Interlaboratory Variation of Vitamin D Metabolite Measurements

Jongen, M.J.M.; Vijgh, W.J.F. van der; Beresteyn, E. C. H. van; Berg, Henk van den; Bosch, R.; Hoogenboezem, Theo; Tj, Visser; Netelenbos, J. C.

doi:10.1515/cclm.1982.20.10.753

Cited by 15 publications

(13 citation statements)

References 4 publications

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“…The routine 25(OH)D assays are much better standardized now a b than 10 years ago. Interlaboratory studies at that time [6,7] showed a much larger variation between laboratories than this study. However, definition of vitamin D deficiency or sufficiency in absolute terms may still be misleading as there is no international standard and cross-calibration is not common practice.…”

Section: Discussioncontrasting

confidence: 48%

“…As 25-hydroxyvitamin D (25(OH)D) is the main circulating metabolite, the assays for 25(OH)D in human serum samples should be precise and distinguish between vitamin D deficient and replete states [5]. In the past, several interlaboratory comparisons have led to the conclusion that most assays are able to discriminate between low and average serum 25(OH)D concentrations [6,7]. However, these assays have not well been standardized.…”

Section: Introductionmentioning

confidence: 99%

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An International Comparison of Serum 25-Hydroxyvitamin D Measurements

Lips

Chapuy

Dawson‐Hughes

et al. 1999

Osteoporosis International

351

198

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Vitamin D status is usually assessed by measuring the serum 25-hydroxyvitamin D (25(OH)D) concentration. This mainly depends on sunshine exposure, nutrition and age. Interlaboratory variation may hamper comparison between results from different populations. This study reports cross-calibration of the 25(OH)D assays of five laboratories. In study 1, serum 25(OH)D was measured with three different assays in 104 serum samples from a large vitamin D supplementation study. The mean serum 25(OH)D level was 80% higher when measured by competitive protein binding (CPB) assay than by high-performance liquid chromatography (HPLC), while radioimmunoassay (RIA) gave intermediate values. The highest correlation was observed between RIA and HPLC (r = 0.84, p <0.01). Of the serum 25(OH)D values in the lowest quartile by HPLC, 25% were not recognized by CPB and 21% were not recognized by RIA as belonging to the lowest quartile. In study 2, the five laboratories analyzed serum 25(OH)D in eight serum samples covering the concentration range very low to high, with five different assays. The differences between the mean values for serum 25(OH)D between the laboratories with the highest and lowest values was 38%. The ranking order of individual samples according to the serum 25(OH)D value was very similar in all laboratories. The results show that 25(OH)D values from different laboratories can not be assumed to be comparable unless a careful cross-calibration has been performed.

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Section: Discussioncontrasting

confidence: 48%

Section: Introductionmentioning

confidence: 99%

An International Comparison of Serum 25-Hydroxyvitamin D Measurements

Lips

Chapuy

Dawson‐Hughes

et al. 1999

Osteoporosis International

351

198

View full text Add to dashboard Cite

show abstract

“…The international Vitamin D External Quality Assessment Scheme (DEQAS) was established in 1989 after several surveys reported poor performance among laboratories measuring 25-OHD [3][4][5] and 1,25-dihydroxyvitamin D (1,25(OH) 2 D) [4]. The scheme has over 180 participants in 23 countries.…”

Section: Introductionmentioning

confidence: 99%

The anomalous behaviour of exogenous 25-hydroxyvitamin D in competitive binding assays

Carter

Jones

Berry

2007

The Journal of Steroid Biochemistry and Molecular Biology

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“…Definitions of 25(OH)D deficiency and insufficiency may vary considerably with seasons due to sunlight exposure [8,15,22,23]. Also, the variability in the different vitamin D assays used in Europe and those that include a high performance liquid chromatography (HPLC) extraction technique may result in lower vitamin D levels than assays commonly used in the United States [4,24,25]. Gloth et al [14] defined the lowest acceptable level of 25(OH)D as 15 ng/ml, based on iPTH levels as an index of 25(OH)D repletion whereas data from European studies report a lower range of <12 ng/ml and 15 ng/ml [26,27].…”

mentioning

confidence: 99%

Calcidiol and PTH Levels in Women Attending an Osteoporosis Program

Haden

Fuleihan

Angell

et al. 1999

Calcified Tissue International

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We performed a retrospective study of 237 patients attending a specialty osteoporosis practice. Secondary causes for reduced bone mineral density (BMD) were evaluated in 196 postmenopausal women and 41 premenopausal women; mean age was 56 +/- 13.8 years (mean +/- SD). BMD was measured by dual-energy X-ray absorptiometry (DXA) (QDR 1000W/2000 Hologic). Levels of intact parathyroid hormone (iPTH), calcidiol [25(OH)D], thyroid-stimulating hormone, and 24-hour urinary calcium were measured, and serum and urine protein (SPEP and UPEP) electrophoresis were performed. Overall, 16% of our patients had 25(OH)D levels <15 ng/ml, the lowest acceptable vitamin D level without a concomitant rise in iPTH levels. Among the osteoporotic patients (T score <-2.5 SD), 17% had 25(OH)D levels <15 ng/ml and 7% <10 ng/ml. Among the osteopenic patients (-2.5 < T < -1.0 SD), 11% had 25(OH)D levels <15 ng/ml. Seventeen percent of patients with Z score 65 pg/ml, upper normal limit of assay) were present in 11.5%, and hyperthyroidism in 4%. A 25(OH)D level of <25 ng/ml in women (n = 86) with no known secondary causes of low BMD was associated with an iPTH level above 49 pg/ml. The measurement of 25(OH)D levels is recommended in the evaluation of secondary causes for reduced BMD. Supplementation with vitamin D appears needed to keep 25(OH)D above 25 ng/ml, the level required to prevent increments in iPTH levels.

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Interlaboratory Variation of Vitamin D Metabolite Measurements

Cited by 15 publications

References 4 publications

An International Comparison of Serum 25-Hydroxyvitamin D Measurements

An International Comparison of Serum 25-Hydroxyvitamin D Measurements

The anomalous behaviour of exogenous 25-hydroxyvitamin D in competitive binding assays

Calcidiol and PTH Levels in Women Attending an Osteoporosis Program

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