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Anthropometric formulas
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Adults
Lean body weight (LBW) Devine equation: LBW (Males) = 50 + [ 2.3 x (60 - Height in inches) ] LBW (Females) = 45.5 + [ 2.3 x (60 - Height in inches) ]
Hume equation: LBW (Males) = (0.3281 x Weight in kg) + (0.33939 x Height in cm) - 29.5336 LBW (Females) = (0.29569 x Weight in kg) + (0.41813 x Height in cm) - 43.2933
The Devine method is the default result. For short stature patients (less than 60 inches), the Hume method is utilized when its result is less than baseline LBW (50kg for males, 45.5kg for females) and greater than Devine.
Please note that neither of these method is valid in amputees.
Body surface area (BSA) Mosteller equation: BSA = Square root of (HT X WT) / 3600 where: HT = height in centimeters WT = weight in kilograms
Creatinine Clearance (CrCl) per Jelliffe Multistep Method 1. Estimate urinary creatinine excretion rate
E (males) = LBW x (29.305 -[0.203 x (age)]) E (females) = LBW x (25.3 -[0.18 x (age)])
2. Correct for rising serum creatinine
E = E - [4 x LBW x (SrCr1-SrCr2)] / D where LBW = lean body weight in kilograms SrCr1= the latest serum creatinine SrCr2= the earlier serum creatinine D = the number of days between
3. Calculate corrected creatinine clearance (CrCl)
CrCl/1.73 m2 = (E * 0.12) / (SrCr * BSA) where SrCr is the most recent serum creatinine in mg/dL BSA = Body surface area
Creatinine Clearance (CrCl) per Cockroft and Gault 1. Calculate body weight adjusted for obesity* (ABW) ABW = LBW + [0.3 x (WT-LBW)] where WT = actual body weight LBW = lean body weight
*Obesity defined as BMI > 30..
2. Calculate creatinine clearance (CrCl)
CrCl Males = [Wt x (140 - Age)] / (SCr x 72) CrCl Females = 85% of male value where SCr is the most recent serum creatinine in mg/dL Wt = LBW in normal weight patients or ABW in obese patients
Optional CrCl methods Cockcroft and Gault TBW This variation of the C&G equation uses Total Body Weight instead of Ideal Body Weight. Be aware however, that this tends to over-estimate CrCl in larger patients. CrCl Males = [TBW x (140 - Age)] / (SCr x 72) CrCl Females = 85% of male value
Cockcroft and Gault Normalized Removes weight from the C&G equation. Some find this variation useful in patients whose body size is substantially different from average. This is also the method used when "Adjust CL to IBW" is checked. CrCl Males = (140 - Age) / SrCr CrCl Females = 85% of male value
Jelliffe 1973 Weight is not used in this equation either, therefore, some find this method useful in patients whose body size is substantially different from average: CrCl Males = 98 - (0.8 x (Age-20)) / SrCr CrCl Females = 90% of male value
MDRD (abbreviated) Derived from a large study of patients with a wide range of kidney function. Some feel this is a more accurate GFR method overall. GFR Males = exp[ 5.228 - ( 1.154 x log{SrCr} ) - ( 0.203 x log{Age} ) GFR Female = 74.2% of male value For African Americans multiply by 1.21
It is important to note that MDRD calculates GFR which does not directly correlate to CrCl
Salazar and Corcoran Derived from a study of obese patients. Some recommend this method for obese patients instead of the standard equations. CrCl Males = { ( 137 - Age ) x [ ( 0.285 x Wt) + (12.1 x Ht2 )] } / (51 x SrCr) CrCl Females = { ( 146 - Age ) x [ ( 0.287 x Wt) + (9.74 x Ht2 )] } / (60 x SrCr)
Pediatrics
Lean body weight (LBW) Traub equation: LBW = (HT2 x 1.65)/1000 where HT = height in centimeters
Body surface area (BSA) Haycock equation: BSA = 0.024265 x HT 0.3964 x WT 0.5378 where HT = height in centimeters WT = weight in kilograms
Creatinine Clearance (CrCl) per Schwartz
CrCl = (k x Ht/Scr) x (1.73/BSA) where HT = height in centimeters SrCr = the most recent serum creatinine in mg/dL k = 0.33 if weight < 2.5 kg k = 0.45 if age <1 year k = 0.55 if age 1-12 years
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