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Symptoms such as hyperpigmentation, weakness, low blood pressure, and salt cravings may cause a doctor to suspect adrenal insufficiency, especially if these symptoms appear to worsen during periods of stress. Laboratory tests are used to determine whether adrenal insufficiency is present, to distinguish between primary and secondary insufficiencies, and to try to determine the underlying cause of the condition. Tests are also ordered to evaluate a patient’s electrolyte balance, glucose level, and kidney function. During an Addisonian crisis, they are ordered to determine the severity of the imbalances (the glucose and sodium will often be low, the potassium high) and to monitor the effectiveness of treatment.

Laboratory tests
Cortisol. ACTH levels normally vary in the blood, peaking in the early morning. If the adrenal gland is either not functioning normally or not being stimulated by ACTH, then cortisol levels will be consistently low. Cortisol levels are used, along with ACTH and ACTH stimulation tests, to help diagnose adrenal insufficiency.

ACTH is a pituitary hormone that signals the adrenal glands to produce cortisol. This test is primarily ordered as a baseline test to evaluate whether or not the pituitary is producing appropriate amounts of ACTH. In a patient with adrenal insufficiency, low ACTH levels indicate secondary adrenal insufficiency, while high levels indicate primary adrenal insufficiency (Addison’s disease). The ACTH test is often ordered along with the ACTH stimulation test.

ACTH stimulation test. This test involves measuring the level of cortisol in a patient’s blood before and after an injection of synthetic ACTH. If the adrenal glands are functional, cortisol levels will rise in response to the ACTH stimulation. If they are damaged, then their response to ACTH will be minimal. 

Aldosterone. Blood or urine aldosterone levels are measured to help diagnose Addison’s disease - to determine whether the adrenal gland is producing aldosterone. If the levels are low, it is another indication that the patient may have a primary adrenal insufficiency.

Electrolytes (sodium, potassium, chloride and bicarbonate) are measured to help detect and evaluate the severity of an existing electrolyte imbalance, and to monitor the effectiveness of treatment. Electrolytes may be affected by many conditions; with Addison’s disease, the sodium, chloride, and bicarbonate levels are often low, while the potassium level may be very high.

Urea and creatinine are tests done to monitor kidney function.

Glucose levels may be very low during an Addisonian crisis. Glucose may be ordered help monitor a patient during a crisis.

Occasionally used tests
Insulin-induced hypoglycaemia test. Occasionally a doctor will order this test to assist in the detection of secondary adrenal insufficiency due to pituitary failure. Glucose and cortisol levels are measured at predetermined intervals after an injection of insulin is used to stress the pituitary glands. In healthy people, blood glucose levels fall and cortisol concentrations increase. In those with adrenal insufficiency, cortisol levels will remain low and glucose levels will fall then recover slowly.

Renin. Renin activity is elevated in primary adrenal insufficiency because a lack of aldosterone causes increased renal sodium losses. This lowers blood sodium levels and decreases the amount of fluid in the blood (which lowers blood volume and pressure), which in turn stimulates renin production.

Adrenal autoantibodies are sometimes ordered as part of the diagnostic process when autoimmune Addison’s disease is suspected. They are considered a good marker of autoimmune Addison's disease, but are not widely used at this time.

Non-laboratory tests
X-rays may be used to look for calcification on the adrenal cortex that may be due to a tuberculosis infection.

CT (computerised tomography) or MRI (magnetic resonance imaging) scans, are sometimes 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 and secondary adrenal insufficiency, the adrenal glands are often normal or small in size.

Last Review Date: July 1, 2018