Formula-Based Estimates of the GFR: Equations Variable and Uncertain

Abstract

Regarding the prevalence of chronic kidney disease in the population, estimation of glomerular filtration rate is of importance. Creatinine-based formulas are thus useful as the first step of a prevention strategy. Several creatinine-based formulas have been published. Among these, the Cockcroft-Gault formula and the Modification of Diet in Renal Disease (MDRD) study equation are the most used by physicians. The latter may be automatically reported by laboratories and has thus great success. However, these formulas have limitations. First, the MDRD formulas are not applicable to all populations, notably the healthy one and the patients with abnormal weight (anorectic or obese). Second, we evoke the limitations in the precision of the formulas linked to analytical aspects. Indeed, these analytical limitations remain significant even if they are improved by creatinine standardization. Lastly, we briefly mention the potential impact of these limitations on the epidemiology and the staging of chronic kidney disease.

Are the Creatinine-Based Equations Accurate to Estimate Glomerular Filtration Rate in African American Populations?

“…The difference in reference methods or in creatinine calibration between trials can thus not explain potential differences in estimating GFR (28 -30). In the same view, we know that performance of the MDRD study equation will strongly vary with the GFR range (28,31,32). The MDRD study equation is actually the most accurate in the low-GFR range (stage 3 and 4 CKD), but it underestimates GFR in higher GFR ranges (i.e., in healthy subjects) (28,31,33).…”

“…In the same view, we know that performance of the MDRD study equation will strongly vary with the GFR range (28,31,32). The MDRD study equation is actually the most accurate in the low-GFR range (stage 3 and 4 CKD), but it underestimates GFR in higher GFR ranges (i.e., in healthy subjects) (28,31,33). The mean GFR range in the AASK study, although statistically different, is comparable to the mean GFR in the MDRD study in terms of CKD staging (most subjects with stage 3 or 4 CKD) ( Table 1).…”

“…Accuracy (defined as the percentage of subjects with an estimated GFR within 30% of measured GFR) in this African American subgroup is the best among other subpopulations (88%). Actually, the MDRD study equation logically underestimates GFR in healthy Caucasian subjects because MDRD was built from a Caucasian CKD population and the relationship between GFR and creatinine is not the same in CKD and healthy subjects (28,31). However, this underestimation is not seen in healthy African American subjects.…”

Exploration de la fonction glomérulaire rénale : estimation du débit de filtration glomérulaire

“…L'é tude é pidé miologique amé ricaine National Health and Nutrition Examination Survey (NHANES) rapporte une pré valence de la maladie ré nale dans la population gé né rale adulte de 10,82 % si on retient, comme dé finition de la maladie ré nale, un DFG estimé par MDRD infé rieur à 60 ml/min/1,73 m 2 [22]. Cependant, nous avons vu que la formule MDRD avait une tendance à sous-estimer le DFG chez le sujet sain et cette pré valence de 10,82 % est donc sans aucun doute surestimé e [23]. Dans la même population, la pré valence de la maladie ré nale passe à 9,88 % si la formule CKD-EPI, sensé e être plus pré cise justement chez les patients à DFG normal, est utilisé e à la place de la formule MDRD [4].…”

Contrast enhanced multi-detector CT and MR findings of a well-differentiated pancreatic vipoma

“…As a result, further characterization with dynamic contrast-enhanced MR was deemed necessary. Despite the estimated glomerular filtration rate [13] was 23 mL/min, gadolinium-enhanced MR was considered a safe procedure using Gadoterate Meglumine, a Gadolinium-based contrast agent containing the macro-cyclic ligand Tetraazacyclo-dodecane-tetraacetic Acid [14] . Indeed, no case of Nephrogenic Systemic Fibrosis has been reported to date following its use [14] .…”