Inadequate production of one or more pituitary hormone as a result of damage to the pituitary gland and/or hypothalamus

Aetiology

• Pituitary tumours - nonfunctioning pituitary macroadenomas are the most common cause of hypopituitarism among adults
• Other local brain tumours - astrocytomas, meningiomas, gliomas, clival chordoma
• Iatrogenic - surgery or radiation
• Secondary metastatic lesions - lung, breast
• Traumatic brain injury
• Vascaular diseases - polyarteitis
• Subarachnoid haemorrhage
• Hypothalamic diseases - syphilis, meningitis
• Autoimmune - Sheenan (post pregnancy)
• Granulomatous inflammation - sarcoidosis, histiocytosis X tuberculosis, meningitis
• Infarction/haemorrhage

Pathophysiology

• Hypopituitarism becomes symptomatic when more than 80% of pituitary cells are damaged

Consequences of hypofunction

Anterior pituitary

• ↓ GH → growth failure
• ↓ TSH → secondary hypothyroidism
• ↓ LH/FSH → hypogonadism