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Pea-sized 'master gland' below the brain that secretes hormones controlling growth, metabolism, and other glands.
Medically reviewed & updated
Often called the 'master gland,' the pituitary gland orchestrates much of the endocrine system by releasing hormones that direct other glands and regulate growth, metabolism, reproduction, and water balance. It works in tight partnership with the hypothalamus directly above it.
The pituitary is a pea-sized gland (roughly 8 mm front-to-back and 12 mm wide in adults) that sits in a bony pocket called the sella turcica within the sphenoid bone, at the base of the skull below the brain. It is divided into two functionally distinct parts: the anterior lobe (adenohypophysis) and the posterior lobe (neurohypophysis), with a small intermediate region between them. The anterior lobe is true glandular tissue, while the posterior lobe is composed of nerve tissue extending from the hypothalamus.
The anterior pituitary produces and secretes most pituitary hormones, under control of hypothalamic releasing factors delivered through a portal blood system. These include growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin. Several of these are 'tropic' hormones that command downstream glands such as the thyroid, adrenals, and gonads.
The posterior pituitary does not manufacture hormones itself. Instead, it stores and releases two hormones made in the hypothalamus: antidiuretic hormone (ADH/vasopressin), which conserves body water, and oxytocin, which drives uterine contractions and milk release.
Pituitary adenomas (usually benign tumors) are common and can either oversecrete hormones or compress nearby structures, including the optic chiasm, causing visual field loss. Excess growth hormone causes acromegaly in adults or gigantism in children, while excess prolactin can disrupt fertility and menstruation. Underactivity (hypopituitarism) can affect growth, thyroid, adrenal, and reproductive function. Damage to the posterior pituitary or its hypothalamic source causes diabetes insipidus.
*This content is educational and not a substitute for professional medical advice.*