Chronic kidney disease
Reduced renal function with elevation of creatinine is chronic (>3 months), although there may be acute on chronic renal disease.
An acutely elevated serum creatinine is diagnostic of AKI and indicative of reduced clearance.
There are no causes of chronically elevated serum creatinine other than reduced glomerular filtration (except for minor elevations in subjects with increased muscle mass and from certain medications).
Creatinine elevation over time provides a chronological perspective and assists in differentiating acute from chronic kidney disease.
Twenty-four-hour urine study for creatinine clearance demonstrates the level of renal function; the use of 131-I iothalamate is the definitive test for this purpose.
Increased muscle mass
Any elevation of creatinine is minor and typically nonacute.
Acutely elevated serum creatinine is diagnostic of AKI.
Minor elevations in creatinine from increased muscle mass may rarely be seen.
Twenty-four-hour urine study for creatinine clearance demonstrates normal renal function.
Drug side effect
Certain medications such as cimetidine or trimethoprim may lead to an elevation of creatinine that is minor and nonacute.
Discontinuing the medication should result in normalizing of the serum creatinine.
Twenty-four-hour urine study for creatinine clearance should demonstrate normal function.
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