Skip to 0 minutes and 11 secondsThe other formula is MDRD formula or the so called Levey equation. The formula says creatinine clearance is equal to 186 times serum creatinine to the minus 1.154 power times age to the minus point 203 power. And there are correction factors for female is point 742. For African American is 1.21 and for African American female is point 898 And this formula was published in 2002. Based on a study called modification of diet in renal disease study. The results were in patient of 70 years old or younger. So this is different patient population compared with the Cockroft equation. So here the MDRD formula for the estimate of a white male patient age 40 and the serum creatinine one milligram per decilitre.

Skip to 1 minute and 30 secondsSo creatinine clearance based on the MDRD formula is eighty seven point eight milliliter per minute per one point seven three meters square. And this is fairly consistent with the value by CG equation that we obtained earlier. On the other hand, for the white female age 40 and the serum creatinine one miligram per decilitre. The creatinine clearance turns out to be sixty five point one milliliter per minutes per one point seven meters square. And this also compared rather consistently with the sixty two point nine milliliter per minutes per one point seven meters square. By the Cockroft equation, using ideal body weight and adjusted for the body surface area.

Skip to 2 minutes and 31 secondsSo here we get in the conclusion that It's a good practice to adjust creatinine clearance, to the standard body surface area of one point seven three meters square. There are several advantages for the MDRD formula. First, the result have been calibrated for average body surface area of 1.73 meters square. And therefore there's no need to calculate ideal body weight. And there's no need to calculate body surface area. And there's no age limit. However, we do need to adjust for the gender factor male or female. And we also need to adjust race factor. Comparison of estimates. GFR in the mild to moderate ESRD range estimated by Cockcroft equation gives 51.4 milliliter per minute.

Skip to 3 minutes and 36 secondsBy MDRD equation, it gives forty five point two milliliter per minute. And by the isotope method (by chromium 51 isotope method). It gives the value of forty four point six milliliter per minute. And presumably that isotope method should give the most accurate measurement. And therefore here we can see that the MDRD estimate is closer to the true value. Which is represented by the GFR determined by isotope. And we noticed that the Cockroft equation tends to overestimate due to weight and underestimate due to age.

GFR Estimation : MDRD Formula

In this step, Prof. Lee illustrates the correction factor, examples, and the advantages for MDRD formula (Levey Equation).

First, the correction factor depends on the races and the gender.

Secondly, there are several advantages of using this method, including no need to calculate IBW and BSA, and no age limit.

However, we need to adjust it for gender and race factor.

Finally, we are able to compare the estimations between different methods.

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This video is from the free online course:

Pharmacokinetics: Drug Dosing in Renal Disease

Taipei Medical University