The objectives of our study were to (1) assess the outcomes resulting from the use of sonography in patients referred to our institution's ultrasound laboratory for an elevated serum creatinine level and (2) determine relevant clinical parameters in these patients to better triage them for sonography. We retrospectively identified and determined outcomes of 60 patients (20 women, 40 men; mean age, 61 years; range, 33 to 100 years) referred for sonographic evaluation because of an increased serum creatinine level (> or = 1.3 mg/dL). Ultrasound findings (hydronephrosis, renal size, and echogenicity) were correlated with clinical outcomes. Twenty-one patients (35%) had hydronephrosis, with 14 of these patients confirmed to be obstructed and five not obstructed. Two were indeterminate for obstruction. Eight of 14 obstructed patients were successfully treated. All obstructed patients had a suggestive history for obstruction with at least one of the following: pelvic mass (n = 9), stone disease (n = 4), or flank pain (n = 1). Only 2 of 44 patients, who were not obstructed, had any of these parameters (statistically significant difference, P < 0.0001). Thirty of the patients, who were not obstructed, had more likely alternative causes for renal failure, with sonography having no effect on patient management. Renal size and echogenicity had little effect on patient management. Sonography was efficacious in guiding management in patients with a suggestive history for obstruction (eg, pelvic mass, stone disease, or flank pain) but not in most patients who had no suggestive history and other more likely causes for renal failure.