Vitamins & Nutrients Updated Apr 17, 2026

Selenium (Se)

Selenium (Se) is a trace element measured in blood that helps describe nutrient status and how much selenium is circulating at the time of the test. Selenium on a lab report or selenium on a blood test is usually interpreted with the Selenium reference range, the testing method, and related vitamins and minerals.

What Is Selenium (Se)?

Selenium (Se) is a trace element measured in blood and reported as part of a Vitamins & Nutrients panel. Selenium on a lab report reflects the amount of Se circulating in the sample at the time of collection, not a long-term body store. It is one of the values people may review when looking at Se on a blood test or a broader nutrient panel. The result helps describe blood composition in terms of trace mineral status.

Why Is Selenium (Se) Tested?

Se is often ordered in a Vitamins & Nutrients panel, and it may also appear in broader nutrition-focused testing. A Se test helps show whether the measured amount is within the Selenium normal range for the lab method used. Selenium on a lab report is usually interpreted alongside other nutrient markers so the pattern can be viewed as a group. In routine settings, the Se test is used as a reference value rather than a stand-alone number.

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Selenium (Se) Normal Range

Group Range Unit
Adult Male 70–150 µg/L
Adult Female 70–150 µg/L

Reference ranges may vary by laboratory and individual factors.

What Does High Se Mean?

A high Se result means the measured selenium concentration is above the lab's Selenium reference range. In many US labs, values above the upper limit, often around 140 to 150 µg/L, are considered high Se. This usually reflects a greater amount of circulating Se in blood, which can come from recent intake, supplements, or concentration changes in the sample. A Se test result that is high Se is best read with the rest of the nutrient panel.

Associated factors

Recent supplement use — added intake can raise circulating Se and push a Se test result above the usual Selenium normal range.
High dietary intake — frequent intake of selenium-rich foods can increase the measured Se level.
Dehydration — reduced plasma volume can concentrate blood components and make Se appear higher.
Smoking — tobacco exposure is associated with higher measured Se in some studies.
Recent exercise — short-term shifts in plasma volume can temporarily concentrate a Se on a blood test.
Use of multivitamins or fortified products — these can add selenium and contribute to high Se.
Lab method differences — different assay methods may report slightly different Se values.
Natural variation by sex — small differences in baseline Se can occur between men and women.
Residence at higher altitude — plasma volume shifts can affect concentration-based Se results.

What Does Low Se Mean?

A low Se result means the measured selenium concentration is below the lab's Selenium reference range. In many US labs, values below the lower limit, often around 70 to 90 µg/L, are considered low Se. This usually reflects a smaller amount of circulating Se in the sample, which can happen when intake is low or when the blood sample is diluted. A Se test result that is low Se is read together with the full nutrient pattern and the reporting units.

Associated factors

Low dietary intake — not getting enough selenium from food can lower the measured Se value.
Poor absorption of nutrients — reduced uptake from the gut can lead to low Se.
Recent large fluid intake — dilution of blood can make Se appear lower on a blood test.
Long periods of limited food intake — lower intake over time can reduce circulating Se.
Digestive losses — ongoing loss of nutrients can lower Se levels.
Higher plasma volume states — expanded fluid volume can dilute concentration-based Se results.
Lab sample handling differences — pre-analytic variation can influence a Se test result.
Natural variation by age — baseline Se can differ slightly across age groups.
Pregnancy-related blood volume expansion — increased plasma volume can lower measured Se concentration.

How Selenium (Se) Relates to Other Values

Se is commonly read with other nutrient and blood markers from the same panel. In a Vitamins & Nutrients panel, the Se result may be reviewed alongside vitamin B12, folate, ferritin, and iron to describe whether several circulating nutrients are in range. When Se is compared with red cell markers such as hematocrit (Hct), red blood cell count (RBC), and mean corpuscular volume (MCV), the combination gives a broader picture of blood composition. Selenium on a lab report is therefore most useful as part of a pattern, not as a single number by itself.

What Factors Affect Selenium (Se) Levels?

Age, sex, hydration, and recent diet can all affect a Se test result. Time of day and recent exercise may also change blood concentration slightly through fluid shifts. Pregnancy can lower measured Se because plasma volume increases. Different laboratories may use different methods, so the Selenium normal range can vary between sites. Ethnic background and geography may also influence typical intake patterns and the baseline Se level in a population.

How It Is Tested

The Se test is done on a blood sample, usually from a vein in the arm. The laboratory measures selenium concentration and reports it in micrograms per liter (µg/L) or sometimes micrograms per deciliter (µg/dL), depending on the method. Selenium on a blood test is a concentration measurement, so it can shift with hydration and sample handling.

How to Prepare

No fasting is usually required for a Se test unless the same blood draw includes other tests that need fasting. Selenium on a lab report is usually interpreted using the lab's own reference interval and collection method.

Frequently Asked Questions

What is the normal range for Selenium?
The Selenium normal range is usually about 70 to 150 µg/L for adults, but the exact interval depends on the lab method. A Se result within that range is generally considered in-range for the specific Selenium reference range used by the laboratory.
What does Se stand for?
Se stands for selenium. On a lab report, Se is the abbreviation used for the trace element measured in the blood sample.
What does a high Selenium mean on a lab report?
A high Selenium result means the measured Se concentration is above the lab's reference range. In many reports, high Se reflects higher circulating selenium from recent intake, supplements, or sample concentration changes.
What does a low Selenium mean on a lab report?
A low Selenium result means the measured Se concentration is below the lab's reference range. Low Se often reflects lower intake, dilution of the blood sample, or reduced absorption of nutrients.
Can hydration affect Selenium?
Yes. Hydration can affect Selenium on a blood test because Se is reported as a concentration. More fluid in the bloodstream can make the result look lower, while less fluid can make it look higher.
What is the difference between Selenium and ferritin?
Se measures a trace element in blood, while ferritin reflects iron storage in the body. They are different markers, but both may appear on a nutrient-focused panel and can be read together with RBC, Hct, and MCV.
What unit is Selenium measured in?
Se is commonly measured in micrograms per liter, written as µg/L. Some laboratories may report Selenium in micrograms per deciliter, so the unit should always be checked with the result.
How much can Selenium change between tests?
Se can change modestly between tests because it is a concentration-based measurement. Hydration, recent diet, supplements, and lab method differences can all shift a Selenium test result.
Is Selenium different for men and women?
The Selenium normal range is often the same for adult men and adult women, such as 70 to 150 µg/L. Small population differences can exist, but many labs use one adult reference range for both sexes.
Why is Selenium tested in a Vitamins & Nutrients panel?
Selenium is included in a Vitamins & Nutrients panel to describe trace mineral status alongside other nutrient markers. The Se test helps show whether the blood sample is within the Selenium normal range and how it fits with the rest of the panel.
What does Se mean on a blood test?
Se on a blood test means selenium, the trace element being measured in the sample. The result is a concentration value that is compared with the lab's normal Selenium range.

Disclaimer

This content is for informational and educational purposes only. It is not intended as medical advice, diagnosis, or treatment recommendation. Reference ranges may vary by laboratory. Always discuss your results with a qualified healthcare professional.

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