Cushing's syndrome
Too much cortisol over a long time. Most often it is caused by steroid medication; when it arises inside the body it is usually a pituitary or adrenal tumour. It produces a recognisable picture of central weight gain, a round face, thin skin and high blood pressure.
What it is
Cushing's syndrome is the effect of chronically high cortisol, the body's main stress hormone. By far the commonest cause is exogenous — long-term glucocorticoid medication (tablets, injections, even potent creams or inhalers). Endogenous causes are rarer: a pituitary tumour making too much ACTH (Cushing's disease), an adrenal tumour making cortisol directly, or, uncommonly, an ACTH-secreting tumour elsewhere. Sustained cortisol excess redistributes fat to the trunk, face and upper back, thins the skin and muscle, weakens bone, raises blood sugar and blood pressure, and affects mood. Diagnosis is a two-step process: first confirm that cortisol really is excessive (it varies through the day), then find the source. It is uncommon but important because it is treatable and, untreated, carries serious cardiovascular and metabolic risk.
Key lab markers
- Cortisol — screening tests — late-night salivary cortisol, 24-hour urinary free cortisol, or an overnight 1 mg dexamethasone suppression test; a single random cortisol is not enough because it swings through the day.
- ACTH — separates pituitary/ectopic (ACTH high or normal) from adrenal (ACTH suppressed) causes.
- Potassium — can be low, especially in ectopic ACTH.
- Fasting glucose / HbA1c — often raised; steroid-induced diabetes.
- Lipids — frequently abnormal.
- Imaging (pituitary MRI, adrenal CT) — locates the source once biochemistry confirms it.
Symptoms
- Weight gain concentrated on the trunk, with a rounded 'moon' face and a fat pad at the upper back
- Thin, easily bruised skin; wide purple stretch marks (striae)
- Muscle weakness, especially thighs and shoulders
- High blood pressure, new or worsening diabetes
- Mood changes, anxiety, low mood, poor sleep
- Acne, excess facial hair, irregular periods in women
- Fragility fractures from bone loss
- Slow wound healing, frequent infections
Related lab panels
When to discuss with a doctor
The single most important step is to review long-term steroid medication, which explains most cases and should never be stopped abruptly. When Cushing's is suspected without steroid use — the combination of central weight gain, purple striae, easy bruising, muscle weakness, new diabetes and hypertension — dedicated cortisol testing (not a random level) is needed, followed by ACTH and imaging to find the source. Confirmed endogenous Cushing's is managed by endocrinology, usually with surgery to remove the responsible tumour. Because the metabolic and cardiovascular risks are real, it should not be left to drift. Mediora.AI can flag the glucose, potassium and, where available, cortisol pattern; the diagnostic pathway belongs with endocrinology.