weight_height: Calculates different weight variables

In amp.dm: Data Management Tools for Pharmacometrics

Calculates different weight variables

Description

This function calculates different variables based on weight and height and conversion from or to kilograms

Usage

weight_height(wt = NULL, ht = NULL, sex = NULL, bmi = NULL, type = "bmi")

Arguments

wt	vector with weight values, in either kg or lb depending on the type (see details)
ht	vector with height values in cm (see details)
sex	vector with SEX values (Where female is defined as a value of 1)
bmi	vector with BMI values (see details)
type	character with the type to be used for the calculations (see details)

Details

Currently the following types are defined within the function:

Convert units

• "kg-lb" : Convert units from kg to lb using the formula

  \textrm{Weight (kg)} = \textrm{Weight (lb)} \cdot 2.20462262

• "lb-kg" : Convert units from lb to kg using the formula

  \textrm{Weight (lb)} = \frac{\textrm{Weight (kg)}}{2.20462262}

Body mass index

• "bmi" : Calculates body mass index (BMI) using the standard formula (Quetelet1842,

  \textrm{BMI} = \frac{\textrm{Weight (kg)}}{\textrm{Height (m)}^{2}}

Body Surface Area

• "bsa": Body Surface Area, according to Gehan and Georg,

  \textrm{BSA} = \exp{-3.751} \cdot \textrm{Height (cm)}^{0.422} \cdot \textrm{Weight (kg)}^{0.515}

• "bsa2": Body Surface Area, according to DuBois and DuBois,

  \textrm{BSA} = 0.007184 \cdot \textrm{Height (cm)}^{0.725} \cdot \textrm{Weight (kg)}^{0.425}

• "bsam": Body Surface Area, according to Mosteller,

  \textrm{BSA} = \sqrt{\frac{\textrm{Weight (kg)} \cdot \textrm{Height (cm)}}{3600}}

• "bsah": Body Surface Area, according to Haycock,

  \textrm{BSA} = 0.024265 \cdot \textrm{Height (cm)}^{0.3964} \cdot \textrm{Weight (kg)}^{0.5378}

• "bsal": Body Surface Area in normal-weight and obese adults up to 250 kg, according to Livingston,

  \textrm{BSA} = 0.1173 \cdot \textrm{Weight (kg)}^{0.6466}

Fat free mass

• "ffmj": Fat free mass, according to Janmahasatian:

  \textrm{FFM}=\frac{9270 \cdot \textrm{Weight (kg)}}{k +\left(l \cdot \textrm{BMI}\right)}

  , where k is 6680 for males and 8780 for females and l is 216 for males and 244 for females.

• "ffms": Fat free mass in Indian patients, according to Sinha:

  \textrm{FFM}=\frac{9270 \cdot \textrm{Weight (kg)}}{k \cdot l \cdot \textrm{BMI}^{0.28}}

  , where k is 6680 for males and 8780 for females and l is 0.77 for males and 0.70 for females.

Lean body mass

• "lbmb" : Calculates lean body mass (LBM), according to Boers:

  \textrm{LBM} = k \cdot \textrm{Weight (kg)} + l \cdot \textrm{Height (cm)} - m

  , where k is 0.407 for males and 0.252 for females, and l is 0.267 for males and 0.473 for females, and m is 19.2 for males and 48.3 for females.

• "lbmj" : Calculates lean body mass (LBM), according to James:

  \textrm{LBM} = k \cdot \textrm{Weight (kg)} - l \cdot \left(\frac{\textrm{Weight (kg)}}{\textrm{Height (cm)}}\right)^2

  , where k is 1.10 for males and 1.07 for females, and l is 128 in males and 148 in females.

• "lbmp" : Calculates lean body mass (LBM) for children up to 14 years, according to Peters:

  \textrm{LBM} = 3.8 \cdot 0.0215 \cdot \textrm{Weight (kg)}^{0.6469} \cdot \textrm{Height (cm)}^{0.7236}

Predicted Normal Weight

• "pnw" : Calculates the Predicted Normal Weight for obese patient, according to Duffull:

  \textrm{PNWT} = k \cdot \textrm{Weight (kg)} - l \cdot \textrm{Height (cm)} \cdot \textrm{BMI} - m

  , where k is 1.57 for males and 1.75 for females, and l is 0.0183 for males and 0.0242 for females, and m is 10.5 for males and 12.6 for females.

Value

a vector with calculated values

Author(s)

Richard Hooijmaijers

Examples

tmp <- data.frame(id=1,WT=runif(3,70,120),HT=runif(3,160,220))
weight_height(wt=tmp$WT,ht=tmp$HT,type="bmi")
# example for use in dplyr
tmp |> dplyr::mutate(BMI = weight_height(wt=WT,ht=HT,type="bmi"))

amp.dm documentation built on March 13, 2026, 5:08 p.m.