Plasma Oxalate Concentration and Patients With CKD.

To the Editor:

In the recent article by Pfau et al., “Assessment of Plasma Oxalate Concentration in Patients With CKD,” they reported a new simple procedure for evaluating plasma oxalate (POx) concentration that enabled the investigation of a large cohort of patients with chronic kidney disease (CKD). They measured POx in 1826 patients with CKD and found stable results; furthermore, they reaffirmed a negative correlation between the estimated glomerular filtration rate and POx.

Recent studies using dual-energy computed tomography angiography have reported that calcium oxalate is one of the main components of coronary artery calcification,, which affects the survival rate of patients with CKD. We are interested in the effects of high POx levels, especially in patients who are undergoing dialysis, and the methods to suppress these effects.

We think this new method may contribute to future research in this area; however, some limitations remain. For instance, they described the correlation between the estimated glomerular filtration rate and POx, but they did not show a regression line in the scatterplot or present a correlation coefficient for the data or its P value. We hoped the authors would present this information, because this figure may be cited widely.

We recognize that this study is a part of an ongoing prospective, large-cohort study. Therefore, we hope that the authors clarify the role of POx not only in CKD progression but also in the progression of coronary artery calcification in the future.