Traditional and Novel Tools for Diagnosis of Acute Kidney Injury
Diagnosis of acute kidney injury (AKI) is traditionally based on changes of serum creatinine (SCr) over time or compared to baseline. Oliguria, even without elevation in SCr, carries a prognostic significance. Including urine output in the definition of A
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Fadi A. Tohme and John A. Kellum
Case Presentation A 58-year-old male with unknown past medical history was admitted to the intensive care unit after he had a witnessed seizure in a parking lot. When paramedics arrived, his blood pressure was 213/115 mmHg. He was unresponsive. CT scan of the head without IV contrast showed a large right parietal lobe hemorrhage with mild midline shift. Laboratory exam revealed a WBC count of 13.2 × 109/L, Hemoglobin 10.2 g/dL, Platelets 178,000 × 106/L. Serum creatinine was 1.8 mg/ dL and blood urea nitrogen (BUN) 41 mg/ dL. Baseline serum creatinine was unknown. BMI was 27.3. An indwelling urinary catheter was placed and yielded 50 cc of urine. He was intubated and treated with calcium channel blockers, anti-seizure medications and intravenous fluid resuscitation. Twelve hours after admission, he had produced 150 cc of urine, and his repeat labs showed a serum creatinine of 2.2 mg/dL and a BUN of 47 mg/dL. A renal
F.A. Tohme Renal & Electrolyte Division, University of Pittsburgh Medical Center, Pittsburgh, PA, USA J.A. Kellum (*) Critical Care Research, Center for Critical Care Nephrology, Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, USA e-mail: [email protected]; [email protected]
u ltrasound showed normal sized kidneys, with increase in echogenicity of the renal cortex compared to the liver parenchyma, but no hydronephrosis. Urinalysis and urine microscopy revealed 1+ protein, no blood or cellular casts. Question What establishes the diagnosis of Acute Kidney Injury in this case? Answer Increase in serum creatinine and oliguria. Criteria for diagnosis of acute kidney injury (AKI) include a 1.5 fold increase in serum creatinine compared to baseline (within the prior 7 days), an absolute increase in serum creatinine (SCr) by 0.3 mg/dL (26.5 μmol/L) or more (within 48 h) or a decrease in urine output to less than 0.5 cc/Kg/h for 6–12 h. In this case, SCr was elevated on admission (1.8 mg/dL), but it was not clear whether this represented acute kidney injury or Chronic Kidney Disease (CKD). Low urine output through the indwelling urinary catheter initially and over the next few hours after admission was an important first clue to the diagnosis of AKI. Subsequent increase in SCr by ≥0.3 mg/ dL (from 1.8 to 2.2 mg/dL) confirmed the diagnosis. When baseline creatinine is not known, both renal ultrasonography and urine sediment examination can provide useful clues on the acuity of kidney injury. In this case, the increase in renal cortex echogenicity and presence of mild proteinuria suggested the presence of some
© Springer International Publishing Switzerland 2017 R.C. Hyzy (ed.), Evidence-Based Critical Care, DOI 10.1007/978-3-319-43341-7_42
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degree of chronic kidney dysfunction prior to admission. Therefore, this patient probably had acute kidney injury superimposed on CKD.
Principles of Management Serum Creatinine and Urine Output Despite having several limitations, changes in serum creatinine and urine output
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