目的 分析对比老年巨幼细胞性贫血（MA）和骨髓增生异常综合征（MDS）患者的实验室指标特点，并探讨其临床意义。方法 对121例老年MA患者和81例老年MDS患者的外周血像、血清造血原料水平、总胆红素、间接胆红素、同型半胱氨酸等实验室指标进行回顾分析。结果 MA组的平均红细胞体积、平均血红蛋白含量、平均血红蛋白浓度、胆红素、同型半胱氨酸水平明显高于MDS组（P<0.05）；MA组的白细胞计数、红细胞计数、维生素B12、铁蛋白明显低于MDS组（P<0.05）。两组间血红蛋白、血小板计数、红细胞体积分布宽度、叶酸水平差异无统计学意义（P>0.05）。结论 对于怀疑MA或MDS的老年患者，平均红细胞体积、平均血红蛋白含量、平均血红蛋白浓度、总胆红素、间接胆红素、铁蛋白对于MA和MDS的鉴别诊断价值小，而叶酸、维生素B12联合同型半胱氨酸水平检测可用于两者鉴别，对于基层医院无条件检测叶酸、维生素B12的情况下，同型半胱氨酸水平升高提示叶酸和维生素B12缺乏，同型半胱氨酸水平升高为MA与MDS 的鉴别诊断提供重要参考依据。

Objective To investigate the clinical values of folic acid, cobalamin and homocysteine in the differential diagnosis of megaloblastic anemia (MA) and myelodysplastic syndrome (MDS of old Chinese patients. Methods 121 patients with MA and 81 patients with MDS were included in this retrospective study. Peripheral hemogram, serum level of hematopoietic material, total bilirubin and indirect bilirubin and serum level of homocysteine were compared. Results Mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, bilirubin and homocysteine level of the MA group were significantly higher than those of the MDS group (P<0.05). White blood cell count, red blood cell count, serum level of vitamin B12 and serum ferritin of the MA group were significantly lower than those of the MDS group (P<0.05). Hemoglobin, platelet count, red cell distribution width and serum level of folic acid were not significantly different between the MDS group and the MA group (P>0.05). Conclusion For patients suspected of suffering from MA or MDS, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, serum level of total/indirect bilirubin, serum ferritin are not valuable for the differential diagnosis of macrocytic anemia of old Chinese patients. Serum folic acid, vitamin B12 and homocysteine are valuable. In institutions where folic and/or vitamin B12 test is unavailable, high level of homocysteine indicates folic and/or vitamin B12 insufficiency, which indicates megaloblastic anemia is more likely the diagnosis.