This leaflet is intended for patients who have been asked by their doctor or nurse to collect a 24 hour urine sample for metanephrines. If you are unsure whether your doctor has asked you to perform a 24 hour urine collection specifically for metanephrines measurement, please contact them for advice.
Please also read our “How to collect a 24 hour urine sample” for general information and collection instructions.
You should have been provided with the following items together with this leaflet:
- A five litre container labelled: ‘This urine collection bottle contains: Hydrochloric acid’
- plastic funnel (on request)
- green plastic carrier bag
- Collection instructions pamphlets
If the collection bottle does not state that it contains hydrochloric acid, please contact the clinic or GP practice which gave you the collection bottle as you will need an alternative one. The hydrochloric acid in the bottle acts as a preservative, please do not discard or rinse it out. Please note any warnings or instructions, which are printed on the outside of the container.
This preservative is toxic and corrosive. If any bodily contact occurs, immediately wash with plenty of free flowing water. If splashed in eyes, wash with water for at least 10 minutes and seek urgent medical advice.
Always store the container safely out of reach of children.
Background to your test
In a small proportion of patients, high blood pressure can be caused by a tumour called pheochromocytoma which produce excess catecholamines (adrenaline and noradrenaline). Metanephrines are inactive breakdown products of catecholamines. Measurement of these compounds can assist in determining the presence of a pheochromocytoma or a neuroendocrine tumour which may be producing these.
Certain medicines can interfere with the laboratory measurements of metanephrines. For this reason you may have been asked by your doctor to stop taking some of your medications before and during the collection. It is also important that you inform your doctor about the all prescription and over-the–counter medications you may be taking during / before the collection as otherwise your results may be misleading and lead to further avoidable tests.
Please do not stop taking your medication unless instructed to do so by your doctor.
It is advisable to avoid coffee and tea during the collection period.
It is also recommended that you minimise vigorous exercise and emotional / physical stresses prior to and during sample collection as they can increase catecholamine secretion.
This information has been produced by:
Department of Clinical Biochemistry and Immunology
Cambridge University Hospitals NHS Foundation Trust
Box 232, Hills Road, Cambridge, CB2 0QQ
We welcome any comments relating to the information you have received and may be contacted on the above address or through duty biochemist by telephone on 0333 103 2220 or email.
We are smoke-free
Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.
Help accessing this information in other formats is available. To find out more about the services we provide, please visit our patient information help page (see link below) or telephone 01223 256998. www.cuh.nhs.uk/contact-us/accessible-information/
Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge
Telephone +44 (0)1223 245151