Adult Medical Emergency Handbook - Scottish Intensive Care Society

Flow Chart for the assessment and management of a
patient with hyponatraemia*
Hyponatraemia
Hypovolaemic Euvolaemic Hypervolaemic
Clinical signs of Clinical state may
volume depletion not help diagnostically
Plasma urea tends Plasma urea tends to be Usually easier to
to be high rather low rather than high diagnose clinically e.g.
than low Urine sodium >30 mmol/l Heart failure
Urine sodium < 30 mmol/l but may be 30 dietary access to salt Nephrotic
if IV saline has already restricted syndrome
been administered
Fluid restriction (≤ 1litre/d) Treat underlying
+/-Demeclocycline condition
Correct volume depletion (600 - 1200 mg/d) Fluid deprivation
IV 0.9% saline IV 3% (hypertonic) saline and/or
if severe symptoms and demeclocycline
of acute onset (< 48 hrs) may help
Discuss with senior clinician
• *Most difficulty arises in differentiating mild hypovolaemia from
euvolaemic, dilutional, hyponatraemia. In both hypovolaemic
and euvolaemic hyponatraemia plasma osmolality will be low
and the urine will be less than maximally dilute (inappropriately
concentrated). Posm/Uosm will rarely help clinical management.
• Monitor the sodium concentrations carefully (every hour if
necessary during iv therapy).
• In a sick individual consider Addison’s disease and give parenteral
hydrocortisone (100mg) after taking blood for plasma cortisol as
glucocorticoids are anticipated to have little toxicity in this acute
setting and may be life-saving.
218 adult medical emergencies handbook | NHS LOTHIAN: UNIVERSITY HOSPITALS DIVISION | 2009/11