If an Oral Salt Loading Test is requested, collect the specimen in an acidified 24-hour urine bottle instead of a plain bottle. See instructions in Urine Aldosterone testing.

These tests are of value principally -

In differentiation of the cause of low plasma sodium

To differentiate btween pre-renal and renal failure in certain circumstances where oligouria is present (urine Na)

In acute disturbances of sodium and potassium homeostasis, as a guide to immediate therapy

To assess volume status

While a 24 hour urine collection is the gold standard, in some cases a spot urine may be an adequate alternative.