Recent Advances in the Quantitation of Vitamin D and Vitamin D Metabolites

Horst, Ronald L.

doi:10.1007/978-1-4613-2839-1_18

Cited by 3 publications

(2 citation statements)

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“…Serum 1,25(OHhD was measured by a nonequilibrium competitive protein binding assay based on a calf thymus receptor specific for both 1,25(OHhD 2 and 1,25(OHhD 3 (Incstar Corp.). The assay involved preliminary extraction with acetonitrile and purification with a C18-0H cartridge (17). The intra-and interassay coefficients of variation are 9 and 12%, respectively.…”

Section: Analytic Methodsmentioning

confidence: 99%

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Effect of Three Levels of Vitamin D Intake in Preterm Infants Receiving High Mineral‐Containing Milk

Koo,

Krug‐Wispe,

Neylan

et al. 1995

J. pediatr. gastroenterol. nutr.

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Summary:Very low‐birth weight (VLBW) infants fed high‐calcium and high‐phosphorus (10.74 and 6.93 mmol/MJ; 180 and 90 mg/100 kcal, respectively) infant formulas were randomized to one of three levels of vitamin D intake to approximate 200, 400, and 800 IU/day. Sixty‐two infants completed the study (24 to 29 days), with actual mean daily vitamin D intakes of 161, 361, and 766 IU, respectively. Outcomes were not different by group: gains in body weight, length and head circumference, serum calcium, magnesium, phosphorus, alkaline phosphatase, osteocalcin, 25‐hydroxyvitamin D, 1,25‐dihydroxyvitamin D, and urine calcium:creatinine and magnesium:creatinine ratios. There were no radiographic fractures and/or rickets. A subset of 19 infants was followed between 173 and 380 days to determine descriptively if there was any delayed effect of earlier manipulation of vitamin D intake. They were fed standard infant formulas with a vitamin D content of 400 to 420 IU/L. No significant differences were present among the three groups, and data were combined. Serum 25‐hydroxyvitamin D increased (p < 0.05), osteocalcin decreased (p < 0.05), and 1,25‐dihydroxyvitamin D decreased (p = 0.06) at follow‐up. Thus, for VLBW infants fed high‐calcium and high‐phosphorus milk, an average daily vitamin D intake as low as 160 IU maintains normal and stable vitamin D status and normal physical growth, biochemical and hormonal indexes of bone mineral metabolism, and skeletal radiographs versus randomized infants receiving about 400 or 800 IU of vitamin D per day. On follow‐up, vitamin D status remained normal for ≥ 6 months while infants received <400 IU of vitamin D per day.

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Section: Analytic Methodsmentioning

confidence: 99%

“…Serum 25-0HD was measured directly against a 25-0HD 3 standard by high-performance liquid chromatography. Preliminary steps included extraction of the serum sample with acetonitrile and prepurification using C18 and silica columns (17). The intraassay variance is 10%, and the interassay variance is 13%.…”

Section: Analytic Methodsmentioning

confidence: 99%