Hypernatraemia

1. Is the patient unwell?

• ABCDE approach 

2. Is the result a true value?

• Could the sampling method have affected the result?
• Is there a previous level?

3. Does the patient have any symptoms or signs?

• May indicate the significance and rapidity of electrolyte change
• Muscle weakness, extreme thirst, confusion, lethargy, irritability, seizure, coma

4. Are there culprit drugs? - consider stopping them

• Lithium if causing diabetes insipidus (do not stop without contacting psychiatry)

5. Causes? - treat them

• Severe dehydration, possibly related to diabetes insipidus. Frequently seen near end of life in severe frailty/dementia

Severe (Na⁺ >160 mmol/L)

• If patient is volume depleted give 0.9% saline IV, rate adjusted to fluid reviews
• If patient is euvolaemic give 5% dextrose IV, rate adjusted to fluid reviews
• Check Na⁺ level 4 hourly – rate of reduction of serum Na⁺ must not occur more rapidly than 10 mmol/L per day

Mild/Moderate (Na⁺ ≤160 mmol/L)

• Treat cause – rehydrate as appropriate

Treat consequences and associated causes

• Check renal function and calcium.
• Monitor urine output – if > 300ml/h for >2 consecutive hours, or fluid balance >1 l negative over 24h consider diabetes insipidus
• Check blood sugar – if >30 consider Hyperosmolar Hyperglycaemic State- treat as per this protocol

Seek senior advice if concerns and in particular if:

• If serum osmolality is high (greater than 330), more frequent monitoring may be required, with a maximum hourly correction of 2-5 mOsm/kg. ALSO check glucose in this situation
• Rate of change in serum Na⁺ occurs more rapidly than 10 mmol/L per day
• No response to initial treatment
• If you are uncertain regarding whether this is indication/not of patient approaching end of life

Cardiac monitoring or HDU review?

• No indication for cardiac monitoring. HDU review only if clinical concern