OSMOLALITY, BLOOD Mnemonic OSMOS Specimen Collection Requirements Collect Acceptable Samples: Serum or Li Heparin plasma Collect 1 SST, plain red, or PST Tube Heparin tubes should be at least ½ full. Handling Allow serum to clot completely at room temperature (minimum: 30 minutes). Centrifuge and separate serum or plasma from cells ASAP. Preferred Volume 0.5 mL Minimum Volume 0.2 mL Transport Refrigerated (2-8°C) Rejection Criteria Samples that do not meet SHS labeling requirements. Samples collected in containers other than the types listed above. Samples not stored or shipped at proper temperature. Moderately hemolyzed serum or plasma samples. Stability AFTER SEPARATION FROM CELLS: Serum Ambient(15 – 25 °C): 2 days Refrigerated (2 - 8°C): 8 days Frozen (at or below -20°C): 7 days Plasma Ambient(15 – 25 °C): 3 days Refrigerated (2 - 8°C): 3 days Frozen (at or below -20°C): 7 days Testing Information Performed 7 days/week Method Freezing Point Depression Referral Lab Samaritan Health Services Laboratories-GSRMC Reference Values Reference Values Serum/Plasma Osmolality < 72 hours: 266 – 295 mOsm/kg H2O ≥ 72 hours – 60 years: 275 – 295 mOsm/kg H2O > 60 years: 280 – 301 mOsm/kg H2O CPT Codes 83930 Last Updated: Friday, December 18, 2020 02:34:47 PM