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Lab Dept:
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Chemistry
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Test Name:
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OSMOLALITY
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General Information
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Lab Order Codes:
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OSM
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Synonyms:
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Osmo
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CPT Codes:
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83930 – Osmolality; blood
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Test Includes:
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Osmolality concentration reported in mOsm/kg.
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Logistics
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Test Indications:
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Determination of osmolality can be useful in the assessment of electrolyte and acid/base disorders. Comparisons can determine the status of renal water regulation settings of severe electrolyte disturbances, as might occur in diabetes insipidus.
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Lab Testing Sections:
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Chemistry
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Phone Numbers:
Minneapolis:
Saint Paul:
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612-813-6280
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651-220-6550
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Test Availability:
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Daily, 24 hours
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Turnaround Time:
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4 hours
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Special Instructions:
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N/A
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Specimen
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Specimen Type:
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Blood
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Container:
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Green top (Li Heparin) tube preferred
Alternate tube: Red top (plain, no gel) tube
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Draw Volume:
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0.6 mL blood
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Processed Volume:
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0.2 mL plasma/serum
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Special Processing:
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Lab Staff: Centrifuge specimen, remove serum/plasma aliquot into plastic sample cup. Run within 4 hours or store at refrigerated temperatures.
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Patient Preparation:
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None
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Sample Rejection:
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Mislabeled or unlabeled specimen
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Interpretive
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Reference Range:
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275 - 295 mOsm/kg
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Critical Values:
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N/A
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Limitations:
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N/A
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Methodology:
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Freezing point depression
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References:
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Advanced Instruments Osmometer Model 2020 User’s Guide, 2025 Rev16, 081508, Two Technology Way, Norwood, MA 02062
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Tietz Textbook of Clinical Chemistry and Molecular Diagnostics (2006) Elsevier Saunders Company, pp 991 - 994
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Jacobs & DeMott Laboratory Test Handbook Lexi-Comp, Inc (2001) Hudson, OH, 5th Edition, pp 236-237
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