excess serum sodium in mmol/L =
= (measured serum sodium level in mmol/L) - (normal serum sodium level in mmol/L) =
= (measured serum sodium level in mmol/L) – 140
excess serum sodium in mmol =
= (excess serum sodium in mmol/L) * (extracellular fluid volume in liters)
where:
• Methods for estimating total body water are discussed in Chapter 2. For the implementation I will use the method from Race and Rathbun (02.12.04), which gives a rough estimate.
• Extracellular fluid represents about 45% of total body water.
Each 17 mmol sodium indicates 1 gram sodium chloride.
grams of sodium chloride administered =
= (excess serum sodium in mmol) / 17
Each 5 mL level teaspoon delivers about 6 grams of salt.
number of level teaspoons of salt administered =
= (grams of sodium chloride) / 6
Limitations:
• This assumes that the administration was shortly before presentation, so that the measured serum level reflects the peak serum concentration.
