Uric Acid : A Mirror to the Lungs in COPD

Abstract

Chronic obstructive pulmonary disease (COPD) is presently the third major cause of death in the world with 80% of deaths due to COPD occurring in countries with low- and middle income. Impaired lung function is associated with high serum uric acid levels due to tissue hypoxia-induced degradation of adenosine, pulmonary arterial hypertension and inflammation-induced damage of lung tissue. This study aims to find out if serum uric acid can be used as an early marker of disease severity in COPD patients by correlating it to spirometry values. Material: The objectives of this study were to estimate serum uric acid levels in patients with COPD and to correlate serum uric acid levels with spirometry values in patients with COPD. This is a cross-sectional study conducted on 80 patients of COPD satisfying inclusion and exclusion criteria admitted in hospitals attached to Bangalore Medical College & Research Institute. All necessary investigations were done, including serum uric acid levels. The patients underwent spirometry and the severity of airflow limitation was classified according to GOLD 2021 guidelines and correlated with the serum uric acid levels. Observation: The age of the patients ranged from 42 to 88 years of which 72 were males and 8 were females with 85% of the total patients being smokers. In this study, out of 80 patients, 7.5%, 16.3%, 38.8% and 37.5% belonged to MMRC grade 0, 1, 2 and 3 respectively. Majority of patients i.e. 37(46.3%) belonged to GOLD stage 2 with 9(11.3%) and 34(42.5%) categorized as GOLD stage 1 and 3 respectively. Mean uric acid level in patients was 3.74, 5.44 and 6.70 mg/dL in patients with post-bronchodilator FEV1 of ≥ 80%, FEV1 50% to < 80% and FEV1 30% to < 50% predicted values respectively while it was 4.43, 6.27 and 6.61 mg/ dL in patients with post-bronchodilator FVC of 100-120%, 80-99% and 60-79% predicted value respectively. Uric acid levels correlated significantly with FEV1 and FVC values (p = 0.00). Significant correlation was also seen between GOLD staging and uric acid (p = 0.00) with uric acid levels of 3.74, 5.43 and 6.70 mg/dL corresponding to GOLD stage 1, 2 and 3 respectively Conclusion: Rising uric acid levels correspond with increasing severity of airflow limitation in patients with COPD. Serum uric acid is a useful, easily available, cost effective marker for predicting disease severity and thereby the prognosis in patients with COPD.