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# frozen_string_literal: true
require_dependency "renalware/clinics"
# Total Body Water (TBW) calcuated using WATSON
# References:
# - https://qxmd.com/calculate/calculator_344/total-body-water-watson-formula
#
# Total Body Water
# TBW = 2.447 - 0.09156 X age + 0.1074 X height + 0.3362 X weight
# (females) TBW = -2.097 + 0.1069 X height + 0.2466 X weight
#
# Water in Litres
# Age in years
# Height in cm
# Weight in kg
module Renalware
module Clinics
class TotalBodyWater
pattr_initialize [:height!, :weight!, :age, :sex]
NOTHING = nil
SEX_PROC_MAP = {
M: ->(age:, height:, weight:) { 2.447 - 0.09156 * age + 0.1074 * height + 0.3362 * weight },
F: ->(height:, weight:, **) { -2.097 + 0.1069 * height + 0.2466 * weight }
}.freeze
NOOP = ->(**) { NullObject.instance }
def self.calculate(dp: 2, **args)
new(**args).calculate(dp: dp)
end
def calculate(dp: 2)
return NOTHING if height_cm.zero?
return NOTHING if weight_kg.zero?
return NOTHING if age.to_i.zero?
proc_for_sex = SEX_PROC_MAP.fetch(sex_sym, NOOP)
proc_for_sex.call(
age: age,
height: height_cm,
weight: weight_kg
).round(dp)
end
private
# Note sex can be nil but here that would evaluate to :""
def sex_sym
sex.to_s&.to_sym
end
def height_cm
height.to_f * 100
end
def weight_kg
weight.to_f
end
end
end
end
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18 entries across 18 versions & 1 rubygems