Combined use of urinary neutrophil gelatinase-associated lipocalin (uNGAL) and albumin as markers of early cardiac damage in primary hypertension

Background: Neutrophil Gelatinase-Associated Lipocalin (NGAL) is an early and specific marker of acute kidney dysfunction. Recent evidences suggest that NGAL may also be involved in chronic vascular remodeling during the development of atherosclerosis. Albuminuria, a powerful predictor of cardiovascular events, is thought to reflect widespread subclinical vascular abnormalities. We investigated the relationship between urinary NGAL (uNGAL), albuminuria and left ventricular mass (LVM) in patients with primary hypertension. Methods: A total of 120 untreated, non diabetic patients with primary hypertension (mean age 47 ± 9. years) were studied. uNGAL was measured by a chemiluminescent microparticle method, optimized on a fully automated analytical platform (ARCHITECT, Abbott Diagnostics Inc, Rome, IT). Albuminuria was measured by immunonephelometry on an Immage Immunochemistry System (Beckman Coulter, Inc., Fullerton, California, USA) and expressed as albumin/creatinine ratio (ACR). LVM was assessed by echocardiography and indexed to body surface area (LVM/BSA). Results: No significant correlation was found between uNGAL and ACR; however, both variables were directly related to clinic systolic blood pressure (rho = 0.241, p = 0.0085 and rho = 0.248, p = 0.0068 respectively), left ventricular relative wall thickness (rho = 0.251, p = 0.0156 and rho = 0.263, p = 0.0013 respectively), and LVM/BSA (rho = 0.285, p = 0.0062 and rho = 0.213, p = 0.0410 respectively). The uNGAL and ACR simultaneous increase above their respective median values was associated with higher LVM/BSA values (p = 0.0109) and with a higher prevalence of left ventricular hypertrophy (LVH) (p = 0.0017). Furthermore, logistic regression analysis showed that the risk of presenting LVH increased more than 4-fold when uNGAL and ACR were both above the median value, even after adjustment for age, gender and blood pressure values. Conclusions: The simultaneous increase in uNGAL and ACR excretion is significantly associated with the increase of LVM in low risk patients with primary hypertension. This association is clinically significant for the early assessment of cardiac damage in hypertension.