Study Findings May Improve Diagnosis of Vitamin D Deficiency


Investigators of the study aimed to determine whether the analytical performance specifications of 24,25(OH)2D could be generated.

The findings from a new study may lead to more accurate diagnosis of vitamin D deficiency. Investigators from the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC-IOF) and the International Osteoporosis Foundation have published findings that determined the analytical performance specifications of 24,25-dihydroxyvitamin D (24,25(OH)2D) examination.1

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Investigators explored the metabolites in the degradation pathways of vitamin D, which gained importance recently, according to the investigators. The simultaneous quantitation of 25-hydroxy vitamin D (25(OH)D) and 24,25(OH)2D has been proposed as a new approach to define vitamin D deficiency, but there have been no data available on 24,25(OH)2D biological variation to date.1

“This study expands our understanding of the degradation pathways of vitamin D in healthy individuals and, importantly, defines for the first time the analytical performance specifications for 24,25(OH)2D examinations. Given the growing interest in this metabolite, some laboratories or manufacturers may aim to develop specific methods for its determination, and these findings are thus necessary prerequisites for their validation,” Etienne Cavalier, a professor of Clinical Chemistry at the University of Liège in Belgium and chairman of the IFCC-IOF Committee for Bone Metabolism, said in a statement.1

In the study, investigators evaluated the biological variation of 24,25(OH)2D using the European Biological Variation Study cohort samples. They aimed to determine whether the analytical performance specifications of 24,25(OH)2D could be generated.1

Six laboratories in Europe were included in the study, totaling 91 healthy individuals. The concentrations of 24,25(OH)2D and 25(OH)D in EDTA plasma were examined weekly for up to 10 weeks and with a validated liquid chromatography and mass spectrometers method.1

Investigators calculated Vitamin D Metabolite Ration, with the formula 24,25(OH)2D divided by 25(OH)D times 100, at each time point.1

The findings demonstrated that the linear regression of the mean 24,25(OH)2D concentrations of each blood sample showed individuals who were not in a steady state. Over time, variations of 24,25(OH)2D were significantly positively associated with the slopes of 25(OH)D concentrations over time and the concentration of 25(OH)D of the individuals at baseline.1

Additionally, they found that it was also negatively associated with body mass index.1

The variation of the 24,25(OH)2D concentration in individuals over the 10-week period was 34.6%. The methods that would detect a significant change linked to the natural production of 24,25(OH)2D over this period would need a relative measurement uncertainty of less than 14.9%. While at p<0.01, the measurement uncertainty should be less than 10.5%.1

“This study demonstrates the huge value of international collaboration, bringing together key expertise from IFCC and IOF, and has established important technical parameters which will facilitate clinical validation of [24,25(OH)2D] measurement, and potentially lead to more accurate assessment of vitamin D deficiency,” Nicholas Harvey, director of the MRC Lifecourse Epidemiology Centre at the University of Southampton and chair of the IOF Committee of Scientific Advisors, said in the statement.1

According to data from the National Health Nutrition Examination Surveys, approximately two-thirds of the population had sufficient vitamin D levels, with one-quarter being at risk of inadequacy and 8% at risk of vitamin D deficiency, from 2001 to 2006.2

Additionally, the risk of vitamin D deficiency increased between 1988 until 1994 and 2001 between 2002.2


1. New study defines analytical performance specifications for 24,25-dihydroxyvitamin D examinations. News release. EurekAlert. May 23, 2023. Accessed June 9, 2023.

2. Vitamin D Status: United States, 2001–2006. Centers for Disease Control and Prevention. March 2011. Updated November 6, 2015. Accessed June 8, 2023.

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