ABSTRACT
Biotin occurs widely in foods, but usually at very low concentrations. Chronic hemodialysis may produce a biotin deficiency due to loss of free biotin in the dialysate. Holocarboxylase synthetase is essential for the transfer of biotin to the apocarboxylase for their activation. Determination of biotin in blood and other test materials requires that the bound biotin must be released by papain digestion or by sulfuric acid hydrolysis. The urinary excretion of both biotin and bisnorbiotin decreased significantly during the 3-week depletion period; however, serum concentrations of biotin did not decrease significantly. Biotin deficiency when observed is usually in association with genetic defects, drug interactions, prolonged total parenteral nutrition, or unusual diet habits. Biotin analogues identified in human urine include bisnorbiotin, biotin-dl-sulfoxide, and bisnorbiotin methyl ketone. The flagellate Ochromonas danica has been used successfully as the test organism to measure biotin concentrations in blood, urine, and other biological tissues.
