Selenium – laboratory test

Description

Why selenium is tested

Selenium is an essential trace element that forms part of about 25 proteins called selenoproteins. They take part in the metabolism of thyroid hormones, protect cells from oxidative damage, and support immunity and fertility. The thyroid contains more selenium than any other organ. Selenium has a narrow safety range: both deficiency and excess are harmful, which is why measuring the serum concentration is useful before and during supplementation. The serum concentration mainly reflects recent intake, not the body’s long-term stores.

When it is worth having this test

• before planned selenium supplementation and to monitor it, when recommended by a doctor,
• in people on parenteral nutrition or with malabsorption, e.g. after extensive bowel surgery,
• in people on long-term dialysis,
• if you have symptoms that may indicate excess selenium: hair loss, brittle or lost nails, garlic odour on the breath, a metallic taste,
• in the diagnosis of thyroid diseases, when the doctor wants to assess selenium status.

How to prepare

• Come in the morning, fasting: 8-12 hours after your last meal. You may drink still water.
• If you have recently had a test with a contrast agent containing gadolinium, iodine or barium, let us know: Mayo Clinic Laboratories recommends waiting 96 hours before the blood draw.
• Tell your doctor about all supplements containing selenium, including those in multivitamin products.
• Rest for about ten minutes before the blood draw.

How to read the result

The serum result mainly shows current selenium intake, and inflammation may affect some indicators of selenium status. A low result is not a diagnosis of any disease, and a high one calls for a review of the supplements you take with your doctor. The reference range printed on the laboratory report applies; it depends on age.

What to test together

TSH, FT4, Anti-TPO antibodies, Zinc, Iodine in urine, Copper in serum. More: Badania-Medyczne.pl.

Sources: ALAB laboratoria, Selenium (preparation, indications, turnaround time); NIH Office of Dietary Supplements, Selenium Fact Sheet for Health Professionals (role, assessing levels, deficiency, selenosis); Mayo Clinic Laboratories, Selenium, Serum (uses, interpretation, effect of contrast). For information only; it does not replace a medical consultation.