Addison’s disease

• Incidence
• Predisposing Factors
• Macroscopic Features
• Clinical History
• Clinical Examination
• General Investigation
• Specific Investigations
• Prognosis
• Treatment Overview
• References
• Drugs/Products Associated with Addison’s Disease

Incidence

About 1 in 100,000 people. It occurs in all age groups and affects men and women equally.

Predisposing Factors

• Autoimmune adrenalitis (60-70% of cases).
• Infections, particularly tuberculosis and fungal infections.

Macroscopic Features

The disease is characterised by weight loss, muscle weakness, fatigue, low blood pressure, and sometimes darkening of the skin (in both exposed and non-exposed parts of the body).

Clinical History

Chronic, worsening fatigue and muscle weakness, appetite loss, and weight loss are characteristic of the disease. Nausea, vomiting, and diarrhoea occur in about 50 per cent of cases. Blood pressure is low and falls further when standing, causing dizziness or fainting (postural hypotension).

Skin changes also are common in Addison’s disease, with areas of hyperpigmentation, or dark tanning, covering exposed and non-exposed parts of the body. This darkening of the skin is most visible on scars; skin folds; pressure points, such as the elbows, knees, knuckles, and toes; lips; and mucous membranes.

Addison’s disease can cause irritability and depression. Because of salt loss, craving of salty foods is also common. Hypoglycaemia, or low blood sugar, is more severe in children than in adults. In women, menstrual periods may become irregular or stop completely.

Symptoms of an Addisonian crisis include sudden penetrating pain in the lower back, abdomen, or legs; severe vomiting and diarrhoea, followed by dehydration; low blood pressure; and loss of consciousness. Left untreated, Addisonian crises can be fatal.

Clinical Examination

Patient may present with lethargy, depression, anorexia and weight loss. It may also present as an emergency (Addisionian crisis), with vomiting, abdominal pain, profound weakness and hypovolaemic shock. Postural hypotension caused by salt and water loss and hyperpigmentation are also important signs. There may be vitiligo and loss of body hair in women.

General Investigation

• Increased K+, Ca2+; Decreased Na+, glucose; Uraemia,
• ABGs: mild acidosis,
• Full blood count: eosinophilia, neutropenia, lymphocytosis, anaemia

Specific Investigations

In patients presenting with chronic illness, the following investigations should be performed before any treatment is commenced:

• Assessment of glucocorticoids with ACTH stimulation test.
• Assessment of mineralocorticoids with plasma electrolyte measurements, as well as plasma renin activity and aldosterone in the supine position.
• Other tests to establish cause.

In patients with suspected acute adrenal crisis, treatment should not be delayed pending results. A random blood sample may be stored for measurement of cortisol, and it may be appropriate to spend 30 minutes performing a short ACTH stimulation test; however, investigations may need to be performed after recovery.

Prognosis

Normal lifespan if treated.

Treatment Overview

Patients with adrenocortical insufficiency always need specific hormone replacement therapy. Replacement therapy should correct both glucocorticoid and mineralocorticoid deficiencies.

Hydrocortisone (cortisol) is the mainstay of treatment. The dose for most adults (depending on size) is 20-30mg/day. Patients are advised to take glucocorticoids with meals. To simulate the normal diurnal adrenal rhythm, two-thirds of the dose is taken in the morning, and the remaining one-third is taken in the late afternoon.

Mineralocorticoid supplementation is usually needed. This is accomplished by the administration of 0.05 to 0.1mg fludrocortisone per day by mouth. Patients should be advised to maintain an ample intake of sodium (3-4 g/day).

References

1. Adrenal insufficiency and Addison’s disease [online]. Bethesda, MD: National Institute of Diabetes and Digestive and Kidney Diseases; 2003 [cited 9 December 2003]. Available from: URL link
2. Ballinger A, Patchett S. Saunders’ Pocket Essentials of Clinical Medicine (2nd edition). London: WB Saunders; 2000. [Book]
3. Davidson S, Haslett C. Davidson’s Principles and Practice of Medicine (19th edition). Edinburgh: Churchill Livingstone; 2002. [Book]
4. Kumar P, Clark M (eds). Clinical Medicine (5th edition). Edinburgh: WB Saunders Company; 2002. [Book]
5. Longmore M, Wilkinson I, Torok E. Oxford Handbook of Clinical Medicine (5th edition). Oxford: Oxford University Press; 2001. [Book]
6. Cotran RS, Kumar V, Collins T, Robbins SL. Robbins Pathologic Basis of Disease (5th edition). Philadelphia: WB Saunders Company; 1995. [Book]

Drugs/Products Used in the Treatment of This Disease

• Florinef (Fludrocortisone acetate)