Measurements of 25-hydroxyvitamin D concentrations in archived dried blood spots are reliable and accurately reflect those in plasma.

Abstract

CONTEXT:

Recognition that vitamin D might be associated with many chronic diseases has led to large-scale epidemiological and clinical studies. Dried blood spots (DBS) are a useful resource for these studies. Consequently, accurate, efficient, and inexpensive assays to quantify 25-hydroxyvitamin D (25OHD) in DBS are required.

OBJECTIVE:

This study evaluated the validity and reliability of a liquid chromatography-tandem mass spectrometry assay for measuring 25OHD in archived DBS and compared measurements of 25OHD in DBS with those in plasma.

DESIGN AND PARTICIPANTS:

Sixty-two participants in the Melbourne Collaborative Cohort Study who had plasma and matching DBS stored since study entry in the early 1990s were randomly selected for a study calibrating 25OHD concentrations in DBS with plasma. As part of a study of vitamin D and mortality, cancer, and diabetes, we also assessed the reliability of measurements from DBS using 500 replicates placed randomly within 31 batches run over 15 months.

OUTCOME MEASURE:

25OHD concentrations were measured by liquid chromatography-tandem mass spectrometry.

RESULTS:

There was good agreement between measurements of 25OHD from DBS and plasma; R(2) = 0.73 from a regression of plasma concentration on DBS concentration. The within-batch and between-batch intraclass correlations from the 500 replicate measurements were 0.82 (95% confidence interval, 0.80, 0.85) and 0.73 (95% confidence interval, 0.68, 0.78), respectively.

CONCLUSIONS:

Measuring 25OHD in DBS is a valid and reliable alternative to measuring 25OHD in sera or plasma. A simple calibration model was developed to convert measurements from DBS to equivalent plasma measurements, thus enabling comparisons against clinical reference ranges and with studies using sera or plasma samples.

• Authors: Alicia K Heath, Elizabeth J Williamson, Peter R Ebeling, David Kvaskoff, Darryl W Eyles, Dallas R English
• Journal: The Journal of clinical endocrinology and metabolism (J Clin Endocrinol Metab) Vol. 99 Issue 9 Pg. 3319-24 (Sep 2014) ISSN: 1945-7197 [Electronic] United States
• PMID: 24885629 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Validation Study)

Chemical References

• Vitamin D
• 25-hydroxyvitamin D

Topics

• Adult
• Aged
• Calibration
• Chromatography, Liquid (methods, standards)
• Diabetes Mellitus (blood, epidemiology)
• Dried Blood Spot Testing (methods, standards)
• Female
• Humans
• Male
• Middle Aged
• Models, Biological
• Neoplasms (blood, epidemiology)
• Predictive Value of Tests
• Prospective Studies
• Reference Values
• Reproducibility of Results
• Risk Factors
• Tandem Mass Spectrometry (methods, standards)
• Vitamin D (analogs & derivatives, analysis, blood)