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| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
SERUM OSMOLALITY
Test CodeOSMS
Preferred Specimen
GOLD TOP TUBE
Specimen Stability
3 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Severe hemolysis
Clinical Significance
In vitro diagnostic test for the direct quantitative measurement of serum osmolality. Osmometry is a technique for measuring the concentration of solute particles in a solution. Osmotic pressure governs the movement of water (or solvent) across membranes, such as the glomerular membranes in the kidney and the membrane of a capillary vessel. The permeability of these membranes also allows the passage of small molecules and ions, but not large molecules like protein. The serum test is used mainly to evaluate hyponatremia. Certain toxins and therapies that affect an individual's fluid balance can also be evaluated with serum osmolality testing. High levels may be due to diabetes mellitus, hyperglycemia, uremia, hypernatremia, conditions causing decreased ADH secretion, and dehydration, while lower levels may be due to ADH oversecretion, adrenal disorders, water intoxication, hyponatremia, or hypothyroidism.
