Selenium
A selenium blood test measures levels of this essential trace element, which plays a vital role in thyroid function, immune health, and antioxidant defense throughout the body.
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What this test measures
Selenium is a trace element essential for human health that plays a critical role in various physiological processes and is commonly assessed through its concentration in serum. As an integral component of selenoproteins, selenium is pivotal in antioxidant defense systems, thyroid hormone metabolism, and immune function. The body needs only small amounts of this mineral, but selenium deficiency can lead to serious health complications.
Serum selenium levels can be used in the determination of deficiency or toxicity. Plasma and serum contains 75 percent of the selenium measured in whole blood and reflects recent dietary intake. This test measures the concentration of selenium in blood serum or plasma, providing healthcare providers with important information about an individual's selenium status. Selenium is an essential element; it is a cofactor required to maintain activity of glutathione peroxidase (GSH-Px), an enzyme that catalyzes the degradation of organic hydroperoxides. The absence of selenium correlates with loss of GSH-Px activity and is associated with damage to cell membranes due to accumulation of free radicals.
Who should consider this test
You might consider this test if you are experiencing any of the following:
- Individuals experiencing unexplained fatigue, muscle weakness, or hair loss, as these may be early signs of selenium deficiency that can affect overall energy levels and physical wellbeing.
- Those with thyroid disorders or thyroid-related symptoms, since selenium is essential for proper thyroid hormone production and metabolism, and deficiency may contribute to thyroid dysfunction.
- People with compromised immune function who experience frequent infections, as selenium plays a crucial role in supporting immune system responses and protecting against oxidative stress.
- Individuals receiving total parenteral nutrition (TPN) or those with gastrointestinal disorders that may affect nutrient absorption, as these conditions can increase the risk of selenium deficiency.
- Those living in areas with selenium-poor soil or following restrictive diets that may limit selenium intake from natural food sources, particularly if symptoms of deficiency are present.
- People concerned about potential selenium toxicity from excessive supplementation or environmental exposure, as elevated levels can cause serious health complications including cardiovascular and neurological symptoms.
What to expect
Preparation
No special preparation or fasting is required for the selenium blood test. Individuals should inform their healthcare provider about any selenium supplements they are taking, as these may affect test results.
Sample Type
The test requires a simple blood draw from a vein in the arm. The blood sample must be collected in a special trace element-free tube to prevent contamination that could affect results.
Collection
The blood draw typically takes just a few minutes and is performed by trained laboratory personnel. Special care is taken to avoid contamination during collection and processing.
Turnaround
Results are typically available within 2-3 business days after the laboratory receives the sample. No doctor visit is required to order this test.
Understanding your results
The typical reference range for serum selenium varies, but is generally considered to be between 70 and 150 ng/mL. Results outside this range may indicate either deficiency or excess selenium levels that could affect health.
| Population | Reference Range | Notes |
|---|---|---|
| Adults | 70-150 ng/mL (70-150 mcg/L) | Normal range may vary slightly between laboratories |
| Children | Lower than adult ranges | Age-dependent values; children require less circulating selenium |
Reference ranges may vary by laboratory and individual factors. Results should be interpreted by a healthcare provider in the context of your overall health.
What does a “Low” result mean?
In the state of selenium deficiency associated with loss of glutathione peroxidase activity, the serum concentration is usually below 40 mcg/L. Low selenium levels may be associated with increased risk of certain health conditions. Myodegenerative diseases, such as muscle weakness, are often linked with moderate selenium deficiency. An insufficient selenium status has been associated with adverse mental health outcomes, including symptoms of depressed mood, increased anxiety, and heightened confusion. Selenium deficiency can occur endemically or as a result of sustained TPN or restricted diets and has been associated with cardiomyopathy and may exacerbate hypothyroidism.
What does a “High” result mean?
The most common clinical signs of chronically high selenium intakes, or selenosis, are hair loss and nail brittleness or loss. Other signs and symptoms include skin rash, nausea, diarrhea, fatigue, irritability, and nervous system abnormalities. High selenium levels may indicate excessive supplement intake, consumption of selenium-rich foods like Brazil nuts, or environmental exposure. At high doses (> 900 mcg/day), selenium causes toxicity. Symptoms of selenium toxicity are mainly gastrointestinal disturbances (eg, nausea, diarrhea). Other manifestations include hair loss, abnormal nails, dermatitis, peripheral neuropathy, fatigue, irritability, and a garlic odor of the breath.
Privacy & confidentiality
Your selenium test results are completely confidential and protected under HIPAA regulations. Results are not shared with insurance companies, will not appear on insurance billing statements, and are not added to your personal medical record unless you choose to share them with your healthcare provider.
Frequently asked questions
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CPT Code: 84255
This test may not be available in: NY, NJ, RI
This page is for informational purposes only and does not constitute medical advice. Always consult with a healthcare provider regarding any health concerns. LevelPanel does not diagnose, treat, or prescribe.
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Not sure if this is the right test? Contact our care team for guidance.