Hyponatraemia is the most common electrolyte abnormality that we see.
It’s important to be able to quickly diagnose the causes of this.
Below is a 6 minute video that summarises an approach to the causes of hyponatraemia.
Although not as simplistic as this, but my simple approach is:
1. Correct for increased glucose
2. If the patient is wet, it’s failure- cardiac, renal, liver
3. If the patient is dry, it’s losses via skin or GIT tract OR it is adrenocortical insufficiency( the urine Na is up and the aldosterone level is low)
4. If the patient is euvolaemic it is either water intoxication or SIADH(urine Na is high)
Now lets look at that in a little more detail.