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Test Code LAB107 Osmolality, Serum

Useful For

Osmolality is a measure of the number of dissolved solute particles in solution.  It is determined by the number and not by the nature of the particles of solution.  Dissolved solutes change the physical properties of solutions, increasing the osmotic pressure and boiling point and decreasing the vapor pressure and freezing point.  The osmolality of serum increases with dehydration and decreases with overhydration. 

The patient receiving intravenous fluids should have a normal osmolality; if the osmolality rises, the fluids contain relatively more electrolytes than water.  If it falls, relatively more water than electrolytes is present.  Both serum and urine osmolality must be measured to assess osmolar clearance.

Performing Laboratory

Asante Rogue Regional Medical Center (ARRMC)

 

Performing Department

Chemistry

Specimen Required

Specimen Minimum Volume

Minimum volume is 0.5 ml

Specimen Stability Information

Centrifuge and refrigerate within 2 hours of collection

Stable 48 hours if aliquoted and refrigerated at 2° to 8° C

Send to Laboratory refrigerated

Reject Due To

  • Quantity not sufficient (QNS)
  • Lack of Two Patient Identifiers:
    • 1-Patient’s First & Last name 
    • 2-Patient’s Date of Birth

Day(s) Performed

Monday through Sunday 

Method Name

Freezing Point Depression 

CPT Code Information

83930  -  Osmolality; blood

Billing Code

2050938