Assessment of Renal Function in Chronic Obstructive Pulmonary Disease Using Estimated Glomerular Filtration Rate and Urine Protein Analysis: A Cross-Sectional Study

Background: Chronic obstructive pulmonary disease (COPD) is a major global health problem and is increasingly recognized as a systemic disorder with multiple extrapulmonary manifestations, including renal dysfunction. The coexistence of renal impairment in COPD patients often remains underdiagnosed due to the limitations of conventional markers such as serum creatinine.

Objectives: To assess renal function in patients with COPD using estimated glomerular filtration rate (eGFR) and urine protein analysis, and to evaluate its association with disease severity.

Methods: This hospital-based cross-sectional observational study was conducted over a period of 12 months at a tertiary care center. A total of 150 patients diagnosed with COPD as per Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria were included. Patients with known chronic kidney disease or other conditions affecting renal function were excluded. Detailed clinical evaluation, spirometry, and laboratory investigations including renal function tests and urine protein analysis were performed. eGFR was calculated using the Cockcroft–Gault equation. Statistical analysis was conducted using SPSS version 16.0, with p <0.05 considered statistically significant.

Results: A substantial proportion of patients demonstrated renal impairment, with reduced eGFR and presence of proteinuria. Increasing severity of COPD was significantly associated with higher age, longer duration of illness, elevated serum creatinine levels, and greater prevalence of proteinuria. A progressive decline in eGFR was observed with increasing disease severity. Pearson correlation analysis revealed a strong negative correlation between eGFR and serum creatinine, and moderate negative correlations with age and duration of illness. No statistically significant association was found between COPD severity and comorbidities such as diabetes mellitus and hypertension.

Conclusion: Renal dysfunction is highly prevalent in COPD patients and is strongly associated with disease severity. eGFR and urine protein analysis are more reliable indicators than serum creatinine alone for early detection of renal impairment. Routine renal function assessment should be incorporated into the management of COPD patients to improve outcomes.