Evaluation of fibroblast growth factor 23 as a marker of severity in stable chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), a multi-component disease, is one of the leading causes of morbidity and mortality globally. Considering the drawbacks of current severity markers of COPD, there is a need to find newer alternatives that are easily accessible and provide insight into the underlying pathophysiology of the disease. This study evaluated fibroblast growth factor 23 (FGF23), a pro-inflammatory hormone, as a severity marker for COPD. A total of 54 stable COPD patients were recruited as per the inclusion and exclusion criteria. All participants were subjected to spirometry and body plethysmography with diffusion capacity of lungs for carbon monoxide (DLCO) evaluation. Plasma FGF23 levels were measured for all participants. This study aimed to evaluate FGF23 as a severity indicator of COPD, along with its association with serum phosphate levels, static lung volumes, and DLCO. The mean age of the study population (n=54) was 59±11 years. The majority of study participants had moderate COPD (50%), followed by severe (27.8%), mild (20.4%), and very severe (1.9%). The mean plasma FGF23 value observed was 115±169 pg/mL. A significant negative correlation was observed between FGF23 levels and forced expiratory volume in 1 second (FEV1) (% predicted), demonstrating the diagnostic role of FGF23. The phosphaturic action of FGF23 was validated by a strong negative correlation observed between serum phosphate and plasma FGF23 levels. Receiver-operating characteristic curve analysis of FGF23 showed that cut-off levels of 73.71 pg/mL can be used to distinguish mild to moderate COPD from severe to very severe, with a sensitivity and specificity of 62.5% and 68.4%, respectively. FGF23 levels were found to be significantly increased in individuals with poor lung function and compromised lung volumes. FGF23 levels were negatively correlated with FEV1 (% predicted) and can be used as a potential severity marker. Hence, plasma FGF23 levels showed a promising role as a severity marker of COPD.