The pituitary gland â often called the "master gland" â is a pea-sized structure at the base of the brain that controls the activity of most other hormone-producing glands in the body. Pituitary disorders affect not only the pituitary itself but also the downstream glands it regulates.
The Pituitary Gland's Role
The pituitary produces several key hormones:
| Hormone | Target/Function |
|---|---|
| TSH | Stimulates the thyroid to produce T4/T3 |
| ACTH | Stimulates the adrenal glands to produce cortisol |
| LH/FSH | Regulate the gonads (ovaries/testes) |
| GH (Growth Hormone) | Stimulates growth, metabolism |
| Prolactin | Stimulates milk production; also affects reproduction |
| ADH (Vasopressin) | Controls water retention by the kidneys |
| Oxytocin | Uterine contractions, bonding |
Pituitary Adenomas
Pituitary adenomas are benign tumors of the pituitary gland. They are common â found in up to 15% of people on MRI â though most are small and cause no symptoms. Adenomas can be:
- Non-functioning: Do not secrete excess hormones; may cause problems by compressing the normal pituitary or nearby structures
- Functioning: Secrete excess hormones â the type of adenoma is named for the hormone it produces
Prolactinoma
The most common functioning pituitary tumor. Excess prolactin causes irregular periods and galactorrhea (unexpected breast milk) in women, and decreased testosterone and erectile dysfunction in men. Diagnosis: elevated serum prolactin, MRI showing pituitary adenoma. Treatment: dopamine agonists (cabergoline, bromocriptine) are highly effective â most patients achieve normalization of prolactin and tumor shrinkage without surgery.
Acromegaly â Excess Growth Hormone in Adults
Excess GH in adults causes acromegaly â characterized by enlargement of the hands, feet, and facial features; coarsening of skin; joint pain; excessive sweating; and increased risk of diabetes, hypertension, and cardiovascular disease. Diagnosis: elevated IGF-1, failure to suppress GH with glucose load, pituitary MRI. Treatment: surgical resection of the adenoma, then medications (octreotide/lanreotide, pegvisomant) or radiation if surgery is not curative.
Cushing's Disease
An ACTH-secreting pituitary adenoma causing excess cortisol production. Causes weight gain, hypertension, diabetes, osteoporosis, and emotional changes. Distinguished from other causes of Cushing's syndrome by pituitary MRI and inferior petrosal sinus sampling. Treatment: transsphenoidal surgical resection of the adenoma.
Hypopituitarism â Pituitary Hormone Deficiency
Multiple pituitary hormone deficiencies can occur from tumors, surgery, radiation, or injury. Each deficient hormone requires replacement: thyroid, adrenal, gonadal, and growth hormone deficiencies are all treatable. Pituitary apoplexy â sudden hemorrhage into a pituitary tumor â is a medical emergency requiring urgent treatment.
Diabetes Insipidus
Deficiency of ADH (vasopressin) causes diabetes insipidus â characterized by excretion of large volumes of dilute urine (polyuria) and intense thirst (polydipsia). It is unrelated to diabetes mellitus. Treatment: desmopressin (DDAVP) nasal spray or tablets.
Key Takeaways
- The pituitary "master gland" controls thyroid, adrenal, and gonadal function
- Pituitary adenomas are common and range from asymptomatic to causing significant hormonal excess
- Prolactinoma is the most common type â highly treatable with medication
- Acromegaly and Cushing's disease require prompt diagnosis and treatment to prevent complications
- An endocrinologist is essential for comprehensive pituitary disorder management