Adrenal Insuficiency and Addisons Disease

Tests

A patient presenting with non-specific symptoms, such as tiredness and nausea, will have a blood sample taken for a general biochemical and haematological screen plus some hormone tests.

Cortisol may be requested when Addison’s disease is suspected but this alone may be unhelpful. If the cortisol level is inappropriately low it suggests adrenal failure. Cortisol can then be measured as part of a stimulation tests to clarify the diagnosis.

ACTH (Adrenocorticotrophic Hormone) is often requested in Addison disease where levels of this hormone are usually high. In such patients a synacthen test should be carried out.

Synacthen is a drug which has the actions of ACTH , the hormone produced by the pituitary gland. Synacthen is given to stimulate the adrenal glands to produce cortisol.    A blood sample is taken to measure the unstimulated level of cortisol and sometimes aldosterone and plasma renin activity. Synacthen is then given.  After 30 minutes another blood sample is taken to see if cortisol and aldosterone have increased. A further sample at 60 minutes is sometimes also taken. In Addison’s disease cortisol and aldosterone levels do not increase.

Plasma renin is a substance in the blood that stimulates aldosterone release from the adrenal and will be high in patients with Addison’s disease.

Electrolytes (e.g. sodium, potassium) are routinely measured and a low sodium and high potassium level together with hypotension is suggestive of low adrenal function.

Glucose , urea and creatinine are measured to examine glucose levels and kidney function and, with the measurement of electrolytes, monitor the response to treatment.

Adrenal antibodies are sometimes requested as part of the diagnostic process when autoimmune Addison’s disease is suspected. A positive result is helpful in the diagnosis of autoimmune Addison's disease but many patients with this form of the disease have a negative result.

Non-laboratory tests

X-rays may be used to see if the adrenal glands have accumulated any calcium deposits that can occur with a tuberculosis infection.

CT (computerized tomography) or MRI (magnetic resonance imaging) scans, are used to look at the size and shape of the adrenal glands and the pituitary. The adrenal glands can be enlarged with infections and cancers. With autoimmune diseases the adrenal glands are often normal or small in size