In this example, blood was collected from a 45-year-old, male, Caucasian subject, and creatinine and cystatin C levels were measured.
There are two ways to calibrate creatinine measurement: traditional vs. IDMS (isotope dilution mass spectrometry) traceable. IDMS traceability indicates that the creatinine method used (such as enzymatic or Jaffe method) has calibration traceable to an IDMS reference measurement procedure, and therefore a validated, IDMS-traceable equation should be used and noted for the eGFR calculation. In the example below, the serum creatinine test was performed via the enzymatic-based creatinine assay using a calibration traceable to IDMS. Because of this, the version of the 4-variable MDRD equation that is IDMS-traceable (as opposed to the version of the equation that uses "traditional" calibration type, which changes the coefficient from 175 to 186, LB Rows 3 and 6) was used to calculate the subject’s eGFR.
Shows the result of serum creatinine measurement from the subject.
|Row 2:||Shows the result of serum cystatin C measurement from the same subject on the same visit.|
Shows an example of an estimated glomerular filtration rate (eGFR) calculated using the serum creatinine result in Row 1 and the 4-variable MDRD equation, which is also IDMS-traceable. The name of the eGFR equation is represented by the LBANMETH variable; in this instance, the eGFR equation used is the US version of the IDMS-4-varaible MDRD formula. Depending on the ethnic background of the population under study, the coefficients and components in the eGFR equation may vary, this is the reason why the text "US VERSION" is included as part of the equation name.
|Row 4:||Shows the result of serum creatinine measurement from the same subject at Week 2 visit.|
|Row 5:||Shows the result of serum cystatin C measurement from the same subject at Week 2 visit.|
Shows eGFR at the Week 2 visit, calculated using the serum creatinine result in Row 4 and the 4-variable MDRD equation, which is also IDMS traceable.
|1||ArBit 01||LB||AB01-001||1||A12567||CREAT||Creatinine||CHEMISTRY||1.5||mg/dL||0.7||1.3||1.5||1.5||mg/dL||0.7||1.3||HIGH||SERUM||ENZYMATIC COLORIMETRY||Week 1||1|
|2||ArBit 01||LB||AB01-001||2||A12567||CYSTATC||Cystatin C||CHEMISTRY||1.4||mg/L||0.52||0.9||1.4||1.4||mg/L||0.52||0.9||HIGH||SERUM||PARTICLE-ENHANCED TURBIDIMETRIC IMMUNOASSAY||Week 1||1||1999-06-19|
|3||ArBit 01||LB||AB01-001||3||A12567||GFRE||Glomerular Filtration Rate, Estimated||CHEMISTRY||51||mL/min/1.73m2||90||120||51||51||mL/min/1.73m2||90||120||LOW||CALCULATION||IDMS-4-VARIABLE MDRD EQUATION-US VERSION||Week 1||1||1999-06-19|
|A12567||CREAT||Creatinine||CHEMISTRY||1.6||mg/dL||0.7||1.3||1.6||1.6||mg/dL||0.7||1.3||HIGH||SERUM||ENZYMATIC COLORIMETRY||Week 2||2||1999-06-26|
|5||ArBit 01||LB||AB01-001||5||A12567||CYSTATC||Cystatin C||CHEMISTRY||1.37||mg/L||0.52||0.9||1.37||1.37||mg/L||0.52||0.9||HIGH||SERUM||PARTICLE-ENHANCED TURBIDIMETRIC IMMUNOASSAY||Week 2||2||1999-06-26|
|6||ArBit 01||LB||AB01-001||6||A12567||GFRE||Glomerular Filtration Rate, Estimated||CHEMISTRY||47|
|90||120||47||47||mL/min/1.73m2||90||120||LOW||CALCULATION||IDMS-4-VARIABLE MDRD EQUATION-US VERSION||Week 2||2||1999-06-26|
The following example shows results from tests on blood, which was collected from a 69-year-old, male, African American subject. The creatinine level was measured, and the estimated glomerular filtration rate was calculated using the CKD-EPI equation, which incorporates creatinine value only.
|Row 1:||Shows the result of serum creatinine measurement from an African American male subject.|
Shows eGFR calculated using the serum creatinine result in Row 1 and the CKD-EPI (Creatinine) equation. The name of the eGFR equation is represented by the LBANMETH variable; in this instance, the eGFR equation used is the US version of the CKD-EPI (Creatinine) formula. Depending on the ethnic background of the population under study, the coefficients and components in the eGFR equation may vary, this is the reason why the phrase "US VERSION" is included as part of the equation name
|1||ArBit 01||LB||AB01-022||1||A12522||CREAT||Creatinine||CHEMISTRY||1.8||mg/dL||0.7||1.3||1.8||1.8||mg/dL||0.7||1.3||HIGH||SERUM||ENZYMATIC COLORIMETRY||Week 1||1|
|2||ArBit 01||LB||AB01-022||2||A12522||GFRE||Glomerular Filtration Rate, Estimated||CHEMISTRY||44||mL/min/1.73m2||90||120||44||44||mL/min/1.73m2||90||120||LOW||CALCULATION||CKD-EPI (CREATININE) EQUATION-US VERSION||Week 1||1||1999-04-02|
The estimated glomerular filtration rate (eGFR) can be calculated using various published, standard equations. eGFR equations are also available for some populations that were not well represented in the cohorts used to develop the original equations, for instance, for people of Japanese ancestry. It is important to note that CDISC does not mandate any one eGFR equation to use. However, please consider eGFR equations that are appropriate for the ethnic background of the population under study.