Cushing’s syndrome
How cortisol normally helps the body handle stress, why long-term steroid medicines or tumours of the pituitary or adrenal glands produce too much, and how excess cortisol reshapes fat, muscle, skin, bone, blood sugar and blood pressure.
By the end, you can
- Describe the hypothalamic-pituitary-adrenal axis and the main actions of cortisol.
- Classify causes as exogenous, ACTH-dependent or ACTH-independent and predict their ACTH levels.
- Relate central obesity, thin skin, striae, bruising and muscle weakness to cortisol’s actions.
- Explain why excess cortisol causes high blood glucose, high blood pressure, infections and osteoporosis.
- Explain the logic of screening tests that look for loss of normal cortisol control.
- Recognise the classic morphology, key numbers and localising tests of Cushing’s syndrome, and explain how surgery and the main drug classes act on its mechanism.
What it is
Cushing’s syndrome is the clinical result of prolonged exposure to too much glucocorticoid (cortisol or a similar steroid). The commonest cause is steroid medication. Among endogenous causes, a pituitary adenoma secreting ACTH, called Cushing’s disease, is the most frequent; others are adrenal tumours and ACTH made by tumours elsewhere.
3 types to tell apart
- Exogenous
- Long-term glucocorticoid medicines such as prednisolone; the commonest cause overall.
- ACTH-dependent
- A pituitary adenoma (Cushing’s disease) or ectopic ACTH from a tumour, often in the lung; both adrenals are overstimulated.
- ACTH-independent
- An adrenal adenoma or carcinoma makes cortisol on its own; ACTH is suppressed.
US spelling: tumours → tumors, adrenaline → epinephrine.
Normal function
Cortisol and its daily rhythm
CRH from the hypothalamus prompts the to release ACTH, which drives the adrenal cortex to make cortisol. Cortisol feeds back to slow CRH and ACTH. Levels follow a daily rhythm: highest on waking, lowest around midnight, and they surge with physical stress.
Cortisol raises blood glucose by stimulating glucose production in the liver and reducing glucose uptake by muscle and fat; it breaks down muscle protein and releases fatty acids to fuel this. It helps maintain blood pressure by making vessels more responsive to adrenaline.
It also damps inflammation and immune responses and affects mood, bone and connective tissue. In short bursts these effects help us survive stress; prolonged excess causes harm.
Underlying change · Step 1 of 4
Where the excess comes from
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
Fat moves, muscle and skin thin
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
High glucose, high blood pressure, weak defences
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
Finding lost control
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 .