Background:
In consultation with the Department of Medicine and Division of Nephrology, Hypertension, and Kidney Transplantation, the Department of Pathology and Laboratory Medicine will remove race labelling from laboratory reports that include estimated glomerular filtration rate (eGFR). Both the American Society of Nephrology (ASN) and the National Kidney Foundation (NKF) have asserted that race modifiers should not be included in equations used to estimate kidney function given that race is a social, and not a biological, construct.
Calculated results for eGFR that were previously reported as “Non-African American” or “African American” will appear as “eGFR – low estimate” and “eGFR – high estimate”. Actual GFR for an individual patient will likely fall somewhere between the low and high estimates, provided serum creatinine is stable, and with exceptions. Calculated eGFR is not an accurate reflection of GFR in patients on dialysis. Actual GFR may also be outside of the estimated ranges in patients that have very low or very high muscle mass, or those taking medications that affect renal tubular secretion of creatinine. If the eGFR will directly affect clinical decision making (e.g. medication dose or appropriateness), consider using cystatin C to estimate GFR and/or consult with nephrology.
For adults, eGFR will continue to be calculated with the MDRD equation (2006), until an unbiased, accurate, and non-race-based equation is available for creatinine-based eGFR.
Effective date: June 8, 2021
Specimen requirement and testing information:
Specimen: Collect 4.0 mL blood in a light green (lithium heparin), or gold, or red top tube. EDTA plasma is also acceptable. Spin down and separate plasma or serum from cells as soon as possible, and within 2 hours of sample collection.
Test codes: CREGFR, BMPAN, CMPAN, CYSCT
Test methodology: Creatinine is measured by modified Jaffe rate, alkaline picrate assay. Calibration traceable to National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 967. (Isotope dilution mass spec (IDMS) standardization).
Cystatin C is measured by particle-enhanced turbidimetric immunoassay. Calibrators are standardized against the international calibrator standard ERM-DA471/IFCC.
Stability†
Plasma, or serum, after separation from cells:
Ambient: 8 hours
Refrigerated: 48 hours
Frozen: 1 month
† Some tests may have extended stability beyond stated minimum limits. See directory for details.
Turnaround time (TAT):
Creatinine:
STAT: 60 minutes
Routine: 2-4 hours
Set Up Days: Daily
Cystatin C:
STAT: Not available
Routine: 8 hours
Set Up Days: Daily
Specimen required: 2.0 mL plasma. Collect 4.0 mL blood in a light green (lithium heparin) tube. Gold or red top tubes also acceptable.
Minimum volume: 1.0 mL plasma or serum
Rejection criteria:
Specimens that exceed stated stability, unlabeled/mislabeled/mismatched specimens, or specimens submitted in leaking containers.
References ›
A summary of all tests offered by our laboratory services can be found here: http://www.pathology.uci.edu/services/index.asp
Sincerely,
Bridgit O. Crews, PhD, DABCC
Director
Clinical Chemistry, Toxicology and Point-of-Care Testing
Kam Kalantar-Zadeh, MD, MPH, PhD
Chief
Nephrology, Hypertension and Kidney Transplantation
Edwin S. Monuki, MD, PhD
Chair
Department of Pathology and Laboratory Medicine
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