Adrenal gland disorders - adrenal insufficiency
Description
| Primary (Addison) | Secondary/tertiary | |
|---|---|---|
| Lesion | Adrenal cortex | Pituitary ACTH / hypothalamic CRH |
| ACTH | High | Low or inappropriately normal |
| Cortisol | Low | Low |
| Aldosterone | Low (renin high) | Normal - RAAS intact |
| Pigmentation | Yes (inc POMC) | No |
| K+ | High | Normal |
| Na+ | Low | Low (SIADH-like, from loss of cortisol's inhibition of ADH) |
| Adrenal androgens | Low | Low |
| Other axes | Intact | Often multiple deficits |
- *The electrolytes tell you which one*: hyperkalaemia = mineralocorticoid loss = primary
- Tertiary (exogenous glucocorticoid) is by far the commonest cause overall
Clinical
- Insidious: fatigue, anorexia, weight loss, nausea, vomiting, abdominal pain, myalgia, dizziness
- Postural hypotension, salt craving
- Hyperpigmentation - palmar creases, buccal mucosa, scars, pressure areas (primary only)
- Loss of axillary/pubic hair and libido in women (adrenal androgens)
- Bloods: hyponatraemia, hyperkalaemia, hypoglycaemia, mild normocytic anaemia, eosinophilia, lymphocytosis, mild hypercalcaemia
- Often diagnosed only in crisis, precipitated by an intercurrent illness
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