management of hyponatraemia
Last reviewed 01/2018
Specific cause should be treated. Renal function should be assessed (dialysis may be required if poor).
If not dehydrated and good renal function then decision to treat is dependent on the plasma sodium concentration. If the plasma sodium concentration is greater than 125mmol/l then treatment is rarely necessary. However, if plasma sodium is less than 125 mmol/l then the patient should be restricted to 0.5-1 litre of water/day. Should consider whether to give short term treatment with frusemide (e.g. 40-80mg/day IV or PO for two days). Occasionally, SIADH is treated by producing nephrogenic diabetes insipidus, e.g. with demeclocycline.
If the patient is dehydrated and the kidney function is good then normal saline can be administered. If an emergency, e.g. patient fitting or comatosed, then should consider administration of rapid IVI of normal saline or hypertonic 5% saline at 70mmol Na+/h. Should monitor electrolytes and possible heart failure. Consult biochemist or nephrologist concerning management.