Plasma catecholamine / metanephrine blood samples
What are plasma catecholamine / Metanephrine blood samples?
Blood samples will be taken from the arm using a small butterfly needle. Catecholamines / Metanephrines are a group of hormones (adrenaline, noradrenaline and dopamine) which circulate in the blood and help regulate blood pressure and heart rate. The levels of catecholamines/ Metanephrines in the blood changes with posture (the levels increase from lying to standing). Blood samples are usually taken whilst lying, following a 10 minute rest period, and whilst you are on the tilt table in the standing position.
On some occasions, a spot catecholamine/ Metanephrines blood sample is taken during testing. This usually occurs if the clinical autonomic scientist observes a sudden marked increase in blood pressure and / or heart rate which correlates to certain symptoms. This test is performed to determine whether there are any sudden increases in the catecholamine levels, which could explain the symptoms.
How do I prepare for the test?
Please do not eat for 4 hours prior to testing. You may drink water only in the lead up to the test. Please do not drink alcohol & do not carry out heavy exercise 12 hours prior to your appointment.
For the blood tests, please avoid the following food and drink items for 48 hours prior to testing: caffeine (coffee, tea, coca cola etc) bananas, chocolate, cocoa, citrus fruits & vanilla.
Please wear loose fitting clothing on the day of your appointment. We recommend a loose fitting T-shirt and loose fitting trousers or shorts.
If you require emla cream when having blood taken, you will need to obtain this from your GP or a doctor prior to your appointment. Emla cream needs to be prescribed by a doctor and we do not have a supply available in the unit / hospital. Please apply the emla cream to the antecubital fossa area on both arms 30 minutes prior to your appointment. Please refer to the red triangle below. Please bring extra emla cream to your appointment.
How will I feel during the test?
This is a very routine method for taking blood.
You may feel some brief discomfort as the needle is place in the arm. On occasions, some people experience dizziness and light headedness during the blood test(s). Please inform the clinical autonomic scientist if you experience these symptoms during testing.
What are the risks?
This is a very routine and minimally invasive test. But, as with any medical procedure, it does carry some risks. You may experience slight bruising at the site where the needle entered the skin. This should disappear within a few days.
Blood should not be taken from the same arm in which an arteriovenous fistula (such as used in hemodialysis) is present, or where lymphadema exists. Furthermore, caution should be used if you are at high risk for developing lymphedema (such as after lymph node dissection for treatment of breast cancer).
What happens if I have questions?
If you have any questions or concerns, please ask the clinical autonomic scientist before signing the consent form for the procedure. If you are not happy to proceed with the test, please inform a member of the testing team. Even after signing the consent form, you may withdraw your consent at any time during the test.
When will I get my results from the test?
We are unable to provide results of the test on the day of your appointment. All results will be sent to Professor Mathias. You will need to arrange a follow up appointment with Professor Mathias to discuss the results of the test(s). Please email firstname.lastname@example.org to arrange the appointment. Please note that the results of the blood test(s) can take 5 – 10 working days.