Because chronic kidney disease (CKD)
is poorly inferred from serum creatinine alone, NKDEP strongly
encourages clinical laboratories to routinely estimate and report GFR
when serum creatinine is measured for patients 18 and older, when
appropriate and feasible. Routinely reporting eGFR with all serum
creatinine determinations allows laboratories to help identify reduced
kidney function for providers, thus facilitate the detection of CKD.
Routine reporting is easier for some laboratories than it is for
others. The following information will help laboratories appropriately
problems. Below are considerations for
addressing common issues laboratories face when reporting eGFR:
- Since a patient's race is often not
available to laboratories, and because mixed ethnicity can make it
difficult to classify a patient's race, a general recommendation is to
report the eGFR values for both African Americans and non-African
Americans. (See Sample
eGFR Reports.) This practice allows the provider to estimate
the appropriate value for the patient's ethnicity. When ethnicity is
known, it is acceptable to report a single eGFR appropriate for the
- Comments can supplement the
calculated eGFR in cases where the laboratory’s information
system cannot be programmed to report estimates based on race (African
American or not African American). For example, if eGFR is reported
based on the non-African American equation, a comment could state
“For African Americans, multiply by 1.212.”
- The laboratory should exercise
discretion regarding reporting multiple eGFR values when data for age
or gender are not available.
may want to restrict eGFR reporting for some
patients. In cases where information systems cannot identify
patients for whom reporting eGFR is inappropriate, it is suggested that
laboratories report eGFR for all patients and allow the provider to
determine the suitability of a result for a patient’s
≥60mL/min/1.73m2. NKDEP recommends reporting eGFR
values greater than or equal to 60 mL/min/1.73 m2
simply as ≥60 mL/min/1.73 m2, and not
as an exact number. For values below 60 mL/min/1.73 m2,
the report should give the numerical estimate rounded to a whole number
(e.g., "32 mL/min/1.73 m2).
There are three reasons for this recommendation:
- Interlaboratory differences in
calibration of creatinine assays and the imprecision of the
measurements have their greatest impact in the near-normal range and,
therefore, lead to greater inaccuracies for values ≥ 60
mL/min/1.73 m2 .1,
- The MDRD Study equation has been most
extensively evaluated in people with CKD and reduced GFR, and is less
accurate for persons with normal or mildly impaired kidney
- Quantification of eGFR values below
60 mL/min/1.73 m2 has more clinical
implications for classification of kidney function than values above
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