Biochemistry · Molecule
Cortisol !
The main glucocorticoid: it raises glucose, mobilises reserves in fasting and stress, and damps down inflammation.
Updated 2026-11-01
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Key facts
- The zona fasciculata makes it under ACTH control; it peaks on waking and dips around midnight.
- In blood it travels mainly bound to cortisol-binding globulin (transcortin) and albumin.
- It induces PEPCK and glucose 6-phosphatase (gluconeogenesis), breaks down muscle protein, helps lipolysis and is permissive for glucagon and catecholamines.
- It acts through the (nuclear) glucocorticoid receptor; in the kidney 11β-HSD2 inactivates it so it does not occupy the mineralocorticoid receptor.
- Also called
- Hydrocortisone
- Formula
- C21H30O5
- PubChem
- CID 5754
Structure
- A 21-carbon steroid with hydroxyl groups on carbons 11β, 17α and 21 and a ketone on carbons 3 and 20.
- The 11β-hydroxyl is essential: the enzyme 11β-HSD2 oxidises it to form cortisone, which is inactive.
Clinical notes
- Excess (Cushing syndrome): central obesity, purple striae, hyperglycaemia, hypertension, proximal muscle weakness and osteoporosis.
- Deficiency (adrenal insufficiency): fatigue, hypotension, hypoglycaemia and, in Addison disease, hyperpigmentation from high ACTH.
- Liquorice inhibits 11β-HSD2: cortisol activates the mineralocorticoid receptor and causes hypertension with hypokalaemia.
Pathways
Related conditions
- Cushing syndrome
- Adrenal insufficiency
- Congenital adrenal hyperplasia due to 21-hydroxylase deficiency
Related
- Adrenal enzymes and congenital adrenal hyperplasia
- 11β-Hydroxylase (CYP11B1)
- 21-Hydroxylase (CYP21A2)
- Steroid hormone synthesis (overview)
- Nuclear receptors
- Catecholamines: synthesis and breakdown
- Phosphoenolpyruvate carboxykinase (PEPCK)
- Fed, fasting and starvation states
- Cholesterol
Test yourself
Think of the answer, then tap the question to see it.
How does cortisol favour gluconeogenesis?
It induces PEPCK and glucose 6-phosphatase transcription and supplies amino acids by breaking down muscle protein.
Why does cortisol not normally act as a mineralocorticoid in the kidney?
Because 11β-HSD2 turns it into inactive cortisone before it binds the mineralocorticoid receptor.
At what time of day is cortisol highest?
On waking, early in the morning; the lowest value is around midnight.
Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Cortisol (CID 5754) (PubChem, NCBI, 2026) · Public domain; Cortisol blood test: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); NR3C1: Glucocorticoid receptor (human) (UniProt, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).
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