Urinary biotin analogs increase in humans during chronic
supplementation: the analogs are biotin metabolites.
Mock, Donald M., and Greg M. Heird.
Department of Pediatrics, Section of Gastroenterology, University
of Arkansas for Medical Sciences, Arkansas Children's Hospital,
Little Rock, AR
APStracts 3:0180E, 1996.
In human subjects, the metabolic origins of bisnorbiotin and biotin
sulfoxide were determined by measuring the urinary excretion of each
after chronic administration of large oral doses of biotin. For two
weeks, fourteen adult volunteers consumed 1200 [mu]g biotin per day,
an amount approximately 20 times the daily dietary intake. Using an
HPLC/avidin-binding assay in untimed urine samples obtained before
the first dose of biotin and after the fourteenth dose,
concentrations of biotin, bisnorbiotin, and biotin sulfoxide were
measured. Excretion was expressed as concentration ratios to urinary
creatinine. Bisnorbiotin and biotin sulfoxide excretion increased 85
fold (P < 0.0001) and 114 fold (P < 0.0001), respectively.
The molar percentages of bisnorbiotin and biotin sulfoxide decreased
from 28 % to 14 % (p = 0.006) and from 9 % to 5 % (p = 0.017),
respectively. These data provide evidence that the bisnorbiotin and
biotin sulfoxide found in human urine are biotin metabolites.
Further, we infer that chronic consumption of large amounts of biotin
does not substantially saturate the human biotin pathways of
biotransformation.
Received 30 May 1996; accepted in final form 14 August 1996.
APS Manuscript Number E264-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996