# Utility of serum uric acid levels in excluding pulmonary hypertension in severe chronic lung disease: insights from a tertiary care center

## TL;DR

This study shows that normal blood uric acid levels can help rule out pulmonary hypertension in patients with severe chronic lung disease.

## Contribution

The study demonstrates that serum uric acid levels can be used to exclude pulmonary hypertension in patients with chronic lung disease.

## Key findings

- Hyperuricemic patients were more likely to have pulmonary hypertension compared to normouricemic patients.
- Normal serum uric acid levels are a significant predictor for excluding pulmonary hypertension in patients with severe chronic lung diseases.

## Abstract

Hyperuricemia is a known predictor of World Health Organization (WHO) Group 1 pulmonary hypertension (PH) (pulmonary arterial hypertension), but its role in excluding PH secondary to chronic lung diseases (WHO Group 3) remains unclear. We retrospectively analyzed data from 323 patients with severe chronic pulmonary diseases who underwent evaluation for lung transplantation at a tertiary medical center between June 2017 and February 2023. We examined the association between hyperuricemia (serum uric acid > 6 mg/dL or > 0.357 mmol/L) and PH [mean pulmonary arterial pressure (MPAP) > 20 mmHg]. Compared to the normouricemia group (n = 211), hyperuricemic patients (n = 112) were more likely to be younger (P = 0.02), male (P < 0.001), and present with PH (P = 0.001) and severe PH (MPAP > 35 mmHg; P < 0.001). These patients also had a higher body mass index (P = 0.004), plasma N-terminal pro-B-type natriuretic peptide (P < 0.001), serum creatinine (P < 0.001), and C-reactive protein levels (P = 0.03). Significant associations with PH included higher body mass index (P = 0.005), uric acid levels (P < 0.001), total lung capacity (P = 0.02), and residual volume (P = 0.01); shorter 6-min walk test distance (P = 0.005); and lower forced expiratory volume in one second (P = 0.006) and diffusing capacity for carbon monoxide (P < 0.001). Multivariate analysis showed elevated uric acid levels remained significantly associated with PH (OR 1.29, 95% CI 1.05–1.58, P = 0.01). In conclusion, normal serum uric acid levels serve as a significant predictor for excluding pulmonary hypertension in patients with severe chronic lung diseases.