Predictors and consequences of subclinical renal impairment in patients with vascular disease

Abstract

Abstract Background Estimated glomerular filtration rate (eGFR) is the most widely used biomarker of kidney function. However, measurement of biomarkers more sensitive than eGFR may be required to detect subtle renal changes and to identify additional predictors and consequences of kidney injury. In the present study, we aimed to identify predictors and consequences of subclinical renal impairment, as reflected by the levels of neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C. Methods A cross-sectional study was performed in 71 consecutive patients with vascular disease. Demographic and anthropometric data, medical history, and ongoing drug therapy were recorded for each patient. Total blood count, hemoglobin, plasma potassium, glucose, cholesterol, triglycerides, total protein, albumin, serum creatinine, uric acid, NGAL and cystatin C levels, and eGFR were evaluated in all patients. Potential predictors and consequences of increased NGAL and cystatin C levels were assessed. Results History of hypertension, diabetes, and ongoing diuretic therapy were the only independent predictors of decreased eGFR (all p < 0.01). Meanwhile, increased white blood cell count and diuretic usage were independently associated with higher NGAL and cystatin C levels, respectively, and increased uric acid levels were independently associated with higher levels of both biomarkers of kidney injury (all p < 0.05). At their turn, increased NGAL and cystatin C levels were independently associated with lower albumin and HDL-C levels, and increased cystatin C levels were also associated with higher serum potassium (all p < 0.05). Conclusions In this study, eGFR values were independently associated with widely known risk factors for impaired renal function. Meanwhile, NGAL and cystatin C evaluation identified more subtle hematologic and biochemical changes related to subclinical kidney injury. These data reinforce the role of NGAL and cystatin C as not only biomarkers of subclinical kidney injury, but also as predictors of subclinical kidney injury-related abnormalities.