Differentials

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Reduced renal function with elevation of creatinine is chronic (>3 months), although there may be acute on chronic renal disease.

INVESTIGATIONS

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.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Any elevation of creatinine is minor and typically nonacute.

INVESTIGATIONS

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.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Certain medications such as cimetidine or trimethoprim may lead to an elevation of creatinine that is minor and nonacute.

INVESTIGATIONS

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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