Osmotic demyelination from rapid sodium correction

What it is

Sodium correction can harm in both directions, and which harm depends on which way the sodium was moved.

Rapid correction of hyponatremia, that is low Na moved up to high Na, causes osmotic demyelination syndrome (ODS), also known as central pontine myelinolysis. The mnemonic is that the pons will die.

Rapid correction of hypernatremia, that is high Na moved down to low Na, causes cerebral edema. The mnemonic there is that the brain will blow.

How it is treated

The whole of the treatment is in the rate, so the rate is the thing to hold.

Correction of hyponatremia should be no more than 0.5 mEq/L per hr.

In chronic hyponatremia the limits are:

• Max 8-10 mEq/L in 24 hrs
• Less than 18 mEq/L in 48 hrs