Biologically active vitamin B2 (riboflavin) is a test based on a microbiological method that measures the total vitamin B2 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 more excellent value. It 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.
Vitamin B2 is a flavin-nucleotide component that transports hydrogen ions and electrons. It is an essential coenzyme for metabolizing carbohydrates, fats, and proteins. The biological form of vitamin B2 is riboflavin-5-phosphate. The most critical vitamin B2 derivatives are flavin mononucleotide (FMN) and flavin-adenine dinucleotide (FAD). About 60% of FAD and FMN in blood are protein-bound; only about 0.5–2% occur in free form. Riboflavin-5-phosphate, FMN, and FAD are transported in the plasma by various proteins, including albumin, fibrinogen, riboflavin-binding protein, and other globulins. Although vitamin B2 is eliminated regularly in the urine, its determination in urine samples is not recommended because of fluctuations in the concentration.
Indications for vitamin B2 determination:
- Chronic diarrhea
- Preeclampsia
- Hypothyroidism
- Diabetes mellitus
- Alcohol abuse
- Anorexia
- Lactose intolerance
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 unique 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.
