Treatment of Hypernatrem

iaMy Notes

By Dr Sahar Salem Sasy

Calculate the

water deficit = Body weight (kg)x %of TBW x Serum Na /140 -1

% of TBW :

Equation 1:

TBW = weight (kg) x correction factor

Correction factors

Children: 0.6 Nonelderly men: 0.6 Nonelderly women: 0.5 Elderly men: 0.5 Elderly women: 0.45

Estimate the effect of 1 L of any infusate on serum Na+ concentration as follow:

Equation 2:

Change in serum Na+ = (infusate Na+ - serum Na+) ÷ (TBW + 1)

Equation 3:

If the infusate contain Na and Ka use the following formula :

Change in serum Na+ = ([infusate Na+ + infusate K+} – serum Na+) ÷ (TBW + 1)

Equation 2 allows for the estimation of 1 L of any infusate on serum Na+ concentration. Equation 3 allows for the estimation of 1 L of any infusate containing Na+ and K+ on serum Na+.

Common infusates and their Na+ contents include the following:

5% dextrose in water (D5 W): 0 mmol/L

0.2% sodium chloride in 5% dextrose in water (D5 2NS): 34

mmol/L

0.45% sodium chloride in water (0.45NS): 77 mmol/L

Ringer's lactate solution: 130 mmol/L

0.9% sodium chloride in water (0.9NS): 154 mmol/L

The result will show how much Na will be reduced by 1L infusate (-x)

The rate will be calculated as follow :

10 ÷ (x) = (A1)L of solution is required The goal is to reduce the

patient’s serum sodium by no more than 10 mmol/L in a 24-hour period

(-x ) X 1000 (ml)=(A)ml to convert from L to ml.

Add the insensible water loss to calculate the total amount of fluid required (ml or cc) per 24h.

A1+(1000 ml to 1500 ml insensible loss )=A2(ml)

A2 ÷ 24= A2 ml or cc /24h

All The Best