Adrenal Insufficiency

Adrenal insufficiency is where there's a reduction in the production of adrenal hormones i.e. cortisol and aldosterone.

Classification

Primary - This is known as Addison’s Disease, and it leads to a deficiency in both cortisol and aldosterone. It's causes include:

• Autoimmune

• Surgical removal

• Trauma

• Infections esp. TB

• Waterhouse-friderichsen syndrome (adrenal blood vessel rupture secondary to severe bacterial infection)

Secondary - Loss of pituitary function, leading to inadequate ACTH, therefore a cortisol deficiency only. It's causes include:

• Iatrogenic

• Surgery

• Infection

• Sheehan’s syndrome (massive blood loss during childbirth leading to ischaemia and necrosis of the pituitary gland)

Tertiary - Loss of hypothalamic function, leading to inadequate CRH, therefore a cortisol deficiency only. It's caused by long-term steroid use (3+ weeks).

Presentation

• Hypotension

• Fatigue and weakness

• Weight loss

• Skin hyperpigmentation - ACTH stimulates the production of melanin

• Abdominal pain, nausea, altered bowel habits

N.B. ACTH is derived from a bigger precursor, called pro-opiomelanocortin (POMC). POMC is also a precursor for melanocyte stimulating hormone (MSH), therefore causing increased melanin production and hyperpigmentation.

Investigations

The main investigations to do include:

• Sodium - low

• Potassium - high

• Cortisol - low

• Aldosterone - low in primary, normal in secondary

• ACTH - high in primary, low in secondary

• CT adrenals if primary, MRI head if secondary

Diagnosis - Short Synacthen test

• No rise in cortisol if primary

• Rise in cortisol if secondary

N.B. Aldosterone keeps Na in and pushes K out.

Management

• Hydrocortisone (cortisol replacement)

• Fludrocortisone (aldosterone replacement)

  • Dose of these corticosteroids should be doubled if experiencing minor intercurrent stress e.g. illness

Addisonian Crisis

This is a state of severe addison’s with a life-threatening presentation. It presents with reduced consciousness, hypotension, hypoglycaemia, hyponatraemia, and hyperkalaemia.

Triggers - Infection, Trauma, Sudden cessation of long-term steroids

Management:

• Aggressive fluid resuscitation

• IV steroids

• Glucose if hypoglycaemic