Creatinine, Blood

Creatinine, Blood is a topic covered in the Davis's Lab & Diagnostic Tests.

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To assess kidney function found in acute kidney injury and chronic kidney disease, related to drug reaction and disease such as diabetes.

Patient Preparation
There are no food, fluid, or medication restrictions unless by medical direction. Instruct the patient to refrain from excessive exercise for 8 hr before the test.

Normal Findings
Method: Spectrophotometry.

AgeConventional UnitsSI Units (Conventional Units × 88.4)
Newborn0.31–1.21 mg/dL27–107 micromol/L
Infant0.31–0.71 mg/dL27–63 micromol/L
1–5 yr0.31–0.51 mg/dL27–45 micromol/L
6–10 yr0.51–0.81 mg/dL45–72 micromol/L
Adult male0.61–1.21 mg/dL54–107 micromol/L
Adult female0.51–1.11 mg/dL45–98 micromol/L
Cystatin C
AgeConventional UnitsSI Units (Conventional Units × 74.9)
1–50 yr0.56–0.9 mg/L41.9–67.4 mmol/L
Greater than 50 yr0.58–1.08 mg/L43.4–80.9 mmol/L

Values in older adults remain relatively stable after a period of decline related to loss of muscle mass during the transition from adult to older adult.

The National Kidney Foundation recommends the use of two decimal places in reporting serum creatinine for use in calculating estimated glomerular filtration rate.

Critical Findings and Potential Interventions


Potential critical finding is greater than 7.4 mg/dL (SI: 654.2 micromol/L) (patient not on dialysis).


Potential critical finding is greater than 3.8 mg/dL (SI: 336 micromol/L) (patient not on dialysis).

Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.

Consideration may be given to verification of critical findings before action is taken. Policies vary among facilities and may include requesting immediate recollection and retesting by the laboratory or retesting using a rapid point-of-care testing instrument at the bedside, if available.

Chronic renal insufficiency is identified by creatinine levels between 1.5 and 3 mg/dL (SI: 132.6 and 265.2 micromol/L); CKD is present at levels greater than 3 mg/dL (SI: 265.2 micromol/L).

Possible interventions may include renal or peritoneal dialysis and organ transplant, but early discovery of the cause of elevated creatinine levels might avoid such drastic interventions.

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