Endocrine

Cushing's Syndrome

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Pathology

Cortisol excess from exogenous or endogenous source

Aetiology

Exogenous
Steroids: Usually iatrogenic 
Pseudo-Cushing’s: ETOH excess, depression
Endogenous
ACTH Dependant (ACTH)
Pituitary adenoma secreting ACTH (Cushing’s disease)
Ectopic ACTH secretion: e.g. small-cell lung cancer, carcinoid. 
Presents with hyperpigmentation, hypokalaemic alkalosis, weight loss
ACTH independent (ACTH)
Adrenal adenoma or carcinoma

Signs

Central obesity, easy bruising, proximal myopathy, thin shiny skin, painful purple striae, oedema, virilisation-excess hair, deep voice, coarse skin osteoporosis

Symptoms

Fluid retention, weight gain, tiredness, depression, headaches

Investigations

Bloods: FBC, U&E, LFTs, glucose, High or Low dexamethasone suppression test,
Urine: 24 hour urinary free cortisol
Imaging: Inferior petrosal sinus sampling (central: peripheral ACTH 4:1), 
Pituitary MRI, CT Chest, Abdomen and Pelvis

Treatment

Medical: Gradual weaning of exogenous steroids, treat hypertension or raised 
glucose, bone protection
Surgical: Removal of pituitary tumour, excision of ectopic source, bilateral 
adrenalectomy (ACTH dependant when source not identified). 

Prognosis

Good prognosis if cured but if poorly controlled complications of vascular disease and diabetes. Adrenal carcinoma has a poor prognosis
Relapse, osteoporosis, recurrent infections, metabolic complications, panhypopituitarism, Nelson’s syndrome (aggressive corticotroph tumour post bilateral adrenalectomy in pituitary Cushing’s), diabetes

Key Facts

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Key References

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