Selenium
Note: this site is for informational purposes only. To view test results or book a test, use the NHS app in England or contact your GP.
A selenium test measures the amount of selenium, an essential trace element, in the blood using a blood sample taken from a vein in the arm. It is used to assess selenium deficiency or excess and to help investigate related conditions affecting nutrition, thyroid function or overall health.
Why get tested?
To measure the amount of selenium in the blood in order to identify/diagnose deficiency/toxicity or to monitor the response to supplementation
When to get tested?
When you have symptoms that may suggest selenium deficiency or toxicity. Following guidelines for the screening of malnutrition or if at risk of malnutrition.
Sample required?
A blood sample taken from a vein in your arm.
Test preparation needed?
None
Common questions
When a person has suspected selenium deficiency or toxicity. In particular selenium is measured in individuals receiving supplements, especially those who are receiving total parenteral nutrition (TPN) which is supplemented via the non-oral route.
Serum/plasma selenium concentrations can decrease during an acute illness or trauma. This does not necessarily infer selenium deficiency but may be a response to a redistribution of selenium (into tissues). Whole blood selenium measurements are not effected by acute illness and can be a more reliable marker. Serum/plasma selenium concentrations correspond to recent selenium intake whereas the measurement of whole blood selenium correlates with longer-term (roughly 2 months) selenium status.
Low selenium intake and deficiency has been associated with increased risk of cancer and cardiomyopathy. Supplementation may improve brain function in particular it is thought to improve mood, depression, anxiety and confusion.
Most individuals have an adequate supply of selenium in their diet and supplementation is not necessary. However, if you have any concerns please consult your GP who can review your dietary intake, investigate any symptoms and advise if testing is required.
Plasma selenium is a marker of immediate selenium status and varies daily depending upon dietary intake and any concurrent infections. Red cell selenium measures the selenium content inside red cells and gives an indication of total body selenium stores.