Catecholamines, Plasma and Urine

Other names: Adrenaline (Epinephrine); Free Urine Catecholamines; Dopamine; Noradrenaline (Norepinephrine)

Catecholamines are hormones, which are produced in the medulla region of the adrenal glands. The most common catecholamines include adrenaline, dopamine and noradrenaline; they are released into the bloodstream when the body is subjected to emotional or physical stress. The hormones help to stimulate nerve activity and encourage the release of glucose and fatty acids into the bloodstream, so that they can be used to generate energy. They also cause the pupils to dilate and the narrow air passages in the lungs to increase in size. Once the hormones have been used, they are broken down into inactive compounds.

Why is the test used?

The most common use of the test is to diagnose phaeochromocytomas (tumours which cause excessive amounts of adrenaline and noradrenaline to be produced). The test can also be used by doctors to monitor the efficacy of treatments in patients who have already been diagnosed with a tumour.

The test is usually ordered by doctors when a patient has symptoms of phaeochromocytomas; these include high blood pressure, headaches, rapid heart rate and excessive sweating. The test may also be used to monitor the condition of somebody who has a family history of phaeochromocytomas; it may also be ordered if a routine scan has discovered a tumour on the adrenal gland.

Doctors may also order the test when a patient has high blood pressure and their condition does not seem to be getting better with treatment.

How is the test performed?

In most cases, a 24 hour urine test is used for this test; however, a blood sample may also be tested. The sample is collected from a vein in the arm (usually on the inside of the elbow) and then bottled, labelled and sent away to the laboratory. It is important that you tell the nurse or doctor if you are taking any medication before you have the test. You may be asked to rest or lie down for a short period of time before the test is carried out.

What do the test results mean?

It is very common for the test to give a false positive result because the test is affected by many outside influences, including what the patient eats and drinks, their emotional state of mind, their general health and any medications they may be taking. Phaeochromocytomas are rare so the test often indicates high results, which are caused by other factors, rather than being symptomatic of a tumour. A doctor may order a number of tests when trying to diagnose a patient’s condition and they will consider the patient’s medical history, mental well-being, diet and lifestyle when evaluating their condition.

If levels of catecholamines are very high, this usually indicates a serious illness; however, it may also indicate that the individual is going through severe emotional stress and further tests will be required.

If levels of catecholamines are high in a patient who has previously been treated for phaeochromocytomas, this may indicate that the tumour has returned.

A number of different medications may affect the test results, so it is very important that the patient tells their doctor which medications they are taking before the test.

Specific Blood Tests

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