The serum creatinine/cystatin C (Cr/CysC) ratio is beneficial in diagnosing reduction of muscle strength in men with acute exacerbation of chronic obstructive pulmonary disease (AECOPD), suggests recent research. The study by a team of scientists from the Department of Respiratory and Critical Care Medicine, Affiliated Hospital of Guangdong Medical University, China, analysed 72 male patients with AECOPD and 32 with AECOPD to find that Cr/CysC ratio, serum Cr, FEV and  FVC were lower in AECOPD patients than in stable COPD patients. The researchers concluded that the Cr/CysC ratio, which was less than 0.99, seemed a very useful predictor of decreased muscle strength in these patients.