[Trends in Number of Vitamin B12- and D-determinations in the Netherlands].

OBJECTIVE:To gain insight into the volume of vitamin B12- and D-determinations over time.DESIGN:A retrospective cohort study.METHOD:Using declaration data of around 3.5 million insured Dutch citizens we examined the volume of vitamin B12- and D-testing between 2015-2019. Both trends in number and proportion of patients receiving a vitamin B12- and D determination were assessed.RESULTS:Between 2015-2019 the number of vitamin B12-determinations increased by 98,1% and the number of vitamin D-determinations by 112%. The proportion of patients receiving a determination increased from 4,8% to 8,4% for vitamin B12 and from 4,7% to 9,1% for vitamin D over the examined period.CONCLUSION:Both the number of and proportion of patients receiving a vitamin B12- and D-determinations increased over the examined time period. Our findings emphasize the need for proper patient and physician information regarding the indications which justify vitamin B12- or D testing, in order to reduce and prevent overtesting.