Vitamin B2 (Riboflavin) Test

A vitamin B2 (riboflavin) test measures the concentration of this essential water-soluble vitamin in the blood or urine, or it measures the activity of enzymes that depend on it (such as glutathione reductase in red blood cells). Riboflavin acts as a key coenzyme in oxidation-reduction reactions that produce cellular energy (in the Krebs cycle and the respiratory chain) and contributes to iron metabolism and the protection of cells from oxidative stress.