The biomarker of kidney disease can also be a marker of COPD

According to a new study published online in the American Thoracic Society, a commonly used renal disease biomarker could also indicate lung problems, particularly COPD, or chronic obstructive pulmonary disease. American Journal of Respiratory and Critical Care Medicine.

In "Albuminuria, Decline in Pulmonary Function and Risk of COPD Incident: NHLBI Grouped Cohort Study", Elizabeth C. Oelsner, MD, MPH and coauthors report a link between albuminuria, albumin in urine and COPD. The researchers conducted their study by aggregating information from 31,877 participants (mean age: 60 years) from six cohort studies funded primarily by the National Heart, Lung and Blood Institute.

Albuminuria indicates a lesion of the single layer of cells lining the blood vessels, called the endothelium, in the kidney. Previous studies have shown that this damage is associated with microvascular (small vessel) dysfunction throughout the body, including the lungs. However, according to the authors of this study, no large-scale prospective study has verified whether albuminuria is associated with the development of COPD.

"The pulmonary microvascular system is essential for gas exchange and is known to be altered in patients with COPD, particularly those with emphysema," said Dr. Oelsner, an assistant professor of medicine at the University of Toronto. Columbia University. "We wanted to test whether albuminuria, a noninvasive and commonly used clinical test, could serve as a marker of increased risk of developing chronic lower respiratory diseases, such as COPD and asthma."

The researchers excluded participants who were diagnosed with COPD or asthma when they enrolled in studies. Participants were followed for changes in lung function over a median of 6 years and for respiratory hospitalizations and mortality over a median of 15 years.

The study found for each increase in the standard deviation of albuminuria was:

• 15% increase in those who have developed moderate to severe COPD;
• 26% increase in hospitalizations and deaths due to COPD; and
• 3% decrease in FEV1 (amount of air that can be forcibly exhaled in one second) and 11% decrease in FEV1 and FVC ratio (the total amount of air that can be exhaled after breathing the deepest possible)). FEV1 and FEV1 / FVC are important measures of lung function.

The researchers found that these associations remained significant even after taking into account smoking history, diabetes, hypertension, and cardiovascular disease. Interestingly, although smoking is known to cause both endothelial damage and COPD, the results were similar for non-smokers. The study did not reveal any significant association between albuminuria and asthma.

The authors stated that their findings suggest that endothelial lesions in the lungs can play an important role in the development and progression of COPD. They added that the mechanisms behind these lesions and microvascular dysfunction could be promising targets for new treatments designed to prevent or treat COPD.

Dr. Oelsner noted that a clinical trial is currently underway to determine whether angiotensin II receptor blockers (ARBs), which prevent the progression of renal failure, can also slow the onset of progression of emphysema.

"Our study helps explain why patients with COPD often have a constellation of vascular problems, including heart and kidney disease," said Dr. Oelsner. "This makes it all the more important that clinicians encourage avoidance of exposures such as smoking and the treatment of diseases such as hypertension and diabetes that cause endothelial dysfunction."

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