Measurement of Urinary Electrolytes — Indications and Limitations

THE measurement of urinary sodium, potassium and chloride has become an increasingly common practice in hospitalized patients. Despite their widespread acceptance, however, it is clear that these laboratory tests often yield information that is either of no clinical value or, at best, is easily predictable from knowledge of the dietary intake. The usefulness of these measurements is further limited by the frequent failure to distinguish between the concentration of electrolytes in a random, spot, urine sample and the total excretion in 24 hours; this distinction is often crucial, given the wide range of both dietary electrolyte and water intake and . . .