# Albuminuria as a non-invasive biomarker of endothelial dysfunction in patients with COPD

## TL;DR

This study shows that albuminuria, a sign of blood vessel problems, is more common in COPD patients and linked to worse health outcomes.

## Contribution

The study identifies albuminuria as a potential non-invasive biomarker for endothelial dysfunction in COPD patients.

## Key findings

- COPD patients had higher albuminuria levels and more frequent exacerbations compared to non-COPD smokers.
- Low oxygen saturation (SpO2) was the strongest independent predictor of albuminuria in COPD patients.
- Albuminuria was negatively associated with blood vessel function (FMD) and positively with comorbidities and high blood sugar.

## Abstract

Endothelial dysfunction (ED) plays a significant role in the pathogenesis of chronic obstructive pulmonary disease (COPD). While albuminuria is currently recognized as a biomarker of generalized ED, data on the evaluation of albuminuria among COPD patients and its association with disease outcome measures are still limited. Thus, the aim of this study was to assess albuminuria among a group of COPD patients and investigate its relationship with clinical and physiological parameters. Sixty adult patients with COPD and forty non-COPD adult smokers were included in this cross-sectional study. All participants were assessed for anthropometric parameters, oxygen saturation (SpO2), spirometry test, 6-minute walk test, flow-mediated dilation (FMD) of the brachial artery, routine laboratory measurements, and urinary albumin-to-creatinine ratio (UACR). Patients with COPD had higher levels of UACR (mg/g) and a greater prevalence of albuminuria than non-COPD smokers. COPD patients with albuminuria had higher body mass index (BMI), more frequent exacerbations, lower SpO2, lower FMD, and higher fasting plasma glucose than patients without albuminuria. UACR in COPD patients was associated negatively with FMD and SpO2 and positively with the number of comorbidities and fasting plasma glucose. The main predictors of albuminuria in COPD patients were high BMI, low SpO2, and high fasting plasma glucose. The only independent predictor of albuminuria was the presence of low SpO2. Given the significant association with FMD, the gold standard measure of ED, we suggest that the measurement of UACR could be routinely utilized for assessing ED in COPD patients, particularly those with low oxygen saturation.