SELENIUM, whole blood
B-Se ATK 8011

Selenium is a crucial trace element vital for the body’s functioning, and its presence in food varies significantly based on geographical factors, mainly the selenium content within the soil and the feed used. In plants and animals, selenium forms associations with amino acids such as cysteine and methionine. Inorganic selenium forms, including selenate and selenite, are also encountered. The highest concentrations of selenium are found in muscle tissues, the liver, kidneys, and testicles. The absorption of selenium from the intestines is contingent on its chemical composition and other compounds in the diet, although the precise mechanism remains uncertain.

Within the body, selenium plays a pivotal role in antioxidant defense mechanisms. It engages in reduction reactions, effectively neutralizing harmful peroxides through enzymes like glutathione peroxidase (GSH-Px). Selenium’s significance extends to oxidation-reduction processes, facilitated by enzymes like thioredoxin reductase. Additionally, selenium contributes to thyroid hormone metabolism, influencing the activity of iodotyrosine deiodinases that aid in converting the inactive thyroxine hormone into the active triiodothyronine hormone, as well as deactivating thyroid hormones when necessary. Selenium contributes to heart protection, counteracts the adverse effects of heavy metals, and takes part in immune defense. Notably, selenium exhibits chemical similarities to sulfur and can substitute sulfur in amino acids.

The level of selenium in whole blood serves as a reflection of the body’s selenium status.


Investigating selenium levels in the body. Suspected selenium deficiency. 


5 mL of lithium or sodium heparin blood. 

Mix the sample well. The tube must not contain any clots. Take trace element samples last in order to cleanse the sampling needle of possible trace element residues. If this is the only test requisition, first take one extra tube.

No fasting is needed. No trace element supplements 12 hours before sampling.

Storage and delivery

Ship at room temperature on sampling day (shipping Mon-Thu). Store frozen over the weekend, ship at room temperature.


ICP-MS, Accredited method

Turnaround time

10 weekdays 

Reference ranges, calculated

adults 1.1 – 2.8 µmol/L
under 20 yrs 1.2 – 2.2 µmol/L 

The same sample can be used to measure Cu, K, Mg, Mn, P and Zn. 

The reference areas have been calculated from the Mineral Laboratory Milan research database. Outliers that significantly differed from the reference distribution were excluded. A mid-percentile range of 90% has been established based on the refined dataset. The most recent update was in 2017.

Interpretation of results

Selenium-rich dietary sources encompass meat, fish, whole grains, legumes, mushrooms, and nuts, with Brazil nuts standing out for their particularly high selenium content. It’s worth noting that organic products tend to contain lower selenium levels compared to conventional foods, as selenium is often added to fertilizers to ensure adequate intake.

Selenium deficiency can arise in regions where endemic selenium deficiency is prevalent. Notably, cardiomyopathy, referred to as Keshan’s disease, has been identified in China, especially affecting children and young women. This condition is attributed not only to selenium deficiency but also to viral infections and vitamin E inadequacy. Similarly, Kashin-Beck articular cartilage disease, also endemic in China, is linked to selenium deficiency. A combined shortage of selenium and iodine has been linked to cretinism. Additionally, insufficient selenium intake has been associated with chronic ailments like cancer, cardiovascular diseases, and asthma.

Prolonged excessive selenium consumption exceeding the daily recommended dose of 900 µg can result in selenium poisoning. Symptoms initially include malaise, weakness, and diarrhea, progressing to hair loss, alterations in nails and teeth, along with skin and nervous system damage. Excess selenium is eliminated through urine, but exceptionally high levels can also be excreted through the lungs. The presence of dimethylselenium excreted through the lungs imparts a garlic-like odor to the breath. The recommended maximum safe daily selenium intake for adults is 300 µg.


Last update 8.8.2023