Lipocalina associada à gelatinase neutrofílica: um marcador precoce das modificações agudas na filtração glomerular, após infusão de contraste radiológico para angiografia coronariana

Background: The deterioration of renal function is related to the intensity of injury of the tubules and glomeruli, and the expected reduction in glomerular filtration rate, is belatedly diagnosed through late changes in serum creatinine concentrations. In general, physicians are often faced with the question whether to use drugs and potentially nephrotoxic agents in patients with reduced renal function in cineangiographic procedures. Typically, doctors are faced with the question whether to use drugs and radiographic contrast agents in patients with reduced GFR. Usually, the decision will depend of these situations, and no other additional examination is usually done for the assessment of renal function. Then, the patients are discharged soon after the coronary angiography. However, when the patient returns to medical care, on some occasions, is discovered, too late, worsening renal function. In this situation, an early marker of renal damage would be clinically more useful if it were correlated with posterior serum creatinine concentrations. Objectives: Compare the urinary NGAL concentrations (uNGAL) of patients with and without decreasing in the estimated glomerular filtration rate (eGFR) before and after infusion of radiological contrast used during the cinecoronariography (CINE). We also analyzed the possible correlations between uNGAL and the serum creatinine values measured before and two days after the contrast infusion in patients underwent to the CINE. Methods: Ninety-six patients were studied and, according to the estimated glomerular filtration (eGFR), were formed two groups: group R (n=24) with eGFR below 60 ml/min/1.73 m 2 and group C (n=72) with eGFR above 60 ml/min/1.73 m 2 . The uNGAL and serum creatinine (sCr) levels were measured before and after infusion of the contrast agent. Results: The NGALu concentration before and after contrast infusion was significantly higher in the group R compared to the controls (P < 0.0001). Moreover, the uNGAL and sCr levels before coronary angiography were significantly and positively correlated (r: 0.66; P < 0.0001). Similarly, the NGALu values determined 2 h after angiography were also correlated with the sCr levels measured 2 days after the CINE (r: 0.59; P < 0.0001). Conclusions: The NGALu values were higher in patients with reduced glomerular filtration when compared to controls, and thus, can be considered as a biomarker of GFR in individuals with stable renal function. Moreover, the NGALu concentrations correlated with serum creatinine values obtained 48 hours after hospital discharge, suggesting that it may reflect further evolution of serum creatinine. Therefore, the dosage of NGALu has the expectation to be confirmed as a marker in real-time of GFR. This is especially important in patients with prior reduction of GFR needing to undergo to procedures with potential risk of worsening kidney function, such as coronary angiography, which requires the use of intravascular radiological contrast, potentially nephrotoxic.