Acute exacerbation of COPD tied to renal injury which may worsen with increasing degrees of hypoxia

In the research, inflammation and hypoxia were shown to be risk factors for renal injury in AECOPD patients, "β 2-MG and Cys-C could be sensitive indicators for early diagnosis of renal injury," the researchers wrote in their study that apeared in the International Journal of Chronic Obstructive Pulmonary Disease.

Dong Zhang, Department of Internal Medicine, The Second Hospital of Beijing, Beijing, People's Republic of China, and colleagues conducted the study to examine the correlation between the levels of beta-2 (β 2) microglobulin (β 2-MG) and serum cystatin C (Cys-C) and renal injury in older patients with acute exacerbations of AECOPD with a view for early stage detection of renal damage.

The researchers enrolled a total of 106 AECOPD patients. They were divided into three groups per their oxygen partial pressure (PO2) levels: moderate hypoxia group, severe hypoxia group, and mild hypoxia group. Sixty healthy subjects were considered as the control group.

Collection of clinical data was done from all study subjects, along with measurements of serum creatinine (Scr), Cys-C, β 2-MG, partial pressure of carbon dioxide (PCO2), serum creatinine (Scr), and high-sensitivity C-reactive protein (hs-CRP).

Based on the study, the researchers reported the following findings:

• Cys-C, hs-CRP, β 2-MG, Scr, and BUN levels were highest in the severe hypoxia group, followed by the moderate hypoxia group, then the mild hypoxia, and lowest in the control group.
• The differences between the groups were statistically significant for these indicators.
• Apart from in the cases of Scr and BUN, there were no statistically significant differences between the mild group and the control group.
• Cys-C and β 2-MG levels were positively correlated with the stories 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.

"In patients with COPD, a renal injury was observed, and the extent of renal injury in older patients in acute exacerbation phase might increase with hypoxia degree," the researchers wrote. "Levels of Cys-C and β2-MG versus Scr and BUN showed changes at the early stage of renal injury so that they may be sensitive indicators for the early diagnosis of renal injury."

"hs-CRP and PO2 might be high-risk factors for both β2-MG and Cys-C, indicating that release of inflammatory factors and hypoxia might be risk factors for renal injury in AECOPD patients."

"With advances in the knowledge of β2-MG and Cys-C in renal injury in AECOPD patients, the early diagnosis of renal injury and effective control of risk factors could be facilitated, potentially improving long-term survival of AECOPD patients," they conclude.

Reference:

Zhang D. Correlation Analysis of Early Renal Injury in Elderly Patients with Acute Exacerbations of Chronic Obstructive Pulmonary Disease. Int J Chron Obstruct Pulmon Dis. 2022;17:2109-2115. https://doi.org/10.2147/COPD.S377847