes. High prolactin and low LH and FSH stop ovulation in women and reduce sperm production in men. Treating the underlying problem, for example with cabergoline for prolactinoma, or with fertility hormones, often restores fertility.