1. Hyponatraemia John Foote Causes, assessment and management

4. Acute Hyponatraemia and Cerebral Swelling Hyponatreamia Normal

9. Water Homeostasis Plasma Osmolality (mOsmol/Kg) Oral water intake Renal water clearance 270 280 290 300

10. Osmolar Control of ADH Secretion 270 280 290 300 Plasma Osmolality (mOsmol/Kg) Plasma ADH

12. Response to Vascular Volume Deficit Vascular volume deficit Osmolar ADH control Non-osmolar ADH control Vascular volume maintained at the cost of ECF dilution Volume deficit

18. Pseudohyponatraemia Normo-osmolar Hyponatraemia Normal Pseudohyponatraemia 7% 20% 93% 80% [Na + ] plasma water: 150 mmol/l 150 mmol/l [Na + ] whole plasma: 140 mmol/l 120 mmol/l Non-aqueous phase Aqueous phase

26. Is Serum [Na + ] < 125 mmol/l? Neurological symptoms? Duration of hyponatraemia? Yes Chronic hyponatraemia Yes No Emergency correction with 3% saline 1-2 ml/kg/hour until [Na] > 125 mmol/l Urgent correction with 3% saline 1-2 ml/kg/hour until symptoms resolve, continue at 0.5 mmol/l/hour thereafter <24 h >24 h or unknown Routine assessment and management No Adverse outcome unlikely