Measurement of near-normal concentrations of erythrocyte protoporphyrin with the hematofluorometer: influence of plasma on "front-surface illumination" assay.
Measurement of near-normal concentrations of erythrocyte protoporphyrin with the hematofluorometer: influence of plasma on "front-surface illumination" assay.
复制标题
用血液荧光计测量接近正常浓度的红细胞原卟啉：血浆对“前表面照明”测定的影响。
作者：
R. Schifman;P. Finley
红细胞中的原卟啉锌在缺铁时增加。由于血荧光仪直接测量全血中的原卟啉锌，因此它可能是一种有用的检测缺铁的筛选仪器。我们用红细胞中正常至略高于正常的原卟啉锌浓度（0.2至2.0 mg/L）来评估其性能，因为这是区分正常和缺铁个体的关键范围。提取法测定的红细胞原卟啉与直接用血荧光仪测定的红细胞原卟啉有极好的相关性（r2 = 0.900）。然而，在这些浓度下，血浆导致血液荧光计读数虚高，高达2.4至89.4%，这是仪器光学设计造成的影响。这种影响可以通过洗去细胞中的血浆或在测量前允许红细胞沉淀到被照射的表面来取代血浆来消除。这种干扰不影响血液荧光仪的灵敏度，但对全血所获得的异常结果应通过更具体的测试来证实，如果使用全血样本，可能会影响实验室间的精度。从样品放置到测量的1分钟延迟使原卟啉锌值降低2.6%至36.9%。我们还描述了冷冻保存对照红细胞的使用，对于浓度为0.96 mg / l的红细胞，CV为2.3%，不受测量时间的影响，并且在三个月内稳定。
Zinc protoporphyrin in erythrocytes increases in iron depletion. Because the hematofluorometer directly measures zinc protoporphyrin in whole blood, it may therefore be a useful screening instrument for detecting iron deficiency. We evaluated its performance with normal to slightly above-normal zinc protoporphyrin concentrations (0.2 to 2.0 mg/L) in erythrocytes, because this is a critical range for differentiating normal and iron-deficient individuals. There was excellent correlation (r2 = 0.900) between erythrocyte protoporphyrin as measured by an extraction procedure and as measured directly with the hematofluorometer. However, at these concentrations, plasma caused hematofluorometer readings to be spuriously high, by 2.4 to 89.4%, an effect due to the instrument's optical design. The effect can be eliminated by washing the cells free of plasma or by allowing erythrocytes to displace plasma by settling to the illuminated surface before the measurement. The interference does not affect the hematofluorometer's sensitivity, but abnormal results obtained for whole blood should be confirmed with more-specific tests, and interlaboratory precision may be influenced if whole-blood samples are used. A 1-min delay from sample placement to measurement decreased zinc protoporphyrin values by 2.6 to 36.9%. We also describe the use of cryopreserved control erythrocytes, for which the CV is 2.3% for a concentration of 0.96 mg per liter of erythrocytes, which are not affected by time of measurement, and which are stable for three months.