Question

How do you calculate blood volume?

Answer 1

The two most common methods are to use (a) Nadler's Formula or (b) known average values.

Explanation:

Nadler's Formula

Nadler's formula for calculating the blood volume of males is

`color(blue)(|bar(ul(color(white)(a/a) "BV" = 0.3669h^3 + 0.03219w +0.6041color(white)(a/a)|)))" "`

where

`"BV"` = blood volume in litres
`h` = height in metres
`w` = weight in kilograms

For females, the formula is

`color(blue)(|bar(ul(color(white)(a/a) "BV" = 0.3561h^3 + 0.03308w + 0.1833color(white)(a/a)|)))" "`

For a male with a height of 176 cm and a mass of 67 kg,

`"BV" = 0.3669×1.76^3 + 0.03219×67 + 0.6041 = "(2.000 + 2.156 + 0.6041) L" = "4.76 L"`

For a female with a height of 163 cm and a mass of 57 kg,

`"BV" = 0.3561×1.63^3 + 0.03308×57 + 0.1833 ="(1.542 + 1.885 + 0.1833) L" = "3.61 L"`

Average values

Average values give a rough estimate of the blood volume.

The average blood volume for males is 75 mL per kilogram of body mass.

For females, the average blood volume is 65 mL per kilogram.

Thus, for a 67 kg male,

`"BV" = 67 color(red)(cancel(color(black)("kg"))) × "75 mL"/(1 color(red)(cancel(color(black)("kg")))) = "5000 mL" = "5.0 L"`

For a 57 kg female,

`"BV" = 57 color(red)(cancel(color(black)("kg"))) × "65 mL"/(1 color(red)(cancel(color(black)("kg")))) = "3700 mL" = "3.7 L"`

Fat tissue contains fewer blood vessels than ordinary tissue.

For obese individuals, you can use Gilcher's Rule of Five:

The average blood volume is decreased by 5 mL per kilogram.