{"id":"osmolality","name":"Osmolality, Serum","shortName":"Osmolality","aliases":["Serum Osmolality","Osmolality","Osmolality, Plasma","Osmolality (Measured)","Osmolality, S","Osmolality, Serum or Plasma","Plasma Osmolality","Osmolality, Measured","Serum Osm","Osmolalidad sérica","Serumosmolalität"],"abbreviations":[],"loinc":[{"code":"2692-2","primary":true}],"specimen":"serum-or-plasma","units":[{"ucum":"mosm/kg","display":"mOsm/kg"},{"ucum":"mmol/kg","display":"mmol/kg"}],"referenceRanges":[{"population":"18–60","low":275,"high":295,"unit":"mosm/kg","unitDisplay":"mOsm/kg","note":"Mayo Clinic Laboratories prints 275–295 mOsm/kg for all ages, and Labcorp prints the same for ages 0 to 60. ARUP prints 280–303 mOsm/kg for ages 17 and older, and the Merck Manual describes 275–290 mOsm/kg as normal, so the upper limit differs by lab. Background on causes and testing comes from the Merck Manual (water and sodium balance; hyponatremia) and MedlinePlus. Use the range printed on your own report first.","sources":[{"title":"Osmolality, Serum (test ID UOSMS)","url":"https://schnecklab.testcatalog.org/show/UOSMS","publisher":"Mayo Clinic Laboratories (catalog copy hosted by Schneck Medical Center)"},{"title":"Osmolality (test 002071)","url":"https://www.labcorp.com/tests/002071/osmolality","publisher":"Labcorp"},{"title":"Osmolality (test 002071), sample patient report","url":"https://files.labcorp.com/testmenu-d8/sample_reports/002071.pdf","publisher":"Labcorp"},{"title":"Osmolality, Serum or Plasma (test 0020046)","url":"https://ltd.aruplab.com/Tests/Pub/0020046","publisher":"ARUP Laboratories"},{"title":"Water and Sodium Balance","url":"https://www.merckmanuals.com/professional/nephrology/fluid-metabolism/water-and-sodium-balance","publisher":"Merck Manual Professional Version"},{"title":"Hyponatremia","url":"https://www.merckmanuals.com/professional/nephrology/electrolyte-disorders/hyponatremia","publisher":"Merck Manual Professional Version"},{"title":"Osmolality Tests","url":"https://medlineplus.gov/lab-tests/osmolality-tests/","publisher":"MedlinePlus (US National Library of Medicine)"}]},{"population":"61+","low":280,"high":301,"unit":"mosm/kg","unitDisplay":"mOsm/kg","note":"Labcorp interval for ages 61 and older. Mayo Clinic Laboratories prints 275–295 mOsm/kg for all ages, and ARUP prints 280–303 for ages 17 and older.","sources":[{"title":"Osmolality (test 002071)","url":"https://www.labcorp.com/tests/002071/osmolality","publisher":"Labcorp"}]}],"review":{"status":"ai-verified","label":"AI-verified against cited sources. Awaiting expert review","lastReviewed":"2026-10-03"},"summary":"Serum osmolality shows how concentrated your blood is: how many dissolved particles, mostly sodium, glucose and urea, it holds per kilogram of fluid.","url":"https://bloodtesttracker.com/markers/osmolality","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}