Adrenal insufficiency
How the adrenal cortex makes cortisol and aldosterone, why autoimmune damage, pituitary disease or stopping steroids leaves too little, and how the loss causes tiredness, low blood pressure, salt craving, darker skin and adrenal crisis.
By the end, you can
- Describe the zones of the adrenal cortex and the hormones each makes.
- Distinguish primary from secondary adrenal insufficiency and predict ACTH, aldosterone and skin changes in each.
- Explain low sodium, high potassium, low blood pressure and low glucose from hormone loss.
- Explain why primary adrenal insufficiency darkens the skin.
- Explain how illness can trigger an adrenal crisis and why steroids must not stop suddenly.
- Recognise the morphology of the main causes, the hormone patterns and the short Synacthen test, and explain how glucocorticoid and mineralocorticoid replacement and crisis treatment act on the mechanism.
What it is
Adrenal insufficiency is too little cortisol from the adrenal cortex, with or without too little aldosterone. In primary insufficiency (Addison’s disease) the adrenal glands themselves are damaged, most often by autoimmunity. In secondary insufficiency the pituitary makes too little ACTH, most commonly because long-term steroid medicines have suppressed it.
2 types to tell apart
- Primary (Addison’s disease)
- Adrenal cortex destroyed: autoimmune in most cases in high-income countries; tuberculosis worldwide. Cortisol and aldosterone both fall.
- Secondary
- Too little ACTH: suppression by long-term steroids, or pituitary tumours, surgery or radiotherapy. Aldosterone is largely preserved.
US spelling: centre → center, adrenaline → epinephrine.
Normal function
Three zones, three hormone families
Each sits on the upper pole of a kidney. Its outer cortex has three zones: the outer zona glomerulosa makes aldosterone, the middle zona fasciculata makes cortisol, and the inner zona reticularis makes adrenal androgens. The medulla in the centre makes adrenaline.
Cortisol is driven by pituitary ACTH. It keeps glucose available between meals, supports blood pressure by helping vessels respond to adrenaline, and rises sharply during illness, injury or surgery.
Aldosterone is driven mainly by the renin-angiotensin system and by potassium, not ACTH. It makes the kidney retain sodium (and with it water) and excrete potassium, maintaining blood volume.
| Feature | Hormone | Main control | Main action |
|---|---|---|---|
| Zona glomerulosa | Aldosterone | Renin-angiotensin, potassium | Kidney keeps sodium, loses potassium |
| Zona fasciculata | Cortisol | ACTH | Glucose, blood pressure, stress response |
| Zona reticularis | Adrenal androgens | ACTH | Body hair, libido (mainly in women) |
Underlying change · Step 1 of 4
Primary or secondary
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 2 of 4
Losing cortisol and aldosterone
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 4
Why the skin darkens
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 4 of 4
Adrenal crisis
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .