Department of Clinical Biochemistry, Harrogate Foundation Trust, Harrogate, UK.
Department of Clinical Biochemistry, Manchester University NHS Foundation Trust, Manchester, UK.
Ann Clin Biochem. 2020 Jul;57(4):316-324. doi: 10.1177/0004563220926542. Epub 2020 Jun 4.
Calcium circulates bound to albumin and changes in albumin concentration will therefore affect total calcium measurements. In order to mitigate this, correction factors are frequently used. The most widely used correction equation was described by Payne and colleagues in 1973. This equation was derived from well-defined hospitalized patients' data. Current clinical practice is consistent with the general application of the adjusted calcium equation irrespective of clinical setting. This study aims to assess the validity of this approach by the derivation of a community care-specific adjusted calcium equation ('community equation') and the comparison of its performance to a hospitalized patient equation and ionized calcium.
Retrospective data were collected according to Payne's criteria from an inpatient and community care setting. Data were used to derive the two equations: the in-patient equation and community equation. The outcome of these equations was compared with ionized calcium obtained from 123 healthy participants.
The community equation correctly identified the calcium status of 92% of the 123 healthy participants, while the inpatient equation identified 46% only. Regression analysis against ionized calcium showed a higher R for the community equation than for the inpatient equation. Furthermore, we have shown that mean albumin and calcium concentrations are significantly different between these two populations.
In this study, we found that the diagnostic accuracy of the adjusted calcium equation in ambulant patients was improved by the derivation of a population-specific equation for the community care setting.
钙与白蛋白结合循环，白蛋白浓度的变化将因此影响总钙的测量。为了减轻这种影响，经常使用校正因子。最广泛使用的校正方程是由 Payne 及其同事于 1973 年描述的。该方程源自明确界定的住院患者数据。目前的临床实践与校正钙方程的一般应用一致，无论临床环境如何。本研究旨在通过推导特定于社区护理的校正钙方程（“社区方程”）来评估这种方法的有效性，并将其性能与住院患者方程和离子钙进行比较。
根据 Payne 的标准，从住院和社区护理环境中收集回顾性数据。使用这些数据推导出两个方程：住院患者方程和社区方程。将这些方程的结果与从 123 名健康参与者中获得的离子钙进行比较。
社区方程正确识别了 123 名健康参与者中 92%的钙状态，而住院患者方程仅识别了 46%。与离子钙的回归分析表明，社区方程的 R 值高于住院患者方程。此外，我们还表明，这两个人群的平均白蛋白和钙浓度存在显著差异。
在这项研究中，我们发现通过为社区护理环境推导特定于人群的方程，校正钙方程在非卧床患者中的诊断准确性得到了提高。
