Objective: To investigate the correlation between serum cystatin C (Cys-C) and beta-2 (β 2) microglobulin (β 2-MG) levels and renal injury in elderly patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) with a view to detecting renal injury in its early stages.
Methods: A total of 106 patients with AECOPD were enrolled and divided into three groups according to their oxygen partial pressure (PO₂) levels: severe hypoxia group, moderate hypoxia group, and mild hypoxia group. Another 60 healthy subjects were selected as the control group. General clinical data were collected from all the study subjects, along with measurements of arterial blood gas, Cys-C, β 2-MG, serum creatinine (Scr), urea nitrogen (BUN), partial pressure of carbon dioxide (PCO₂), and high-sensitivity C-reactive protein (hs-CRP).
Results: The levels of hs-CRP, Cys-C, β 2-MG, Scr, and BUN were highest in the severe hypoxia group, followed by the moderate hypoxia group, then the mild hypoxia group, and lowest in the control group. The differences between the groups were statistically significant for these indicators (P < 0.05). Apart from in the cases of Scr and BUN, there were no statistically significant differences between the mild group and the control group (P > 0.05). The levels of Cys-C and β 2-MG were positively correlated with the levels of hs-CRP, PCO₂, Scr, and BUN and negatively correlated with PO₂ levels. hs-CRP and PO₂ were high-risk factors influencing Cys-C levels, and β 2-MG was a risk factor influencing Cys-C levels. The level of PO₂ was a high-risk factor influencing β 2-MG levels, and PCO₂ and Cys-C were risk factors influencing β 2-MG levels.
Conclusion: Renal injury was found to be present in patients with AECOPD and worsened with increasing degrees of hypoxia. Hypoxia and inflammation might be risk factors for renal injury in patients with AECOPD, Cys-C and β 2-MG could be sensitive indicators for the early detection of renal injury.
Keywords: cystatin C, β 2 microglobulin, acute exacerbations of chronic obstructive pulmonary disease, early renal injury