Acute Kidney Injury Neutrophil Gelatinase-Associated Lipocalin Evaluation of Symptomatic Heart Failure Study

Inclusion Criteria: * Subjects must be at least 18 years of age. * Subjects must present to the hospital with one or more signs or symptoms of acute heart failure (AHF). Signs and symptoms include shortness of breath from walking, rales or crackles, galloping heart rhythm, jugular venous distension, trouble breathing at rest or when lying down, waking breathless at night, using more than 2 pillows to sleep, tiring easily, swelling of feet, ankles or legs, frequent coughing, a cough that produces mucous or blood-tinged sputum, or a dry cough when lying flat. * Subjects must receive IV diuretics, or there must be an intent to treat with IV diuretics. * Subjects must be willing and able to comply with all aspects of the protocol. * Subjects must provide signed informed consent. Exclusion Criteria: * Subjects that present with symptoms consistent with acute coronary syndromes (AMI or UA) as the chief cause of the current episode of AHF. * Subjects already on dialysis prior to enrollment or if dialysis initiation is already planned during the current hospital visit. * Subjects that have had any major organ transplant (heart, lung, kidney, or liver). * Subjects that have participated in a drug treatment study within the past 30 days or if they have already been enrolled as a subject in this study. * Women who verbally report being pregnant at the time of screening and anyone belonging to a vulnerable population that is deemed inappropriate for inclusion into the study by the IRB/EC.