Biologically active vitamin Β7 (Vitamin Η, Biotin) is a test based on a microbiological method that measures the total vitamin Β7 content in a blood sample.
What are the benefits of measuring Biologically Active Vitamins?
This test measures the biologically active in vivo metabolites of B vitamins. Vitamins' biological action (bioactivity) has greater value and is a more representative indication of their active concentration than the simple chemical measurement of their levels, especially in cases where these indications are used to determine substitution therapy or to check a therapeutic intervention.
Biotin (vitamin H) is widespread in bacteria, fungi, higher plants, and animal tissues. The central part of biotin in food is covalently bound to protein, with only a small part being freely available. During digestion, biocytin (biotinyl-lysin) is released from the proteins and can, similarly to biotin, quickly be taken up from the intestine. The enzyme biocytinase then releases biotin from biocytin in plasma and erythrocytes and is available as a prosthetic group for several biotin-dependent enzymes. The daily biotin requirement is difficult to estimate because a healthy intestinal flora endogenously synthesizes biotin and thereby helps to satisfy this need. Recent findings suggest that adults need 100–200µg biotin daily. Supplementation on a milligram scale significantly improves chronic hemodialysis patients' neuropathology and glucose metabolism.
Biotin deficiency
Symptoms of biotin deficiency are caused by damage to the intestinal flora or extreme diets (e.g., frequent consumption of raw eggs). Consequences of biotin deficiency include dermatitis, hair loss, anorexia, muscular hypotonia, depression, and sexual dysfunction.
Indications for a determination of biotin
- Defects in enzymes (e.g., genetic deficiency of biotinidase)
- Short gut syndrome
- Altered intestinal flora
- Malnutrition
How are Biologically Active Vitamins measured?
To test the biologically active vitamins, the blood sample is subjected to an enzymatic pre-treatment and then placed in microplates containing microorganisms sensitive to these vitamins (e.g. Lactobacillus fermentum, Lactobacillus rhamnosus, Lactobacillus leichmanii, Saccharomyces cerevisiae). The nutrient medium, specific and unique to each vitamin, contains all the necessary ingredients for the growth of microorganisms, except for the vitamin to be measured. When the patient's blood is added to the material, the microorganisms grow until the examined vitamin is depleted. The growth of microorganisms is measured after 72 hours of incubation in a special multi-channel analyzer and compared to standard concentrations of vitamins. The bioactivity of the tested vitamin is directly proportional to the measured growth of microorganisms.
