Appendix A - Part 2: Anthropometrics | Pharmacotherapy Principles and Practice Study Guide, 6e | Pharmacotherapy Principles & Practice

ANTHROPOMETRICS

Creatinine Clearance Formulas

Formulas for Estimating Creatinine Clearance in Patients with Stable Renal Function

Cockcroft-Gault Formula

Adults (age 18 years and older)¹:

CrCl (men) = \frac{(140 - age) \times weight}{SCr \times 72}

CrCl (women) = 0.85 \times above value

where CrCl is creatinine clearance (in mL/min), SCr is serum creatinine (in mg/dL [or μmol/L divided by 88.4]), age is in years, and weight is in kilograms.

Traub-Johnson Formula

Children (age 1–18 years)²:

CrCl = \frac{0.48 \times height \times BSA}{SCr \times 1.73}

where BSA is body surface area (in m²), CrCl is creatinine clearance (in mL/min), SCr is serum creatinine (in mg/dL [or μmol/L divided by 88.4]), and height is in centimeters.

Formula for Estimating Creatinine Clearance From a Measured Urine Collection

CrCl (mL / min) = \frac{U \times V}{P \times T}

where U is the concentration of creatinine in a urine specimen in mg/dL, V is the volume of urine in mL, P is the concentration of creatinine in serum at the midpoint of the urine collection period in mg/dL, and T is the time of the urine collection period in minutes (eg, 6 hours = 360 minutes; 24 hours = 1440 minutes). Procedures for obtaining urine specimens should stress the importance of complete urine collection during the collection time period.

IDMS-Traceable MDRD Equation (Used for Creatinine Methods with Calibration Traceable to IDMS)

For creatinine in mg/dL:

X = 175 \times {creatinine}^{- 1.154} \times {age}^{- 0.203} \times constant

For creatinine in μmol/L:

X = 175 \times {(creatinine / 88.4)}^{- 1.154} \times {age}^{- 0.203} \times constant

where X is the glomerular filtration rate, constant for white men is 1 and for women is 0.742, and constant for African Americans is 1.212.

Ideal Body Weight

IBW is the weight expected for a non-obese person of a given height. The IBW formulas below and various life insurance tables can be used to estimate IBW. Dosing methods described in the

literature may use IBW as a method in dosing obese patients.

Adults (age 18 years and older)³:

\begin{matrix} IBW (men) & = & 50 + (2.3 \times height in inches over 5 ft) \\ IBW (women) & = & 45.5 + (2.3 \times height in inches over 5 ft) \end{matrix}

where IBW is in kilograms.

Children (age 1–18 years)² under 5-feet tall:

IBW = \frac{{height}^{2} \times 1.65}{1000}

where IBW is in kilograms and height is in centimeters.

Children (age 1–18 years) 5 feet or taller:

\begin{matrix} IBW (males) & = & 39 + (2.27 \times height in inches over 5 ft) \\ IBW (females) & = & 42.2 + (2.27 \times height in inches over 5 ft) \end{matrix}

where IBW is in kilograms.

Appendix A - Part 2: Anthropometrics

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