Written by Nabeel Salim
Last Reviewed: February 2019
Review Due: February 2020
'a clinical syndrome caused by an inadequate production of adrenal hormones'
Primary (Addison's Disease)
Autoimmune (most common cause in the UK)
Tuberculosis (most common worldwide)
Long Term Exogenous Steroid Use
SIGNS AND SYMPTOMS
Hyperpigmentation of Palmar Creases and Buccal Mucosa
Nausea and Vomiting
Diarrhoea and Constipation
In the UK, the leading cause of Addison's Disease (primary adrenal insufficiency) is autoimmune destruction of the adrenal cortex, resulting in impaired production of adrenocortical hormones, including cortisol and aldosterone. Worldwide, Adrenal TB is a more common cause of Addison's Disease.
Secondary adrenal insufficiencies are characterised by inadequate production of Adrenocorticotropic Hormone (ACTH) by the anterior pituitary. This can occur in patients on long term steroid therapy, where the adrenal axis becomes suppressed and fails to produce adequate levels of cortisol.
U&Es: Hyponatraemia, Hyperkalaemia and Uraemia
FBC: Eosinophilia, Anaemia
ACTH: High in Primary, Normal/Low in Secondary
Short Synacthen Test
This is the gold standard diagnostic test for Addison's Disease and involves measuring plasma cortisol levels before and 30 minutes after the administration of synthetic ACTH (250mcg IM). A normal response would see a large increase in cortisol levels at 30 minutes, however this would not be the case in patients with Addison's Disease
Patients with adrenal insufficiency require (usually lifelong) replacement therapy.
Glucocorticoid Replacement: Hydrocortisone
Mineralocorticoid Replacement: Fludrocortisone
Patients taking long-term steroids must be counselled on the risks associated with this. They may also require other medication, such as bisphosphonates for bone protection. Patients should also be advised to:
Carry identification indicating they take long-term steroids
Double their normal steroid dose in case of febrile illness or stress
Administer IM hydrocortisone if vomiting illness prevents oral intake
Never abruptly stop taking their steroids
Advise all their doctors/dentists/surgeons that they take regular steroids
Acute Adrenal Crisis
All patients presenting with an acute crisis (also known as an Addisonian Crisis) should have bloods taken for ACTH and cortisol. They should receive IV fluid resuscitation (to correct volume depletion), IV dextrose (to correct hypoglycaemia) and steroid replacement (to correct the lack of circulating glucocorticoid)
Addison's Disease is rare, with an approximate incidence of 0.6 per 100,000 and a prevalence of 4-11 per 100,000.