Cortisol

Cortisol – What is this test?

A cortisol test is performed when the doctor suspects insufficient or excessive production of this hormone. Cortisol levels in the serum usually fluctuate – the highest levels are usually observed in the morning and evening, while they decrease throughout the day. This is why it is so important to perform the cortisol test at a specific time and interpret the results strictly based on the time of the test. The diagnosis of cortisol levels uses serum taken from the antecubital vein.

When to test cortisol? Indications

A cortisol level test should be performed if Cushing's syndrome is suspected (i.e., hyperactivity of the adrenal cortex and excessive cortisol production). The characteristic symptoms of this condition include:

• a specific appearance resulting from fat deposits around the face (called "moon face"), neck (known as "buffalo hump"), and torso.

• muscle wasting,

• thinner and more sensitive skin,

• high blood pressure,

• headaches and dizziness,

• insomnia,

• mood swings, depression,

• increased thirst,

• frequent urination,

• increased appetite,

• decreased libido,

Sometimes the test is done to rule out Addison's disease (cortisol deficiency). Cortisol testing should also be done to monitor the progress of treatment, particularly in people with adrenal insufficiency or Cushing's syndrome.

How to prepare for the test?

A cortisol test requires no special preparation. However, to obtain reliable results, the test should be done in the morning (usually between 7 and 9 a.m.). It is also essential to inform the doctor about any medications being taken, especially those that may affect cortisol levels, such as steroids, birth control pills, or other hormones.

When to test cortisol? On the day of the test, the following guidelines should be followed: 

• The patient should fast, meaning they should refrain from eating for about 8-12 hours before the test. 

• A small amount of water is allowed in the morning hours. 

• Whenever possible, cortisol testing in blood should be done before taking the morning dose of medication, unless the doctor advises otherwise. 

• Blood collection should be done in the morning hours. 

• Before the test, the patient should rest for 10–15 minutes (sitting position). 

• Physical activity, including moderate activities like walking or climbing stairs, can alter the laboratory test results. 

Stress hormone – how is the test performed? 

• The test involves blood collection into an EDTA tube, following a procedure that includes skin disinfection, applying a tourniquet, and pressure at the collection site after the procedure, which should last a few minutes. 

• Cortisol testing from blood takes about a few to several seconds. 

• If the test preparation is incorrect, the obtained result will not be fully reliable. 

• The sample must be taken in the morning hours. 

Cortisol test results 

A key factor in ensuring reliable cortisol test results is knowing the reference values. Normal cortisol levels are 166–507 nmol/l (morning) and 73.8–291 nmol/l (evening). If the cortisol test shows a lower value, it may indicate Addison's disease, and if higher, it may suggest Cushing's syndrome. 

Cortisol test – cost 

The cost of a cortisol test from serum starts from about 45 PLN.

How to check stress hormone?

A cortisol test from serum is needed.

How to measure cortisol levels?

The test involves drawing blood from the elbow vein. It is performed in the morning, on an empty stomach.

How much does the cortisol test cost?

Prices start from 45 PLN.

What is a cortisol test?

It is a blood test for cortisol levels, which is useful in diagnosing Cushing's syndrome (which can be indicated by increased cortisol levels) or Addison's disease (characterized by low cortisol levels).