Evaluation of subacute kidney injury

AKI: acute kidney injury; NSAID: nonsteroidal anti-inflammatory drug; ACE: angiotensin-converting enzyme; ARB: angiotensin receptor blocker; RBC: red blood cell; RPGN: rapidly progressive glomerulonephritis; ATN: acute tubular necrosis; SPEP: serum protein electrophoresis; UPEP: urine protein electrophoresis; MGUS: monoclonal gammopathy of undetermined significance; GFR: glomerular filtration rate.
* For patients with chronic kidney disease, in whom small fluctuations in creatinine are common, mild injury may be better defined as <50% change in creatinine.
¶ For patients at higher risk for multiple myeloma (ie, age >40 years, and no other obvious cause of reduced GFR), SPEP, UPEP, immunofixation, and serum free light chains are obtained at time of initial evaluation. Some clinicians follow this approach for all adult patients.
Δ Irreversible kidney is suggested by the combination of increased echogenicity and kidney length <10 cm.