The measurement of intracellular selenium, performed by measuring the concentration of selenium in red blood cells, estimates the actual levels of the metal within the cells.
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Selenium (Se) is an essential trace mineral element in humans but is toxic when consumed excessively. It is usually sourced from seafood, peas, lentils, beans, whole grains, organic meats, dairy products, and vegetables. An adult contains 20 mg of selenium, which is stored mainly in organs and tissues in different amounts: 30% in the liver, 30% in muscle, 15% in the kidney, 10% in plasma, and 15% in other organs. Selenium is present in nature and organisms in organic or inorganic forms. The primary organic forms are selenomethionine and selenocysteine, while the inorganic forms are selenite, selenide, selenate, and selenium.
It is incorporated into proteins in the form of selenocysteine and selenomethionine, forming selenoproteins. Selenium is an essential element of selenoproteins involved in redox catalytic activity and structural and transport functions. Selenium is linked to antioxidant defense, immune function, thyroid hormone synthesis, testosterone metabolism, DNA structure, vitamin E modulation, anticancer and inflammatory processes, and muscle performance.
Among the different selenoproteins, the enzymes glutathione peroxidase (GPx) and glutathione reductase (GR) are well-known in sports. These enzymes comprise the glutathione redox cycle (GSH), an essential antioxidant system in the body. Trace mineral element concentrations are usually under rigorous homeostatic control. However, selenium metabolism could be modified during physical exercise.
Selenium status can be assessed in several compartments. It can be measured directly in plasma, serum, blood, urine, hair, nails, and tissues such as the kidney and liver. It can also be measured indirectly by GPx activity. However, evaluating selenium status in an isolated compartment does not seem adequate to obtain a complete assessment. Plasma or serum selenium could reflect the short-term status, whereas erythrocyte selenium could indicate the long-term status.
Measurement of Intracellular Trace Elements
Measuring intracellular metals and trace elements within red blood cells (RBCs) is an excellent method for assessing the deficiency or excess of elements with important functions within cells or cell membranes. It is also used to assess the status of vital elements with essential intracellular functions, such as potassium, magnesium, copper, selenium, and zinc.
