1. What is the difference between urine osmolality and specific gravity?
Specific gravity is a common part of a urinalysis. It evaluates the weight of solids in water. Osmolality and specific gravity usually change in parallel to each other. When large and heavy molecules (such as glucose and protein) are present in the urine, however, the results will diverge. Specific gravity will be increased more, due to the weight of the molecules, while urine osmolality will be increased less, reflecting the number of molecules.
2. Will everyone have an osmolality test?
No. It is not a routinely ordered test. The majority of patients will maintain normal sodium levels and a normal water balance most of the time without medical intervention.
