: Selenium [Mass concentration] in Serum or Plasma

: What Is Selenium?

: Selenium is a trace mineral that your body needs in small amounts. It is incorporated into proteins called selenoproteins, which act as antioxidants and help regulate thyroid hormone activity. You get selenium from foods such as Brazil nuts, seafood, meat, eggs, and grains.

: Why the Test Is Ordered

: A healthcare provider may order a selenium test if you have symptoms that could suggest a deficiency, such as fatigue, muscle weakness, or hair loss, or if you have a condition that affects nutrient absorption. It may also be checked if you are receiving nutrition through a vein (parenteral nutrition) or if overexposure is a concern.

: How the Sample Is Collected

: The test is usually done on a blood sample drawn from a vein in your arm. In most cases no special preparation is required, but your provider may give you specific instructions. Tell your provider about any supplements you take, because they can affect the result.

: Understanding Your Results

: Your result is compared with the laboratory's reference interval, which can vary between labs. A low level may point to inadequate intake or poor absorption, while a high level may reflect excessive supplementation or exposure. Results are interpreted alongside your symptoms, diet, and other tests, and are not a diagnosis on their own.