Details

Autor(en) / Beteiligte

• MOCK, Donald M
• HENRICH, Cindy L
• CARNELL, Nadine
• MOCK, Nell I

Titel

Indicators of marginal biotin deficiency and repletion in humans: validation of 3-hydroxyisovaleric acid excretion and a leucine challenge

Ist Teil von

• The American journal of clinical nutrition, 2002-11, Vol.76 (5), p.1061-1068

Ort / Verlag

Bethesda, MD: American Society for Clinical Nutrition

Erscheinungsjahr

2002

Quelle

Electronic Journals Library

Beschreibungen/Notizen

• The results of clinical studies have provided evidence that marginal biotin deficiency is more common than was previously thought. A previous study of 10 subjects showed that the urinary excretion of biotin and 3-hydroxyisovaleric acid (3HIA) are early and sensitive indicators of marginal biotin deficiency. Marginal biotin deficiency was experimentally induced and corrected to assess the utility of 3 indicators of biotin status: urinary excretion of biotin and 3HIA and the increase in 3HIA excretion after leucine loading. Eleven healthy adults consumed an egg white diet for 28 d. Blood and 24-h urine samples were collected before the start of the diet and twice weekly thereafter. In 5 subjects, an oral leucine challenge was performed weekly for 4 wk. After depletion, biotin status was restored with a general diet with or without a supplement containing 80 micro g biotin. Urinary excretion of biotin, bisnorbiotin, and biotin sulfoxides was determined by avidin-binding assay after HPLC. Excretion of 3HIA, an indicator of reduced activity of the biotin-dependent enzyme methylcrotonyl-CoA carboxylase (EC 6.4.1.4), was measured by gas chromatography-mass spectrometry. 3HIA excretion increased significantly with time on the egg white diet (P < 0.0001), as did 3HIA excretion in response to the leucine challenge (P < 0.002); the excretion of both biotin and bisnorbiotin decreased significantly with time (P < 0.0001). In most subjects, biotin status returned to normal after 1 wk of a general diet. Excretion of 3HIA and of biotin are early and sensitive indicators of biotin deficiency. 3HIA excretion after a leucine challenge is at least as sensitive.