Selenium (Red Cell)
The Selenium (Red Cell) test measures long-term selenium status within red blood cells. It provides a more accurate reflection of selenium levels than serum testing.
Turnaround time
1 day
Biomarkers count
1
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Details about Selenium (Red Cell)
What is the Selenium (Red Cell) test?
The Selenium (Red Cell) test is a blood test that measures selenium concentration within red blood cells rather than in serum. Because red blood cells reflect mineral uptake over their lifespan, this test provides a longer-term and more stable assessment of selenium status.
Selenium is an essential trace element involved in antioxidant defence, immune function, thyroid hormone metabolism, and cellular protection. Red cell testing is particularly useful when assessing chronic deficiency or monitoring nutritional optimisation.
Clinically, this test is preferred over serum selenium when a more accurate picture of tissue selenium levels is required.
Why do I need a Selenium (Red Cell) test?
Selenium deficiency can develop due to poor dietary intake, restrictive diets, digestive or absorption disorders, or long-term illness. UK soil selenium levels are relatively low, making deficiency more common than many people realise.
Because short-term dietary intake can affect serum levels, red cell testing helps avoid misleading results. This test is especially useful when investigating fatigue, immune weakness, thyroid issues, or chronic inflammation.
You may benefit from this test if you experience:
- Frequent infections or poor immune response
- Fatigue or low energy
- Thyroid dysfunction or unexplained thyroid symptoms
- Muscle weakness
- Poor recovery from illness
- Restrictive or plant-based diets
- Long-term digestive or absorption issues
Benefits of the Selenium (Red Cell) test
- Assesses long-term selenium status
Reflects tissue selenium levels rather than short-term intake. - More accurate than serum selenium
Less affected by recent diet or supplementation. - Supports immune health assessment
Selenium is essential for immune cell function. - Supports thyroid function evaluation
Required for normal thyroid hormone metabolism. - Assesses antioxidant defence
Selenium is a key component of antioxidant enzymes. - Useful in chronic symptoms
Relevant for fatigue and inflammatory conditions. - Guides targeted supplementation
Helps avoid unnecessary or excessive selenium intake. - Supports preventative health strategies
Useful for long-term nutritional optimisation.
Step-by-step – How we offer this test
Option 1: Clinic-based blood test (UK-wide)
- Choose your nearest UK clinic
- Attend your appointment
- A clinician draws a blood sample
- Sample analysed for red cell selenium
Option 2: Home or hotel visit (+£60, UK-wide)
- A qualified phlebotomist comes to your location
- Blood sample taken at home or in your hotel
- No travel required
- Same laboratory processing and reporting
Your results explained
Low Red Cell Selenium levels
Low levels indicate selenium deficiency, suggesting inadequate long-term intake or poor absorption.
Typical UK interpretation (low):
- Below laboratory reference range
Low selenium may affect immune defence, thyroid hormone metabolism, and antioxidant capacity.
Normal Red Cell Selenium levels
Normal levels suggest adequate long-term selenium status to support immune, thyroid, and antioxidant functions.
Typical UK interpretation (normal):
- Within laboratory reference range
No action is usually required unless symptoms persist.
High Red Cell Selenium levels
High levels are uncommon and usually related to supplementation.
Typical UK interpretation (high):
- Above laboratory reference range
Persistently high levels may increase toxicity risk and should be reviewed.
How It Works
Simple steps to get your results
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Visit or Test at Home
Attend one of our UK or London clinics, arrange a home nurse visit, or use a finger-prick kit where available.
Get Your Results
Your sample is analysed by accredited UK laboratories, with secure results delivered directly to you.
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WhatsApp UsHow to Prepare for Your Test
Follow these guidelines for accurate results
Sample Timing
Where possible, attend your blood test between 7am and 12pm. Please wait until any short-term illness or infection has fully resolved before testing. Avoid intense exercise for 24–48 hours beforehand, as this can affect certain markers.
Fasting & Hydration
Fasting is not always required, but some tests may recommend it. If fasting is advised, avoid food for 8–12 hours before your appointment and drink water only. Stay well hydrated, as this helps with sample collection and accuracy.
Medications & Supplements
Continue prescribed medications unless advised otherwise by your clinician. Avoid vitamin, mineral, or biotin supplements for at least 24–48 hours before your test, as these can interfere with results. If you are unsure about any medication or supplement, please let us know before your appointment.
Hormones & Menstrual Cycle
For hormone-related tests, timing within your menstrual cycle may be important. If relevant, follow any specific guidance provided on your test page.
If you have any questions or special circumstances, our team is happy to advise before your appointment.