Autoimmune destruction of the adrenal glands is the most common cause of primary hypoadrenalism in the UK, accounting for 80% of cases. This is termed Addison's disease and results in reduced cortisol and aldosterone being produced.

Features

• lethargy, weakness, anorexia, nausea & vomiting, weight loss, 'salt-craving'
• hyperpigmentation (especially palmar creases)
  • ACTH is derived from a larger precursor molecule called proopiomelanocortin (POMC). When POMC is cleaved to produce ACTH, other melanocyte-stimulating hormones (MSH) are also produced. These MSHs have the effect of stimulating melanocytes in the skin to produce more melanin, the pigment responsible for skin colour
  • primary Addison's is associated with hyperpigmentation whereas secondary adrenal insufficiency is not
• vitiligo
• loss of pubic hair in women
• hypotension
• hypoglycaemia
• hyponatraemia and hyperkalaemia may be seen
• crisis: collapse, shock, pyrexia

Other causes of hypoadrenalism

Primary causes

• tuberculosis
• metastases (e.g. bronchial carcinoma)
• meningococcal septicaemia (Waterhouse-Friderichsen syndrome)
• HIV
• antiphospholipid syndrome

Secondary causes

• pituitary disorders (e.g. tumours, irradiation, infiltration)

Exogenous glucocorticoid therapy