Biotin normal range

Table 1 Normal range for biotin and metabolites in human serum and urine ...

The average value in the 10 histologically normal lyophilized brains assayed for biotin was 230 i ig/mg with a range of 210-240 p(ig/mg. Values for biotin content of lyophilized rat brain were the same as those for human brain. 

In an investigation of the water-soluble vitamins in human skin,71 it was found that 15 individuals showed relatively small ranges (less than 2-fold) for vitamin B12, folic acid, and biotin about 2-fold ranges in the cases of riboflavin, niacin, and thiamine about a 4-fold range in the case of ascorbic acid, and more than a 5-fold range in the case of pantothenic acid. In another study72 it was found that the total choline content of normal skin varied in four individuals over approximately a 10-fold range 127 to 1200 ig. per gm. The variation in the free choline in the same individuals was relatively small. 

Electroencephalographic findings in individuals with untreated profound biotinidase deficiency have ranged from normal to markedly abnormal and are usually nonspecific. Demyelin-ation and other cerebral abnormalities have been seen in some children with biotinidase deficiency. These findings sometimes improve following biotin treatment. 

Biotinidase is also the major plasma binding protein for biotin. The pH optimum of the enzyme is 4.5 to 5.5, and its is in the micromolar range, compared with the nanomolar concentrations of biocytin, so it will have little enzymic activity in plasma. Rather, it functions as a transport protein for biotin, preventing its urinary excretion children with biotinidase deficiency (Section 11.2.3.1) excrete large amounts of both biocytin and free biotin. Biotin is covalently bound to biotinidase in plasma, as a thioester to a cysteine residue in the active site of the enzyme (see Figure 11.1). This thioester is formed only from biocytin, not free biotin, and is presumably the (normally transient)... 

A 30-year-old woman, a heterozygote for hypophosphatasia, who had been taking two tablets of a multivitamin formulation (pyridoxine hydrochloride 100 mg, riboflavin butyrate 30 mg, nicotinamide 40 mg, biotin 0.05 mg, ascorbic acid 100 mg) once daily for 6 years, had severe skin eruptions and pruritus on exposure to the sun. The minimum erythema doses for UVB (20 mJ/ cm ) and UVA (4 J/cm ) were lower than normal only for UVB (reference ranges 60-100 mJ/cm for UVB and below 10 J/cm for UVA). Patch and photopatch tests with the constituents of the tablets produced reactions to pjTidoxine and pjridoxal phosphate only. 

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