Lack of significant renal tubular injury despite acute kidney injury in acute decompensated heart failure.

AIMS: Acute kidney injury (AKI) is a strong predictor of adverse events with an incompletely understood pathophysiology. Neutrophil gelatinase-associated lipocalin (NGAL) is proposed as an early marker of renal tubular injury. Our aim is to determine whether AKI during treatment of acute decompensated heart failure (ADHF) is accompanied by renal tubular injury.

METHODS AND RESULTS: Urinary NGAL (uNGAL) and urinary creatinine (uCreat) levels were measured in 141 consecutive patients hospitalized for ADHF and followed for 180 days for death or re-hospitalization. AKI was defined as a rise in serum creatinine ≥0.3 mg/dl in a 48 h period. Median uNGAL/uCreat levels on Day 1 (baseline) were similar between patients who did and did not develop AKI [22.8 (12.5-106.8) μg/g vs. 20.6 (12.4-52.0) μg/g, P = 0.55]. On Day 2 and beyond, the difference between the AKI and no AKI cohorts increased, but was only significant on Day 3 [36.2 (21.7-131.8) μg/g vs. 29.4 (11.4-54.6) μg/g, P = 0.02]. The area under the receiver operating characteristic curve for Day 2 uNGAL/uCreat (≥ or <32 µg/g) to predict AKI was 0.61. There was no difference in diuretic response between 'uNGAL/uCreat + ' (≥ 27 µg/g) and 'uNGAL/uCreat-' (<27 µg/g) patients. However 'uNGAL/uCreat + ' patients had more adverse events after 180 days (66% vs. 52%, P = 0.02).

CONCLUSIONS: In patients with ADHF who develop AKI following diuretic therapy, a minor rise in uNGAL precedes AKI. However, the degree of renal tubular insult was much lower than that observed in other forms of AKI.