Addison’s disease, also known as primary adrenal insufficiency, is diagnosed through a combination of symptoms, physical signs, and blood tests. In this article, we will explore the most common methods and explain how they work.
First, a doctor will review the individual’s medical history, and the patient will be asked whether there are any close relatives with autoimmune disorders.
The doctor will be interested in what symptoms are present, when they began, and how they affect everyday life. The doctor will carry out a physical examination, looking out for certain signs, such as low blood pressure or brownish discoloration of the skin (hyperpigmentation).
There are several tests that can assist in the diagnosis of Addison’s disease.
The first step in diagnosis is suspecting the disease based on signs and symptoms. These include:
- Symptoms – such as fatigue or weakness, nausea and vomiting, abdominal pain, constipation or diarrhea, dizziness, muscle pain or joint pain.
- Low blood pressure – this will be taken, usually while the patient is sitting, and then again shortly after standing up.
- Abnormal blood tests – such as low sodium (hyponatremia), low glucose (hypoglycemia) or high potassium (hyperkalemia).
- Urine test – this will show whether levels of cortisol are low.
After these tests, more specifics tests will be performed. These may include:
- cortisol levels in the urine
- morning cortisol level in the blood
- cortisol level in the saliva
- aldosterone levels in the blood
- adrenocorticotrophic hormone (ACTH) levels in the blood
In individuals with Addison’s disease, the cortisol level will be below the reference range and the ACTH will be elevated above the normal range.
Further testing may follow to check for other reasons why these hormones might be out of balance.
Computed tomography (CT) scan
The CT scanner uses radiation to produce images of the inside of the body. These images can be viewed in slices from different angles, giving the doctor a better idea of how the internal organs look. Some facilities can combine these CT images to form a 3-D image.
It is a painless procedure. The doctor may wish to scan the abdomen to check the size of the adrenal glands and determine whether any other abnormalities are present. The pituitary gland might also be investigated; this is because problems in the pituitary gland can have a knock on effect that causes secondary adrenal insufficiency.
ACTH stimulation test
This will be done if cortisol levels are low, or symptoms alone strongly suggest Addison’s disease. This test is usually done in an endocrinology unit.
Cosyntropin is a synthetic version of adrenocorticotrophic hormone (ACTH). It may be referred to by its trade names, such as Cortrosyn or Synacthen.
ACTH is produced by the pituitary gland to encourage the adrenal glands to secrete cortisol and aldosterone. When given synacthen, the patient’s adrenal glands should release cortisol and aldosterone into the blood.
The patient has several blood tests – one before the administration of cosyntropin and another 30-60 minutes later to check how the body responds. Blood may be drawn at multiple intervals. The blood levels of cortisol, aldosterone, and ACTH are measured. If ACTH levels are high, and cortisol and aldosterone levels are low, the doctor can then diagnose Addison’s disease.
An Addisonian crisis, also called an adrenal crisis or acute adrenal insufficiency, occurs when symptoms are severe. These symptoms can be life-threatening and lead to death, so the patient is treated immediately. Blood tests will be done and signs investigated in the same way, but the patient will receive treatment before the results are back.
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