A J-shaped relationship between hemoglobin levels and chronic kidney disease

To evaluate the connection between hemoglobin and chronic kidney disease in the adult population at high altitudes. 380 people who were at least 18 years old were invited to participate in this cross-sectional study, and they underwent interviews and examination for albuminuria, hematuria, estimated glomerular filtration rate (eGFR), hemoglobin, and several other essential variables from April 2021 to May 2021. The total prevalence of chronic kidney disease was 15%. During logistic regression analysis, we found that participants with elevated hemoglobin per 10 g/L had a 27% greater risk of chronic kidney disease (adjusted odds ratio (OR), 1.27; 95% confidence interval (CI), 1.09-1.48), and high-altitude polycythemia significantly increased the chronic kidney disease risk compared to the group without high-altitude polycythemia (OR, 2.44; 95% CI, 1.20-4.97, p = 0.019). Our observations further revealed a distinct J-shaped correlation between hemoglobin levels and chronic kidney disease, which had a threshold of approximately 213 g/L. The effect sizes and confidence intervals were 0.999 (0.979-1.018) below the threshold and 1.089 (1.029-1.154) above the threshold. Hemoglobin levels were significantly associated with chronic kidney disease in Tibetans. When the hemoglobin levels exceeded a certain value (approximately213 g/L), the risk of chronic kidney disease was significantly increased. High-altitude polycythemia was a risk factor for chronic kidney disease.