Abstract: Objective To investigate the relationship between blood lead levels（BLLs） and hematological parameters in children with severe lead poisoning,so as to explore the effect of high blood lead level on hematological parameters at high altitudes. Methods A total of 591 patients with lead poisoning in a hospital in Sichuan from July 2021 to May 2022 were selected. 475 children with healthy physical examination were selected as the control group. The leukocyte count（WBC）,red blood cell count（RBC）,hemoglobin（HGB）,hematocrit（HCT）,mean corpuscular volume（MCV）,mean corpuscular hemoglobin（MCH）,mean corpuscular hemoglobin concentration（MCHC）,width of red blood cell distribution（RDW）,platelet count（PLT）and blood lead levels（BLLs）were collected.The correlation between blood lead level and hematological parameters was analyzed,to assess the effect of high blood lead levels on hematological parameters. Results The RBC,HGB,HCT,MCV and MCH of the lead poisoning group were significantly lower than those of the control group,while the RDW of the lead poisoning group was significantly higher than that of the control group（P<0.05）. The BLLs of the lead poisoning group was negatively correlated with RBC（r_s=-0.10,P=0.012）,HGB（r_s=-0.24,P<0.001）,HCT（r_s=-0.22,P<0.001）,MCV（r_s=-0.20,P=0.002）,MCHC（r_s=-0.18,P<0.001）and MCH（r_s=-0.23,P<0.001）,and positively correlated with RDW（r_s=0.28,P<0.001）. Logistic regression analyses showed that BLLs were significantly associated with decreased HGB,HCT,MCV,MCH,MCHC and increased RDW after adjusting for potential confounders. The children with BLLs ≥700 μg/L were 1.34,0.91,0.87,1.61 and 1.25 times more likely to achieve decreased HGB,HCT,MCV,MCH and MCHC,respectively,compared to those with BLLs < 700 μg/L. Compared with children with BLLs<700 μg/L,those with BLLs≥700 μg/L were 1.47 times more likely to show increased RDW. The individuals with BLLs of the highest quartile were 2.16,1.03,and 1.81 times more likely to exhibit decreased HGB,HCT and MCH,respectively,than the children with BLLs of the lowest quartile. Compared with children with BLLs of the lowest quartile,those with BLLs of the highest quartile were 1.47 times more likely to show increased RDW. Conclusions High blood lead levels in children with severe lead poisoning at high altitudes have affected the hematopoietic function of the blood system,resulted in a decrease in the oxygen-carrying capacity of red blood cells,which in turn affected children's growth and development and quality of life.

Key words: Lead poisoning, Blood lead level, Hematological parameters, High attitude