Selenium Blood Test Profile: Preparation, Timing & What to

At a glance

Selenium Blood Test Profile: prep snapshot

Sample type: Blood draw
Fasting: Fasting is often not required for this test, but requirements depend on the lab and on whether…
Best collection time: A blood sample can generally be collected at any time of day that fits your schedule and the…
Typical turnaround: Varies by collection lab
Category: General Wellness

This page explains how to prepare for a Selenium Blood Test, what the test measures, and what to confirm with the collection lab. The selenium blood test measures the amount of selenium in your blood.

What this test looks at

The test measures the concentration of selenium circulating in your blood. Results are interpreted against a reference interval to see whether your level is low, typical, or elevated. Your clinician uses that value along with your history, diet, supplements, and workplace exposure to interpret the result.

Selenium concentration
Exposure level
Deficiency status

Selenium Blood Test prep, step by step

Standard preparation covers most blood tests, so no special routine is usually required. Check with the testing location about any timing or fasting instructions before your visit.

Confirm with the collection lab whether you need to fast and for how long.
Tell the lab about any selenium supplements, multivitamins, or protein shakes you take, since these can raise your level.
Describe any occupational or environmental exposure to selenium so it can be noted on the order.
Drink water normally before your appointment to make the blood draw easier, unless told otherwise.
Bring your test order and photo identification to the collection site.
Ask the lab whether any of your medications should be timed around the draw.

Fasting, timing, sample type, and what to bring

Fasting

Fasting is often not required for this test, but requirements depend on the lab and on whether other tests are drawn at the same time. Follow the instructions on your order and confirm with your lab.

Best time to collect

A blood sample can generally be collected at any time of day that fits your schedule and the lab's hours. If your clinician wants to compare results over time, try to collect samples at a similar time of day on each occasion and confirm the preferred window with your lab.

Sample type

Blood draw. The collector will explain the process before starting.

What to bring

Your printed lab order or requisition form — the ordering physician prepares it for you after you order, and you print it (or fax it from your account) before visiting
Your order confirmation email, in case the collection site asks to see it
A written list of the medications and supplements you currently take
A short-sleeved or loose-sleeved shirt for an easy blood draw
Water to drink before the draw and a light snack for afterward, if your test requires fasting
A government-issued photo ID (most collection sites verify identity at check-in)

You do not need an insurance card or a payment method at the collection site: the lab does not bill insurance, and you pay at order time, so there is no copay or deductible. The lab also provides the physician's requisition, so you do not need a separate doctor's referral.

Order process and what-to-bring details reflect the lab's published instructions, paraphrased in our own words. Confirm final requirements with the collection lab that will perform your draw.

At the collection site

A phlebotomist cleans the skin, usually on the inside of your elbow, and inserts a small needle into a vein to collect a tube of blood. The draw takes only a few minutes, and you can usually return to your normal routine right away.

Details worth confirming with the collection lab before your visit:

Do I need to fast before this test, and for how long?
Should I pause any selenium supplements or vitamins before the draw?
When and how will my results be released to me?

When this test is useful

A clinician may order this test to monitor people who work with or are exposed to selenium in industrial settings. It may also be ordered when a selenium deficiency is suspected because of diet, absorption problems, or certain medical treatments.

What results mean

Reference ranges for selenium can differ between laboratories because of the method and equipment used. Your report will show the range that applies to the lab that processed your sample, so always read your value against that specific range.

General test information is compiled from publicly available reference material, including MedlinePlus (medlineplus.gov) and the Centers for Disease Control and Prevention (cdc.gov), and is reviewed for clarity. Preparation and what-to-bring details reflect the lab's published instructions, paraphrased into our own words. Preparation instructions, timing, and pricing vary by collection lab — always confirm them with the lab that will perform your draw.

Common questions

Frequently asked questions

Do I need to fast for a selenium blood test?

Many labs do not require fasting for this test alone, but rules vary and can change if other tests are ordered at the same time. Confirm the fasting instructions with your collection lab before you arrive.

Will my selenium supplement affect the result?

Yes, selenium supplements and multivitamins can raise the measured level. Tell your clinician and the lab what you take so the result can be interpreted correctly and so you know whether to pause anything beforehand.

How long does it take to get results?

Results are typically available within one to three business days, though the exact timing depends on the laboratory and how the sample is shipped. Ask your collection site for their expected turnaround.

Can I eat or drink normally before the draw?

In most cases you can follow your normal routine unless your order says otherwise. Water is encouraged to help with the blood draw, and any food restrictions should come directly from your lab or clinician.

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