TABLE 1.

Estimation and measurement of GFR techniques and formulae in ESLD

Estimation of GFR	Variables	Pros	Cons
CG equation5,6	Age, weight, SCr, TBW, sex	Still used for drug dosing, because of availability of pharmacokinetic data from drug dosing studies	Does not take into account body surface area Creatinine laboratory values were not standardized Did not include ESLD patients in derivation
MDRD-4 and MDRD-67	Age, sex, ethnicity, serum creatinine, urea, and albumin	MDRD-6 has relatively better correlation with mGFR especially among those with mGFR of <30 mL/min/m2 Accounts for BSA Albumin was included	Derived from cohort of healthy individuals, ESLD not included Lack of pharmacokinetic data for drug dosing Race was included as a variable Overestimates eGFR
CKD-EPI: SCr8	Age, sex, creatinine, race	Standardized creatinine Better accuracy at eGFR >60 mL/min/1.73 m2	Race as a variable led to over estimation of eGFR in AA. Less accuracy of <60 mL/min/m2 ESLD population not included Overestimation SCr secretion increases with reduction of GFR Impacted by muscle mass and diet Hyperbilirubinemia may interfere with SCr measurement
CKD-EPI: CysC	Cystatin C	Independent of muscle mass, gender, and diet	Underestimates eGFR >60 mL/min Affected by nonkidney nonliver medical conditions Costly and not widely available ESLD population not included Lack of standardized testing
CKD-EPI SCr-CysC		Better accuracy for eGFR of <60 mL/min compared with CKD-EPI	ESLD population not included
GRAIL9	Creatinine, blood urea nitrogen, age, gender, race, and albumin Temporal testing CKD stage	Prognostic ability to predict CKD post-LT Superior accuracy in estimating eGFR of <30 mL/min, that is, group requiring decision for LT alone vs SLKT Specifically modeled for those with ESLD	Inclusion of race as a variable More studies needed to validate
CKD-EPI NMR10	Age, sex, and creatinine	Removes as a variable can account for sarcopenia	Needs more studies
Measurement of GFR
Inulin	Urinary clearance of inulin	Gold standard, completely filtered, no reabsorption or secretion	Costly Time consuming, limiting serial assessments Invasive
Iohexol, 51Cr-EDTA, 99mTc-DTPA, 99mTc- 125I-IOT, 125I	Exogenous markers	Less expensive and more available than inulin Less technically challenging	Costly and time consuming limiting Serial measurements Anaphylactic risk with iohexol Radiation exposure Overestimation of GFR in hypervolemia/ascites in ESLD
Carboxymethylated dextran3,10	Exogenous dextran	Point of care, rapid testing Ease of testing and serial measurements Validated in other hypervolemic state, that is, CHF	Needs validation studies in ESLD

AA, African Americans; BFA, body surface area; CG, Cockcroft Gault; CHF, congestive heart failure; CKD-EPI, chronic kidney disease epidemiology collaboration; CKD NMR, chronic kidney disease nuclear magnetic resonance; ⁵¹Cr-EDTA, ⁵¹Chromium-ethylenediamine tetraacetic acid; Cys, cystatin C; ESLD, end-stage liver disease; GFR, glomerular filtration rate; ¹²⁵I-IOT, ¹²⁵I-iothalamate; MDRD, modification of diet in renal disease; ⁹⁹mTc-DTPA, ⁹⁹mTc-diethylene triamine penta-acetic acid; SCr, serum creatinine; TBW, total body water.