Adrenal Disease Notes

Adrenal Disease

Mineralocorticoids e.g aldosterone

• Predominant effect is on extracellular balance of Na + K in distal tubule of kidney

• Secretion under control (mainly) of RAS

Glucocorticoids e.g cortisol (cross over with mineralocorticoids)

• Stimulate

  • Gluconeogenesis

  • Glycogen deposition

  • Proteolysis

  • Fat deposition

Axis

Hypothalamus CRH (corticotrophin releasing hormone)

Anterior Pituitary ACTH

Adrenal Gland Cortisol + weak androgens

Cushing’s Syndrome

= Clinical state of free increase in circulating glucocorticoid (cortisol)

Aetiology

1. ACTH-dependent causes (increased ACTH)

   1. Cushing’s Disease = pituitary adenoma secreting ACTH

      1. Adrenal hyperplasia

   2. Ectopic ACTH production = especially small cell lung ca + carcinoid tumours

   3. Rare ectopic CRH production from thyroid/prostate carcinoma or iatrogenic due to ACTH administration

2. ACTH – independent causes (reduced ACTH due to negative feedback)

   1. Iatrogenic = exogenous steroid administration

   2. Adrenal adenoma/carcinoma

   3. Adrenal nodular hyperplasia

Clinical features

• i.e those of glucocorticoid excess

Symptoms

• Weight gain

• Mood change

• Proximal weakness

• Gonadal dysfunction

  • Impotence

  • Irregular menses, hirsutism, acne

Investigations

• Overnight dexamethasone suppression test

  • 1mg dex at midnight

  • Serum cortisol before 9am next day

  • Normal patients = suppress cortisol, so cortisol < 50nmol/L

  • In Cushings there is failure to suppress cortisol secretion

• Or urinary 24hr free cortisol

• For localization

  • Plasma ACTH – if undetectable, adrenal tumour likely = CT scan

  • If detectable do high dose suppression test

    • Complete/partial suppression indicates cushing’s disease as pituitary retains some feedback control

    • Ectopic source not under feedback control

Management

• Depends on cause!

• Iatrogenic – stop meds.

• Cushing’s Disease

  • Selective removal of pituitary adenoma – transphenoid approach

  • Bilateral adrenalectomy if source cannot be located

• Adrenal adenoma – bilateral adrenalectomy

• Ectopic ACTH – surgery if tumour can be located

• Medical treatment with metyrapone/ketoconazole = decreased cortisol pre-surgery/awaiting radiotherapy to become effective

Complications

• Cardiovascular

Addison’s Disease (adrenal insufficiency)

Destruction of entire adrenal cortex therefore deficient in all steroids

Autoimmune destruction = commonest cause in UK

TB = commonest cause worldwide

Decreased cortisol = raised CRH, raised ACTH (via feedback)

Clinical features

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