Infants biotinidase

Lower-than-normal activities are often obtained in newborns and in preterm and small-for-age infants [12, 23], especially if they have neonatal jaundice [22]. Plasma biotinidase activity increases with advancing age, reaching maximum values at between 20 and 40 days [23]. 

Suormala T, Wick H, Baumgartner ER (1988) Low biotinidase activity in plasma of some preterm infants possible source of false-positive screening results. Eur J Pediatr 147 478-480... 

Children with biotinidase deficiency are usually treated with 5-10 mg of oral biotin. We often use the same dose for infants as we do for older children. This obviously means that the dose of biotin per body weight is decreasing as the child gets older. How might one determine if the dose of biotin is adequate or if higher doses are necessary ... 

The problem is a functional deficiency of biotin, due both to inability to release free biotin from dietary biocytin and also to failure of the normal recovery of free biotin by biotinidase action on the biocytin released by proteolysis of biotin-containing enzymes. Normal intakes of biotin are inadequate to meet the requirements of these patients the provision of pharmacological doses of free biotin provides an adequate amount to meet requirements without the need for reutUization. The delayed development of clinical and biocheimcal abnormalities is a result of the accumulation of biotin by the fetus, so that at birth the infant has adequate stores of the vitamin. 

Biotinidase deficiency is an autosomal recessive disorder with an estimated incidence of 1 in 72,000-126,0(X). Many newborn-screening programs of genetic diseases include testing for this enzyme. Prompt treatment with oral biotin administration of 5-20 mg/d in affected infants will prevent clinical consequences. If the treatment is delayed, neurological manifestations (e.g., hearing loss and optic atrophy) and developmental delay occur and may not revert to normal. 

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