Prognostic implications of plasma myoglobin levels in patients with chronic kidney disease

Purpose: Poor cardiovascular outcomes in chronic kidney disease (CKD) patients have prompted nephrologists to look for biomarkers that may improve risk stratification in this population. The objective of this study was to evaluate plasma myoglobin (Mb) levels according to the CKD stage and to determine whether they are associated with overall, cardiovascular (CV) mortality, CV events, and renal outcomes. Methods: Plasma Mb levels were determined in 140 CKD patients at different stage (mean ± SD age: 67 ± 12; males: 61%) who were prospectively monitored for overall and CV mortality, CV events and CKD progression. Twenty-seven healthy subjects served as controls. Results: Plasma Mb levels were higher in CKD patients than in controls and progressively increased as the glomerular filtration rate fell. Hemoglobin levels, CKD stage, the aortic calcification score and brain natriuretic peptide levels were associated with plasma Mb concentrations. In a multivariate analysis, only CKD stage was associated with Mb levels. During follow up (mean duration: 968 ± 374 days), 44 patients died and 63 had a cardiovascular event. In a crude analysis, plasma Mb >73.8 μg/l predicted overall and cardiovascular mortality and the occurrence of cardiovascular events (p = 0.01, 0.05 and 0.01, respectively). However, this association was lost after adjustment for other prognostic factors for mortality. Plasma Mb was not a significant predictor of the progression of CKD either. Conclusions: Plasma Mb levels were significantly higher in predialysis or dialyzed CKD patients than in healthy controls. However, we could not identify a relevant clinical outcome associated with this elevation. Larger studies are needed to confirm the present results