Test Overview
Colorimetic Rate
Evaluation of renal function
1-4 years: 0.2 - 0.6 mg/dL, 5-11 years: 0.4 - 0.9 mg/dL, 12-150 years, male: 0.7 - 1.3 mg/dL, female: 0.5 - 1.0 mg/dL
2021 CKD-EPI ≥ 60 mL/min/1.73m^2
The 2021 CKD-EPI equation should not be used to predict EGFR in unstable patients or in children. A GFR estimate between 15 and 59 for ≥ 3 months is classified as Chronic Kidney Disease (Stage 3 or 4).
GFR estimate can be interpreted accurately only during a steady state of creatinine balance. GFR estimate will overestimate true GFR if serum creatinine is rising (such as acute kidney failure) and will underestimate true GFR if serum creatinine is declining (such as resolution of acute kidney failure).
EGFR is not calculated when serum creatinine values are <0.1mg/dL.
A pediatric glomerular filtration rate (PGFR) can be calculated using the CKiD Under 25 (U25) GFR equation to aid with diagnosis of chronic kidney disease in children. This will be provided on patients age 12months – 17 years and will be based on height and measured creatinine. The equation uses age and sex as specified. The most recent Height (collected within the previous 6 months of testing) and Date of Height will be provided in Michart and the calculation of PGFR will be performed in Soft. If a recent height or no height is available in MiChart, the height used for the calculation will be imputed from CDC growth charts using the 50th percentile for age and sex.
The laboratory must have an order or request for CREAP (Creatinine with serum HT/DOHT)
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.
Calculation not valid for patients less than 18 years of age and for pregnant women.
The 2021 CKD-EPI formula used to calculate the EGFR result has not been validated in patients > 100 years of age.
The EGFR should NOT be used for pharmacy drug dosing.
The calculation is not useful for estimating GFR in unstable patients or patients with acute renal failure. There are other conditions where the EGFR will be less accurate and should not be utilized. These include: extremes of body size and weight, skeletal muscle disease, paraplegia or quadriplegia, vegetarian diet, and for the calculation of dose of potentially toxic drugs that are excreted by the kidney. EGFR is NOT an orderable test.
A pediatric glomerular filtration rate (PGFR) can be calculated using the CKiD Under 25 (U25) GFR equation to aid with diagnosis of chronic kidney disease in children. This will be provided on patients age 12months – 17 years and will be based on height and measured creatinine. The equation uses age and sex as specified. The most recent Height (collected within the previous 6 months of testing) and Date of Height will be provided in Michart and the calculation of PGFR will be performed in Soft. If a recent height or no height is available in MiChart, the height used for the calculation will be imputed from CDC growth charts using the 50th percentile for age and sex.
This is an orderable test, and requires the laboratory to order test code CREAP (creatinine serum with HT/DOHT)
Test Details
2 hours
- GFR (Glomerular Filtration Rate)
- Glomerular Filtration Rate (GFR)
- eGFR
STAT requests for this test will be performed on a STAT basis (supervisory staff approval is not required).
Specimen Requirements
Collect specimen in an SST tube. Centrifuge, aliquot serum into a plastic vial and refrigerate.
Additional Information
The Jaffe reaction used for creatinine on the Atellica CH analyzer can exhibit a positive bias or interference with a number of different compounds. The most common are high levels of ascorbic acid and certain cephalosporin antibiotics (Cefpirone, Cefoxitin, Cefazolin, and Cephalothin). Patients may exhibit fairly dramatic changes in serum creatinine (0.5 - 1.0 mg/dL increases) if samples happen to be drawn at peak drug levels.