RESUMO
Because estimates of the biotin requirement for infants currently are based on the biotin concentration in human milk, we sought to determine whether inactive biotin metabolites are present. Samples were collected for 7 weeks post partum from 15 healthy women. Biotin and the inactive metabolites bisnorbiotin and biotin sulfoxide were measured by means of a high-performance liquid chromatography avidin-binding assay. At 8 days post partum the proportion of biotin was 44%, bisnorbiotin 48%, and biotin sulfoxide 8%. Although biotin content increased post partum (p < 0.003), the metabolites remained an important portion of the total providing evidence that accurate measurement of biotin in human milk requires an assay that is specific for biotin.
Assuntos
Biotina/análise , Leite Humano/química , Adulto , Biotina/análogos & derivados , Biotina/metabolismo , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Fenômenos Fisiológicos da Nutrição do Lactente , Recém-Nascido , Necessidades Nutricionais , Período Pós-Parto , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Fatores de TempoRESUMO
Biotin deficiency associated with total parenteral nutrition is an emerging clinical problem; criteria for diagnosis and dosage for treatment are unclear. We have diagnosed and successfully treated biotin deficiency in three patients. Each patient had alopecia totalis, hypotonia, and developmental delay. Two developed the characteristic scaly periorificial dermatitis; one had only an intermittent scaly rash on the cheeks and occipital scalp. Zinc and essential fatty acid supplements were adequate; serum zinc levels and triene/tetraene ratios confirmed sufficiency of these nutrients. None of the patients received biotin prior to diagnosis, and each had decreased excretion of urinary biotin and increased urinary excretion of organic acids diagnostic of deficiency of two biotin-dependent enzymes (methylcrotonyl-coenzyme A carboxylase and priopionyl-coenzyme A carboxylase). Only one patient had a plasma biotin concentration below the normal range (Ochromonicas danica assay). The rash, alopecia, and neurologic findings responded dramatically to biotin therapy (100 micrograms/day in all patients; an initial larger dose of 1 mg/day for 1 week plus 10 mg/day for 7 weeks in one patient), and did not recur. However, abnormal organic acid excretion persisted in one patient who did not receive the larger dose. We conclude that plasma biotin concentration does not reflect biotin status in all cases and speculate that the biotin supplement currently recommended for pediatric patients (20 micrograms/day) may not be adequate therapy for biotin deficiency and might not even be adequate to maintain normal biotin status during TPN.