Urinalysis is helpful for ruling out intrinsic causes of AKI. Patients with intrarenal AKI will have abnormal urine sediment; for example, red blood cell casts are found in glomerulonephritis; granular casts in cases of acute tubular necrosis; and white blood cell casts and eosinophils in acute interstitial nephritis.4
Imaging. The most commonly used imaging for AKI is retroperitoneal ultrasonography of the kidneys, ureters, and bladder, which provides information on the size and shape of the kidneys and can detect stones or masses. It also detects the presence or absence of hydronephrosis, which can occur in postrenal injuries.
Currently, no definitive therapy or pharmacologic agent is approved for AKI; treatment focuses on reversing the cause of the injury. In the immediate aftermath of AKI, it is important to avoid potentially nephrotoxic medications, including NSAIDs. Minimize the use of diuretics and avoid ACEIs and ARB therapy; these can be reintroduced after lab results confirm that the AKI has resolved with a stabilized SCr.
Practice guidelines recommend prompt follow-up at 3 months in most cases of AKI.1 Providers should obtain a metabolic panel and perform a urinalysis to evaluate for chronic kidney disease (CKD), because almost one-third of patients with an AKI episode are newly classified with CKD in the following year.5 Earlier follow-up (< 3 months) is warranted if the patient has a significant comorbidity, such as congestive heart failure.1,2—CS
Christopher Sjoberg, CNN-NP
Idaho Nephrology Associates, Boise
Adjunct Faculty, Boise State University