The obese patient

Definitions

1. Overweight = BMI 25-29
2. Obesity = BMI 30-39
3. Morbid obesity = BMI 40-49
4. Super obesity = BMI >50

1. Total body weight (TBW)= Actual weight
2. Ideal body weight (IBW)= Calc. based on height & weight
3. Lean body mass (LBM)= Calc. based on subtracting body fat from TBW

Estimating Patient Weight

Multiple formulas to estimate weight, below are most common:

1. Estimated male TBW = 93.2 + 3.29[arm circumference (cm)] + 0.43[height (cm)]
2. Estimated female TBW = 64.6 + 2.15[arm circumference (cm)] + 0.54[height (cm)]
3. Estimated male IBW in kg = height in cm - 100
   1. More accurate IBW estimate:
      1. IBW (male) in kg = 50kg + 2.3kg for each in. over 5ft
4. Estimated female IBW in kg = height in cm - 105
   1. More accurate IBW estimate:
      1. IBW (female) in kg = 45kg + 2.3kg for each in. over 5ft
5. Estimated LBM = 1.3 x IBW
6. Others:
   1. Epocrates has IBW calculator
   2. [Medcalc]

Medication Adjustments in Obesity

Obesity alters hepatic/renal clearance and volume of distribution (Vd) of many drugs