Table 2.

Duration of symptoms and mean serum electrolyte levels

	<20 days	20-40 days	>40 days
Mean serum sodium level (mmol/l)	137	133	133
Mean serum potassium level (mmol/l)	4.8	3.6	3.2
Mean serum bicarbonate level (mmol/l)	26	30	28
Mean serum chloride level (mmol/l)	90	90	91