Common electrolyte problems.

Electrolyte disorders are among the most frequent and challenging problems facing the admitting physician and many have serious prognostic significance1. Early and informed intervention is necessary, but the outcome may be disappointing. Hyponatraemia with serum sodium below 130 mmol/l occurs in 3–5% of hospital admissions2 and death rates vary from 11–70%3. In patients with hypernatraemia with serum sodium above 150 mmol/l death rates have reached 42%, with significant debility among survivors4.