Plasma neutrophil gelatinase-associated lipocalin (NGAL) as an early predictive marker of contrast-induced nephropathy in hospitalized patients undergoing computed tomography.

BACKGROUND: Contrast-induced nephropathy (CIN) is a common cause of hospital-acquired acute kidney injury (AKI). Neutrophil gelatinase-associated lipocalin (NGAL) represents a promising biomarker for AKI. Its role in the early diagnosis of CIN has already been examined in adults and children undergoing coronary angiography. This study was designed to prospectively evaluate plasma NGAL compared with serum creatinine (SCr) for early CIN detection among hospitalized patients undergoing contrast-enhanced computed tomography (CT).

METHODS: We prospectively enrolled consecutive hospitalized patients undergoing elective CT with intravenous (IV), low-osmolar contrast administration. Patients with pre-procedure SCr >150 μmol/L (1.7 mg/dL), congestive heart failure, haemodynamic instability, sepsis, or urinary tract infection were excluded. Plasma NGAL was measured using the standardized Triage(®) NGAL test (Biosite Incorporated, San Diego, CA, USA) at baseline and 6 h post-procedure. SCr, blood urea nitrogen (BUN), albumin and sodium (Na) were measured and eGFR MDRD4 was calculated at the same intervals, as well as at 24 and 48 h post-procedure. CIN was defined as an increase in SCr of >25% or >44 μmol/L (0.5 mg/dL) from baseline within 48 h post-procedure, in the absence of other obvious causes.

RESULTS: Forty-seven patients, male/female 27/20, median age 68 (31-88) years, 16/47 diabetics, with baseline SCr 91.94 ± 20.33 μmol/L (1.04 ± 0.23 mg/dL) and eGFR MDRD4 68.40 ± 18.22 mL/min/1.73 m(2) were enrolled. A contrast volume of 120 mL (range 100-150 mL) was administered. CIN was found in four subjects (8.51%), but detection by SCr was only possible 24 h in 1 and 48 h post-procedure in three. In contrast, significant elevation of plasma NGAL was found at 6 h post-procedure in those with versus those without CIN (779.25 ± 361.49 versus 82.30 ± 40.64 ng/mL, P < 0.001). Using a cutoff value of 200 ng/mL, sensitivity, specificity and area under the receiver-operating characteristic (ROC) curve of 6-h plasma NGAL for CIN prediction were excellent (100, 100 and 1.00%, respectively). Subjects with CIN did not differ in baseline demographics, renal function and diabetes status compared with those without CIN. No differences in any variable were noted between diabetics and non-diabetics. Plasma NGAL at 6 h (R (2) = 0.24, P < 0.001) was found to be an independent predictor of CIN.

CONCLUSIONS: Plasma NGAL 6 h after contrast administration measured by the rapid, point-of-care Triage(®) NGAL test appears to be a useful biomarker in the early prediction of CIN among hospitalized patients undergoing elective contrast-enhanced CT. However, the small sample size and the very small number of CIN events are important limitations. In any case, according to our evaluation, CIN incidence in this well-controlled population underlines the importance of early detection by an adequate and simple procedure such as the 6-h plasma NGAL test.