LAUSR

We read with interest the article by Yildiz et al entitled “Association of serum osmolarity with contrast-induced nephropathy (CIN) in patients with ST-segment elevation myocardial infarction.” The authors identified serum hyperosmolarity as a risk factor for CIN development in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (pPCI). Serum osmolarity plays an important role in extracellular and intracellular water distribution and mainly depends on the concentrations of sodium (Naþ), potassium (Kþ), chlorine (Cl), glucose, and urea. Perturbation of osmolarity is strongly associated with fluid-electrolyte imbalances, such as dehydration and hypernatremia, leading to adverse consequences such as increased risk of cardiovascular, cerebral, respiratory and renal disorders, and mortality. The Yildiz et al study extended this observation to cardiovascular diseases, especially STEMI undergoing pPCI. Contrast-induced nephropathy represents a significant adverse event of contrast medium administration, leading to worse clinical outcomes despite successful coronary revascularization. The mechanisms causing CIN remain poorly understood. Probably several mechanisms are involved, revealing a complex multifactorial physiopathology with a interindividual variability. Preexisting renal impairment, metabolic syndrome, congestive heart failure, peripheral artery disease, older age, anemia, diabetes, and the use of large contrast medium volumes may be risk factors for the development of CIN. Many available biomarkers such as homocysteine, procalcitonin, high-sensitivity C-reactive protein, N-terminal pro-brain natriuretic peptide, red cell distribution width, neutrophil to lymphocyte ratio, platelet to lymphocyte ratio, monocyte to highdensity lipoprotein ratio, and fibrinogen to albumin ratio (FAR) have been shown to predict CIN development. In the study by Yildiz et al, serum osmolarity, hemoglobin, contrast media volume, creatinine on admission, basal SYNergy between PCI with TAXus and cardiac surgery II score, and left ventricular ejection fraction were found to be independent predictors of CIN. However, serum osmolarity only had a modest predictive accuracy for CIN in this analysis. Risk estimation for CIN should not be based solely on serum osmolarity; all relevant predictors of CIN should be considered during clinical decision-making. To improve the accuracy for predicting CIN, further studies should be focused on the combined information of several biomarkers and related scores.