d'Onofrio G, Zini G, Ricerca B M, Mancini S, Mango G
Hematology Service, Catholic University of the Sacred Heart, Rome, Italy.
Arch Pathol Lab Med. 1992 Jan;116(1):84-9.
Some routine red blood cell (RBC) measurements and indexes (count, mean volume, volume dispersion, and mean hemoglobin [HGB] concentration) can be used to differentiate iron deficiency from heterozygous beta-thalassemia. A number of formulas that incorporate two or more of these measurements have been described to amplify such differences. The H1 hematology analyzer directly measures volume and HGB concentration of individual RBCs. We have assessed the diagnostic usefulness of conventional and new RBC measurements provided by the H1 on a learning data set that comprised 119 patients with iron deficiency and 172 patients with beta-thalassemia trait, both untreated and uncomplicated. The most striking finding was the inverse behavior of percentages of microcytes (volume, less than 60 fL) and hypochromic RBCs (HGB concentration, less than 280 g/L) in the two conditions. In 162 of 172 patients with beta-thalassemia trait, the percentage of microcytes (mean, 33.1%; central 95th percentile range, 9.2% to 54.5%) was higher than the percentage of hypochromic RBCs (mean, 13.9%; central 95th percentile range, 1.7% to 24.7%). In 105 of 119 patients with iron deficiency, on the contrary, the percentage of hypochromic cells (mean, 34.6%; central 95th percentile range, 9.7% to 73.1%) was higher than the percentage of microcytes (mean, 12.8%; central 95th percentile range, 1.7% to 29.6%). The ratio between the percentage of microcytes and the percentage of hypochromic cells provided by the H1 (microcytic-hypochromic ratio) was useful in differentiating the two types of microcytic anemia: with the use of a discriminant value of 0.9, the discriminant efficiency of the microcytic-hypochromic ratio was 92.4% (95% confidence interval, 88.8% to 95.2%), higher than that of the five previously described discriminant formulas and simple RBC measurements. When assessed on a test data set that comprised 149 unselected cases of microcytic anemia, a microcytic-hypochromic ratio lower than 0.9 demonstrated high sensitivity (94.0%), specificity (92.3%), and predictive value (94.0%) for the presence of iron-deficient erythropoiesis in patients with isolated iron deficiency, polycythemia vera treated by phlebotomy, and iron deficiency complicating heterozygous thalassemia. In conclusion, our results showed that iron-deficient erythropoiesis is characterized by the production of RBCs with a severely decreased HGB concentration, while microcytes of beta-thalassemia trait are generally smaller, with a more preserved HGB concentration. Such properties, as assessed by the H1 hematology analyzer, are very useful in distinguishing these two common types of microcytic anemia.
一些常规红细胞（RBC）测量值和指标（计数、平均体积、体积离散度和平均血红蛋白[HGB]浓度）可用于区分缺铁性贫血和杂合子β地中海贫血。已描述了一些纳入这些测量值中两项或更多项的公式，以放大此类差异。H1血液分析仪可直接测量单个红细胞的体积和HGB浓度。我们在一个包含119例缺铁患者和172例β地中海贫血特征患者（均未经治疗且无并发症）的学习数据集上，评估了H1提供的常规和新的RBC测量值的诊断效用。最显著的发现是，在这两种情况下，小红细胞（体积小于60 fL）和低色素性红细胞（HGB浓度小于280 g/L）的百分比呈现相反的表现。在172例β地中海贫血特征患者中的162例中，小红细胞的百分比（平均为33.1%；第95百分位数中心范围为9.2%至54.5%）高于低色素性红细胞的百分比（平均为13.9%；第95百分位数中心范围为1.7%至24.7%）。相反，在119例缺铁患者中的105例中，低色素性细胞的百分比（平均为34.6%；第95百分位数中心范围为9.7%至73.1%）高于小红细胞的百分比（平均为12.8%；第95百分位数中心范围为1.7%至29.6%）。H1提供的小红细胞与低色素性细胞百分比之间的比值（小红细胞 - 低色素性比值）有助于区分这两种类型的小细胞性贫血：使用判别值0.9时，小红细胞 - 低色素性比值的判别效率为92.4%（95%置信区间为88.8%至95.2%），高于之前描述的五个判别公式和简单RBC测量值。当在一个包含149例未选择的小细胞性贫血病例的测试数据集上进行评估时，小红细胞 - 低色素性比值低于0.9对于单纯缺铁、放血治疗的真性红细胞增多症以及杂合子地中海贫血合并缺铁患者中缺铁性红细胞生成的存在具有高敏感性（94.0%）、特异性（92.3%）和预测价值（94.0%）。总之，我们的结果表明，缺铁性红细胞生成的特征是产生HGB浓度严重降低的红细胞，而β地中海贫血特征的小红细胞通常较小，HGB浓度保存较好。通过H1血液分析仪评估的这些特性对于区分这两种常见的小细胞性贫血非常有用。
