Balga I, Solenthaler M, Furlan M
Central Hematology Laboratory, University Hospital, Inselspital, Bern, Switzerland.
Blood Cells Mol Dis. 2000 Feb;26(1):25-31; discussion 32-6. doi: 10.1006/bcmd.2000.0272.
The whole-body volume of red blood cells must be known for correct diagnosis of polycythemia vera. Since the venous hematocrit may not correctly reflect the absolute amount of red blood cells, the red cell mass (RCM) is usually determined by radioisotope labeling of red blood cells according to recommendations of the International Committee for Standardization in Haematology. We examined whether the radioisotope labeling procedure can be replaced by a simple calculation of RCM from the values of venous blood hematocrit and plasma volume, using an empirical factor (Ratio f) equal to the mean ratio between whole-body and venous hematocrit. A retrospective study was performed of 264 cases in which the RCM was assayed using (51)Cr or (99m)Tc for red cell labeling, and (125)I-labeled albumin was used for estimation of plasma volume. The results showed wide scattering of Ratio f (mean value 0.911; range from 0.76 to 1.15) that was responsible for substantial differences between the measured and calculated values of RCM. We also tested whether the calculated RCM may be used as an appropriate marker for polycythemia vera according to recommendations of the International Council for Standardization in Haematology. Our data showed that 146 patients had measured RCM values more than 25% above the mean normal predicted value. Using the calculated RCM, 17 of these patients would be lost from the polycythemia vera group, whereas 29 subjects with measured RCM levels equal to or lower than 125% of predicted values would incorrectly meet the RCM criterion for polycythemia vera. Thus, a total of 46 patients would be misclassified by using the calculated RCM. We conclude that the radioisotope labeling of red blood cells remains mandatory for correct determination of the whole-body red cell volume.
为准确诊断真性红细胞增多症，必须了解红细胞的全身容积。由于静脉血细胞比容可能无法正确反映红细胞的绝对数量，通常根据国际血液学标准化委员会的建议，通过对红细胞进行放射性同位素标记来测定红细胞容积（RCM）。我们研究了是否可以用一个经验因子（比率f，等于全身与静脉血细胞比容的平均比率），根据静脉血细胞比容和血浆容积的值来简单计算RCM，从而取代放射性同位素标记程序。我们对264例病例进行了回顾性研究，这些病例中使用（51）Cr或（99m）Tc标记红细胞来测定RCM，并使用（125）I标记的白蛋白来估计血浆容积。结果显示比率f的离散度较大（平均值为0.911；范围为0.76至1.15），这导致了RCM测量值与计算值之间存在显著差异。我们还根据国际血液学标准化委员会的建议，测试了计算得出的RCM是否可作为真性红细胞增多症的合适标志物。我们的数据显示，146例患者的测量RCM值比正常预测平均值高出25%以上。使用计算得出的RCM，这些患者中有17例将被排除在真性红细胞增多症组之外，而另外29例测量RCM水平等于或低于预测值125%的患者将错误地符合真性红细胞增多症的RCM标准。因此，使用计算得出的RCM会导致总共46例患者被错误分类。我们得出结论，为正确测定全身红细胞容积，对红细胞进行放射性同位素标记仍然是必不可少的。
