Impaired and worsening renal function are established risk markers in heart failure . Data on the prognostic value of NGAL is mixed, with many —but not all —studies in both chronic and AHF reporting prognostic value, though correction for potential confounders varies greatly. Givertz et al. previously reported on the prognostic value of various renal markers in PROTECT, concluding that creatinine change and baseline BUN were strong predictors of outcome . Additionally, our analyses show that NGAL modulates the risk of outcomes associated with creatinine change, conferring a greater relative risk to patients with higher NGAL levels with a creatinine increase, but not to patients without. This effect is independent of baseline creatinine. Furthermore, a large increase in NGAL during admission conferred an additional risk of death (only in patients with WRF). Thus, while plasma NGAL levels appear to largely reflect GFR (and thus creatinine), they do have some incremental value for assessing the risk associated with WRF, and could help discriminate between higher and lower risk WRF.