How do I know if I am deficient in selenium?

Is there a blood test for selenium?

You can test whether you are low on selenium by checking your blood or saliva.

Many nutritional tests are done this way; the method is a variant of an enzymatic test, in that the chemical in the sample determines what happens when an enzyme with the presence of selenium and a substrate for it gets added.

However, not everyone gets an elevated result from these tests, because if you are genetically deficient in selenium (for example, you might be homozygous for a gene that codes for synthesis of Selenium-binding protein, see the SEPP1 gene) and have selenium intake too low to supply a baseline amount of functional selenoproteins to your system, then you would have a deficiency despite low selenium levels in your blood/saliva. Here are some links to papers on the test: Seppl, T. (1999). Selenotransferases - a new diagnostic opportunity in chronic diseases, such as rheumatoid arthritis and malignancy. Immunobiology and Clinical Immunology. 4(1): 1-8. )01001-9
Carpentier, F. X. Et al. (1999). The Selenoprotein P is increased in serum from patients with myelodysplastic syndrome and acute myeloid leukemia. J Acquir Immune Defic Syndr 16(3): 295-300.

Hofner, M. (2013). New perspectives in selenium status assessment by using total-body -glutamyl-Se-methyltransferase activity. Ann N Y Acad Sci 1306: 48-57.

How do I know if I am deficient in selenium?

Selenium deficiency is defined as an abnormally low amount of Se in the body.

To determine selenium status, serum levels of Se are considered the 'gold standard'. If the concentration is below 55 mcg/L, then deficiency is almost certainly present. For most people who don't follow a selenium rich diet (especially vegetarians), a concentration under 50mcg/L is fairly normal. If you fall into this group, you are probably not deficient, but it might be worth checking. Your diet and supplementation will have a great impact on your selenium status. If your serum concentration is above the deficiency limit, but you are having some health issues, such as hair loss or skin rashes, you may well be at risk of selenium deficiency. In those cases, it might be worth supplementing for some time until symptoms resolve. Selenium has been shown to prevent some cases of skin cancer, so if you are worried about this, talk to your doctor about whether supplementation is indicated for you. This article includes our recommendations for improving selenium status, including how to supplement effectively, but please also visit our selenium factsheet for more detailed information.

The most common sign of a selenium deficiency is hair loss, often starting at the front of the head. This is usually due to a lack of follicles, which can be a side effect of a number of illnesses (not just selenium deficiency). There are no known cures for hair loss, but one study found that patients with mild or moderate hair loss can expect to see a 40% recovery rate after 2 years with selenium supplementation. If you are deficient, supplementing may allow your hair to grow back more quickly.

Selenium deficiency can also lead to skin rashes. In other animals, selenium deficiency can cause the production of defective sperm, a condition called testicular degeneration. What about Se supplementation? Selenium is an essential mineral that cannot be made by the body. It is, however, plentiful in soil. Unfortunately, we have largely depleted this critical mineral. For example, 95% of selenium found in the UK is either mined or imported from abroad. The UK has only 2% of its selenium reserves, and it is estimated that these will be exhausted within 20-30 years.

How long does it take to correct a selenium deficiency?

In human subjects, the time is difficult to predict.

For those individuals who have suffered selenium deficiency for a few months before testing, the amount of selenium may be very low or even negative; thus taking a blood sample with this information would not be reliable. If a blood test confirms selenium deficiency, however, then supplementation could likely be completed in a couple of months. For those individuals who have had long-term selenium depletion (weeks or months), blood selenium could still be at acceptable levels, but oral supplementation could take much longer to reach optimal blood levels. The time it takes for adequate blood selenium levels to be reached will likely be determined by how severe the selenium deficiency was, and how well the person recovers after supplementation.

The above information is intended to help answer the question(s) of ? It depends on how much selenium deficiency there is. For example, if someone has been eating a diet high in selenium for decades but they just recently became ill, then the amount of selenium in their system would be lower than someone whose diet contains little selenium. If that person's blood selenium level had previously been 0 mcg/L or less and then rose into the 70-90 mcg/L range after supplementation, it would take several months for the body to repair. I have had a patient who took 20-30 mcg of selenium daily for 2 years and was never able to bring her blood selenium back above 50 mcg/L. Her physician wanted to put her on 100 mcg, but she wanted me to try to wean her off of it so she would not be over-supplemented. We used 20-30 mcg for over two years and her blood selenium went to 40 mcg/L, then to 50 mcg/L, then back to 40 mcg/L, etc., and she never had to go on more than 20 mcg daily. Now she has a blood selenium level of 98 mcg/L, so the body seems to have learned to control selenium better.