Share your insights

Help us by sharing what content you've recieved in your exams


Cushing’s syndrome

Learn the focussed examination too…

Cushing’s syndrome focussed examination covered here!

Cushing’s syndrome is a clinical syndrome characterised by the symptoms and signs that occur due to chronic glucocorticoid excess.

Hypothalamic–pituitary–adrenal axis

Terminology

  • Cushing’s syndrome = symptoms/signs resulting from chronic glucocorticoid excess
  • Cushing’s disease = ACTH-producing pituitary tumour causing Cushing’s syndrome

Causes

  • ACTH-dependent
    • Cushing’s disease (i.e. ACTH-secreting pituitary tumour)
    • Ectopic ACTH secretion (small cell lung cancer most common cause)
  • ACTH-independent
    • Iatrogenic (steroid treatment) – most common
    • Adrenal adenoma/carcinoma
    • Adrenal hyperplasia

Clinical features

  • Fat redistribution: weight increase, central obesity, cushingoid facial features (facial mooning), interscapular and supraclavicular fat pads
  • Skin: bruising, skin thinning, purple abdominal striae
  • Hyperpigmentation (ACTH-dependent causes)
  • Mood changes
  • Proximal myopathy

Investigations

Confirming Cushing’s syndrome

  • First-line tests – use one of:
    • Overnight dexamethasone suppression test (normally cortisol is suppressed by exogenous steroids, but not in Cushing’s syndrome)
    • 24-hour urinary cortisol 
  • Second-line tests (if needed)
    • 48-hour dexamethasone suppression test
    • Midnight cortisol

Localising causative lesion

  • Plasma ACTH
    • If ACTH is low: CT adrenals (look for adrenal tumour/hyperplasia)
    • If ACTH is high: high-dose dexamethasone suppression test (ACTH from a pituitary tumour is still suppressible at high exogenous steroid doses, whereas ectopic ACTH is not)
      1. ↘ if cortisol is not suppressed, CT thorax (look for ectopic ACTH source)
      2. ↘ if cortisol is suppressed, MRI pituitary – if tumour not seen, it may be too small to visualise and bilateral petrosal sinus sampling may be required to make diagnosis

Management

  • Metyrapone/ketoconazole to control symptoms if needed
  • Treat cause
    • Resect tumour (e.g. transsphenoidal adenomectomy in Cushing’s disease)
    • Bilateral adrenalectomy (if source cannot be localised/recurrent post-surgery/bilateral adrenal hyperplasia).

Try some questions

What are the possible complications of Cushing’s syndrome?

Oops! This section is restricted to members. Click here to signup!

What is Nelson’s syndrome?

Oops! This section is restricted to members. Click here to signup!

How do metyrapone and ketoconazole work in Cushing’s syndrome?

Oops! This section is restricted to members. Click here to signup!

Try a Cushing’s OSCE station

  1. Cushing’s disease focussed exam
  2. Find more stations here

Picture references

Cushing’s facial appearance: 2012. Ozlem Celik, Mutlu Niyazoglu, Hikmet Soylu and Pinar Kadioglu. Iatrogenic Cushing’s syndrome with inhaled steroid plus antidepressant drugs. Multidiscip Respir Med. 2012; 7(1): 26. Licenced under Creative Commons Attribution 2.0 Generic license (http://creativecommons.org/licenses/by/2.0). Sourced from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3436715/

No comments yet 😉

Leave a Reply