Koreksi Natrium

Quick formula for correction of hyponatraemia with 3% saline

EDITOR - The formula to correct hyponatraemia in Bhalla et al’s
otherwise excellent article on hyponatraemic seizures in young children is
misleading and potentially dangerous(1). As they rightly state, acute
correction of hyponatraemia should occur in a child at a rate of no faster
than 2-3 mmol/l per hour. They then not only give an incomplete formula
to calculate the volume of sodium that must be given, but suggest giving
the entire deficit over 30-90 minutes. For a child with a serum sodium
concentration of 116 mmol/l this might mean correction to 125 mmol/l over
90 minutes, or 6 mmol/l per hour.
The correct, and simpler, method to correct hyponatraemia with 3% saline
is as follows:

1. 3% saline (513 mmol/l) contains approximately 1 mmol sodium in 2 ml.

2. Total body water is 60% of body weight.

3. Therefore the volume (in ml) of 3% saline which will raise the serum
sodium by 1 mmol/l is twice total body water (in litres).

4. This volume can then be infused at whatever rate is chosen to correct
the serum sodium.
For example, a child of 10 kg has a total body water of 6 litres.
Therefore 12 ml 3% saline will raise the serum sodium by 1 mmol/l. Hence
an infusion of 24 ml/hour will raise the serum sodium by 2 mmol/l per
hour.

1. Bhalla P, Eaton FE, Coulter JBS, Amegavie FL, Sills JA, Abernethy
LJ. Hyponatraemic seizures and excessive intake of hypotonic fluids in
young children. BMJ 1999;319:1554-7.



http://pathlabs.rlbuht.nhs.uk/hyponatraemia.pdf