Originally Posted by
CliffordK
I'm not sure why urine salt tests aren't performed more frequently. I suppose due to the high variability in the levels. But, that would be one of the tests for hyponatremia.
Your kidneys can selectively eliminate or retain sodium and potassium ions largely independent of the serum levels of these ions. Urine osmolality is probably a better indicator of a serum electrolyte imbalance.