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Test Code CREA Creatinine

Important Note

Do not use specimens obtained through catheters used to infuse hyperalimentation fluid.

Additional Codes

Cerner

NextGen

Creatinine Serum

Creatinine Serum

Cr

 

Alternate Name(s)

Creatine Blood

Creatine Serum

Creatine Plasma

Estimated Glomerular Filtration Rate

 eGFR

Useful For

Serum creatinine and urinary creatinine excretion is a function of lean body mass in normal persons and shows little or no response to dietary changes. The serum creatinine concentration is higher in men than in women. Since urinary creatinine is excreted mainly by glomerular filtration, with only small amounts due to tubular secretion, serum creatinine and a 24-hour urine creatinine excretion can be used to estimate the glomerular filtration rate.

Serum creatinine is increased in acute or chronic renal failure, urinary tract obstruction, reduced renal blood flow, shock, dehydration, and rhabdomyolysis. Causes of low serum creatinine concentration include debilitation and decreased muscle mass. Exercise may cause an increased creatinine clearance.

Methodology

Enzymatic, Two-point rate

Patient Preparation

None

Collection Instructions

  • Do not use specimens obtained through catheters used to infuse hyperalimentation fluid.
  • Standard phlebotomy practices.

Specimen Requirements

Container

Specimen Type

Tube

Lithium Heparin Plasma

PST

 or  or 

Serum

 or 

SST

 or  or 

 

Stability

Storage

Temperature

Stability

Room Temperature

18-28°C

≤ 5 days

If separated within 4 hours

Refrigerated

 2-8°C

≤ 30 days

If separated within 4 hours

Frozen

≤-18 °C

Indefinite

If separated within 4 hours

Rejection Criteria

Gross Hemolysis

Result Reporting and Reference Values

  • Creatine reported in mg/dL

AGE

Gender

Low

High

Critical Low

Critical High

<1 week

N/A

0.2

1.1

N/A

10.0

7 d – 2 months

N/A

0.15

0.6

N/A

10.0

2 months – 2 years

N/A

0.15

0.4

N/A

10.0

2 – 9 years

N/A

0.15

0.6

N/A

10.0

10 – 13 years

N/A

0.2

0.9

N/A

10.0

13 – 18 years

N/A

0.2

1.1

N/A

10.0

18 - 150 years

Male

0.66

1.25

N/A

10.0

18 - 150 years

Female

0.52

1.04

N/A

10.0
  • Adult eGRF: >60 mL/min/1.73m2

Reflex Testing

An Estimated Glomerular Filtration Rate (eGFR) is reported with Creatine results on patients ≥18 years of age using the 2021 CKD-EPI creatinine equation.

Limitations

  • Ortho reports the following additional biases:
    • Dipyrone (Metamizol) at 18.0 mg/dL shows a negative bias
    • Tolazamide at 4.5 mg/dL shows a negative bias
    • Proline- Patient receiving hyperalimentation fluids contain proline may show a positive bias
    • Lidocaine- patients on long term lidocaine therapy may show a positive bias
  • The following interpretive data is visible to the practitioner:
    • Patient receiving hyperalimentation fluids containing Proline may have a positive bias. Specimens contaminated with Dobutamine from IV fluids show a significant negative bias. Patients on long term Lidocaine therapy show a significant positive bias. Dipyrone and N-acetylcysteine show significant negative bias.