MDRD

Total drug clearance is the sum of nonrenal clearance and renal clearance (Clren). According to the MDRD-2 formula, the estimated GFR (eGFR) is a function of serum creatinine (SCr in mg/dl) and age (Age in years). It has the unit ml/min per 1.73 mA2. 

The effect of hemofiltration on drug elimination can be estimated from serum creatinine (SCr), age, and the MDRD-2 formula to predict the combined effect of filtration rate (eGFR = GFRresidual + HFR) on drug clearance and drug half-life during hemofiltration. 

MDRD, per the Modification of Diet in Renal Disease study. 

The National Kidney Foundation (NKF) developed a classification system for CKD (Table 23-11.1 The staging system defines the stages of CKD based on GFR level, but also accounts for evidence of kidney damage in the absence of changes in GFR, as in stage 1 CKD. The GFR is calculated using the abbreviated Modification of Diet in Renal Disease (MDRD) study equation ... 

MDRD Formula for Estimating Glomerular Filtration Rate (from the Modification of Diet in Renal Disease Study)3... 

Conventional calibration MDRD equation [used only with those creatinine methods that have not been recalibrated to be traceable to isotope dilution mass spectrometry (IDMS)]... 

I DMS-Traceable MDRD Equation (Used Only with Creatinine Methods that Have Been Recalibrated to Be Traceable to IDMS)... 

The outcome of planning should include the generation of a method definition requirement document (MDRD) in which all stake holders agree, prior to method development, on the critical attributes of the method. Considerations such as what impurities/degradation products should be monitored, requisite reporting thresholds, the need for an MS-compatible method, if identical methods for DP and DS are required, etc., should be clearly decided and agreed upon by all stakeholders. 

It is also useful to assure that internal (company specific) practices are adhered to in method development by making these considerations part of the MDRD. Based on the voice of the customer surveys, several technical and practical method attributes have been identified within our organization. 

Final method development is started with a review of the available methods from early development. The methods are evaluated against the method requirements set in the MDRD. Generally, the method is optimized or re-developed in order to fulfill the requirements, using the approaches detailed previously in this chapter. 

Dietary protein has long been thought to play a role in the progression of chronic renal disease, but clinical trials have not consistently shown that dietary protein restriction is beneticial. A meta-analysis including the Modification of Diet in Renal Disease (MDRD) Study, of 1413 patients from 1966 to 1994 showed that dietary protein restriction slows the progression of both diabetic and non-diabetic renal disease (see Klahr et al., 1994). It is advisable to restrict protein intake moderately to 1 g/kg daily. 

Kopple ID, Greene T, Chumlea WC, Hollinger O, Ma-roni BJ, Merrill D et al. Modification of diet in Renal disease Study Group. Relationship between nutritional status and GFR results from the MDRD study. Kidney Int 2000 57 1688-703. 

When to stop metformin in people with diabetes mellitus and abnormal renal function continues to be debated. It has been suggested that it should not be used in those with an eGFR (MDRD) of less than 60 ml/minute (122). However, this would exclude many people who have been taking metformin for many years without apparent ill effect. Others have recommended using the Cockcroft-Gault equation (SEDA-29, 527), which is preferable. 

Calculate CM s renal function using both the MDRD equation and the... 

There is growing popularity of the formulae used to predict eGFR. While Cockcroft/Gault is the oldest, the MDRD formulae has gained greater use since it is most useful at GFR < 60 ml/min/1.73m [111]. How reliable these values are with rapidly changing serum creatinine values is problematic. 

An alternative to the measurement of the Ccr is the use of either nomograms or formulae to estimate the glomerular filtration rate. The two most widely used equations are the Cockcroft-Cault and the Modifica-hon of Diet in Renal Disease (MDRD) study equations [46,47]. 

Reexpressed MDRD Study equation for standardized serum creatinine [51 [ ... 

Figure 5. Bar graph showing estimated GFR (MDRD calculation) of patients presenting with AIN in two large case series. Although GFR does improve from presentation, patients do not return to their previous baseline kidney function and are left with chronic kidney disease. The dark bars represent data from reference 27, the light bars from reference 25.

MDRD modification of diet in renal disease NRF nuclear respiratory factors... 

Calculated Clearance. The mathematical relationship between plasma creatinine and GFR can be improved by correcting for the confounding variables that make that relationship nordinear. More than 25 different formulas have been derived that estimate GFR using plasma creatinine corrected for some or all of gender, body size, race, and age. These may produce a better estimate of GFR than serum creatinine alone. Indeed the National Kidney Foundation of the United States has recommended that such estimates should be used in preference to serum creatinine, and that either the Cockcroft and Gault or Modification of Diet in Renal Disease (MDRD) formula should be used in adults. The Schwartz and Counahan-Barratt formulas are recommended for use in children. 

They observed that the MDRD equation provided more accurate assessment of GFR than either the Cockcroft and Gault equation or measured creatinine clearance. The MDRD formula has several advantages (1) it was developed and validated in a large population, (2) it was developed with a population that included both European-Americans and African-Americans, (3) it does not require patient weight, (4) it was validated against an iothalamate clearance estimate... 

Plasma creatinine is an imperfect marker of GFR and therefore it is not altogether surprising that formulas based predommantly upon it are imperfect. Their use cannot circumvent the very significant spectral interferences affecting plasma creatinine measurement (i.e., hemolysis, icterus, and lipemia) and the formulas are unsuitable for use in patients with acute renal failure, in whom plasma creatinine concentrations are changing rapidly. Additionally, the formulas are critically susceptible to variations in creatinine assay calibration and specificity. Notwithstanding the MDRD formula is thought to improve the estimation of GFR compared with plasma creatinine alone. 

In practice, there may be little to choose between the Cockcroft and Gault formula and the more recently described MDRD equation,and which is chosen will be... 

Harmoinen A, Lehtimaki T, Korpela M, Turjanmaa V, Saha H. Diagnostic accuracies of plasma creatinine, cystatin C, and glomerular filtration rate calculated by the Cockcroft-Gault and Levey (MDRD) formulas. Clin Chem 2003 49 1223-5. 

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