Department of Internal Medicine, Division of Endocrinology and Metabolism, United States.
Department of Pathology, Division of Laboratory Medicine. Saint Louis University School of Medicine, United States.
Clin Chim Acta. 2023 Apr 1;544:117353. doi: 10.1016/j.cca.2023.117353. Epub 2023 Apr 17.
The formula, referenced in major textbooks, for albumin corrected calcium [Calcium] may not accurately depict ionized calcium [ICa]. We evaluated the accuracy of unadjusted calcium [Calcium] and [Calcium], and developed a protocol for local laboratory adjustment of calcium for albumin.
Laboratory data were obtained from an electronic health record. Assessments were accuracy, false positive, and false negative rates. Clinical reliability was defined in "error zones" for calcium [Ca]: Zone A = Ca(normal), ICa(low); Zone B = Ca(low), ICa(normal); and Zone C = Ca(normal), ICa(high), Zone D = Ca(high), ICa(normal).
A linear regression from 468 laboratory tests was used to derive a formula for "revised corrected calcium" [Calcium ] over a range of albumin concentrations where, [Calcium ] = plasma calcium + [(4- Albumin ]*(plasma calcium *0.052)]. [Calcium] vs [Calcium] decreased zone B errors 12%, [95%CI;8-15%], vs 44% [95%CI;37-50%], p < 0.001. However, [Calcium] vs [Calcium] increased zone A error (60%,[95%CI;42-78%], vs 7% [95%CI;1-13%], p < 0.001). [Calcium ] decreased zone A errors (15%, [95%CI;6-24%]) vs [Calcium ] (60% [95%CI;42-78%], p < 0.001) and Zone D errors from 9% [95%CI;6-12%] to 2% [95%CI;1:5%, p < 0.001].
[Calcium] is unreliable in hypo- or hypercalcemia. We provide a protocol for locally derived correction of calcium for albumin.
主要教科书上引用的白蛋白校正钙[Calcium]公式可能无法准确描述离子钙[ICa]。我们评估了未调整钙[Calcium]和[Calcium]的准确性，并制定了用于白蛋白校正钙的局部实验室调整方案。
从电子健康记录中获取实验室数据。评估的准确性、假阳性和假阴性率。钙[Ca]的“误差范围”定义了临床可靠性：区域 A=Ca（正常），ICa（低）；区域 B=Ca（低），ICa（正常）；区域 C=Ca（正常），ICa（高），区域 D=Ca（高），ICa（正常）。
使用 468 项实验室检测的线性回归得出了一个白蛋白浓度范围内的“修正校正钙”[Calcium]公式，其中[Calcium]=血浆钙+[（4-白蛋白）（血浆钙0.052）]。[Calcium]与[Calcium]相比，区域 B 误差减少了 12%（95%CI；8-15%），而 44%（95%CI；37-50%），p<0.001。然而，[Calcium]与[Calcium]相比增加了区域 A 的误差（60%，95%CI；42-78%），而 7%（95%CI；1-13%），p<0.001）。[Calcium]降低了区域 A 的误差（15%，95%CI；6-24%），而[Calcium]则增加了 60%（95%CI；42-78%），p<0.001）和区域 D 的误差从 9%（95%CI；6-12%）降至 2%（95%CI；1-5%），p<0.001）。
在低钙血症或高钙血症时，[Calcium]不可靠。我们提供了一种用于局部白蛋白校正钙的方案。
