Hypopituitarism pathophysiology

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ahmed Elsaiey, MBBCH [2]

Pathophysiology

• The hormones of the anterior pituitary include 2 proteins, 3 glycoproteins and a polypeptide:
  • Prolactin (PRL) - stimulates milk production in the breast
  • Growth hormone (GH) - growth and glucose homeostasis
  • Luteinizing hormone (LH) - menstrual cycle and reproduction
  • Follicle stimulating hormone (FSH) - same
  • Thyroid stimulating hormone (TSH) - stimulates thyroxine production in the thyroid
  • Adrenocorticotropic hormone (ACTH) - stimulates glucocorticoid production in the adrenal gland

• These hormones excreted are secreted in individually characteristic pulsatile patterns, often with distinct circadian rhythm, rather than at steady rates throughout 24 hours.
• The posterior pituitary is the site of release of the nonapeptide hormones antidiuretic hormone (ADH) and oxytocin, the former regulating plasma osmolarity and the latter regulating uterine contractions during childbirth as well milk ejection from the breasts.
• Deficiency of a single pituitary hormone occurs less commonly than deficiency of more than one hormone. Sometimes referred to as progressive pituitary hormone deficiency or partial hypopituitarism, there is usually a predictable order of hormone loss.
• Generally, growth hormone is lost first, then luteinizing hormone deficiency follows. The loss of follicle-stimulating hormone, thyroid stimulating hormone, adrenocorticotopic hormones and prolactin typically follow much later. The progressive loss of pituitary hormone secretion is usually a slow process, which can occur over a period of months or years. Hypopituitarism does occasionally start suddenly with rapid onset of symptoms
• Most people with hypopituitarism lack growth hormone as well as one or more others. As for the posterior pituitary, antidiuretic hormone deficiency is the main problem, while oxytocin deficiency rarely causes clinically significant problems.