Introduction: 25-hydroxyvitamin D (25-OH-D) is essential for calcium homeostasis and bone health, with increasing evidence suggesting associations with non-skeletal diseases. However, the lack of consensus on optimal concentrations and laboratory variability has led to clinical uncertainty and excessive testing. This study evaluates the impact of demand management strategies and revised cut-off points on test volumes, unperformed determinations, and cost savings.

Material and methods: A retrospective study (January 2015-May 2024) analyzed all 25-OH-D requests. Concentrations of 25-OH-D were measured using electrochemiluminescence assays on a Cobas C8000. An annual trend analysis of 25-OH-D test requests was performed to evaluate changes in demand. In 2018, vitamin D deficiency prevalence was assessed according to three cut-off values (75, 50 and 30 nmol/L). We assessed the impact of demand management rules, implemented in May 2022, to reduce unnecessary testing. The follow-up testing rate was calculated as the proportion of repeat tests within 12 months after determination.

Results: There was 25-OH-D testing increased from 10,830 in 2015 to nearly 85,000 in 2023. Demand management strategies led to 12,406 rejections in 2022 (from May onwards), 16,809 in 2023, and 7566 in 2024 (until May), saving €85,600. Follow-up testing rates dropped from ~15% before 2022 to ~5% afterward. Lowering the deficiency threshold from 75 to 50 nmol/L reduced deficiency diagnoses from > 70% to < 50%; at 30 nmol/L, rates could drop to ~10-11%.

Conclusions: Demand management strategies effectively reduce unnecessary testing and healthcare costs. Establishing appropriate reference values prevents overestimation of vitamin D deficiency, optimizing clinical and economic outcomes.

Keywords: cost savings; demand management guidelines; reference values; vitamin D; vitamin D deficiency.

Croatian Society of Medical Biochemistry and Laboratory Medicine.

简介： 25-羟基维生素D（25-OH-D）对于钙稳态和骨骼健康至关重要，越来越多的证据表明它与非骨骼疾病有关。然而，关于最佳浓度缺乏共识以及实验室变异性导致了临床不确定性和过度检测的问题。本研究评估了需求管理策略和修订后的切点值对检测量、未执行测定次数及成本节约的影响。

材料与方法： 一项回顾性研究（2015年1月-2024年5月）分析了所有25-OH-D的请求。使用Cobas C8000电化学发光法测量25-OH-D浓度。对每年的25-OH-D测试请求趋势进行了年度趋势分析，以评估需求的变化情况。在2018年，根据三个切点值（75、50和30 nmol/L）评估了维生素D缺乏症的发生率。我们还评估了从2022年5月起实施的需求管理规则对减少不必要的测试的影响。后续检测率为测定后12个月内重复测试的比例。

结果： 25-OH-D的检测量从2015年的10,830上升到了2023年的近85,000次。需求管理策略导致在2022年（从五月起）有12,406次拒绝测试，在2023年有16,809次，以及在2024年（直到五月份）有7566次，节省了€85,600。后续检测率从2022年前的大约15%下降到了其后的约5%。将缺乏阈值从75降至50 nmol/L后，维生素D缺乏的诊断从大于70%减少到小于50%，在30 nmol/L时，比率可能降低至大约10-11%。

结论： 需求管理策略有效减少了不必要的测试和医疗保健成本。建立适当的参考值可以防止维生素D缺乏的过度评估，从而优化临床和经济效益。

关键词： 成本节约；需求管理指南；参考值；维生素D；维生素D缺乏症。