{"id":"osmolality-calculated","name":"Osmolality, Calculated","shortName":"Calculated Osmolality","aliases":["Calculated Osmolality","Osmolality (Calc)","Calc Osmolality","Serum Osmolality, Calculated","Osmolality, Calc","Osmolality Calc","Estimated Osmolality","Estimated Plasma Osmolality","Calculated Serum Osmolality","Osmolality, Estimated","Calculated Osmolarity","Osmolarity, Calculated"],"abbreviations":["Osm Calc"],"loinc":[{"code":"18182-6","primary":true}],"specimen":"calculated","units":[{"ucum":"mosm/kg","display":"mOsm/kg"},{"ucum":"mmol/kg","display":"mmol/kg"}],"referenceRanges":[{"population":"18+","low":275,"high":295,"unit":"mosm/kg","unitDisplay":"mOsm/kg","note":"No lab test page was found that lists a reference interval for the calculated value. This is the interval for measured serum osmolality (Mayo Clinic Laboratories 275–295 mOsm/kg, and Labcorp 275–295 for ages 0 to 60), used because the calculation estimates the same quantity. The Merck Manual describes 275–290 mOsm/kg as normal, and ARUP prints 280–303 mOsm/kg for measured osmolality in ages 17 and older. Calculated results also depend on the formula your lab uses. Houston Methodist's critical-value list calls measured osmolality of 250 mOsm/kg or lower and 320 mOsm/kg or higher, and no critical limit was found for the calculated value itself. 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, 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":"Diagnostic Laboratories: Critical Values","url":"https://www.houstonmethodist.org/critical-values/","publisher":"Houston Methodist"}]}],"review":{"status":"ai-verified","label":"AI-verified against cited sources. Awaiting expert review","lastReviewed":"2026-10-03"},"summary":"Calculated osmolality is an estimate of how concentrated your blood is, worked out from your sodium, glucose and BUN results rather than measured directly.","url":"https://bloodtesttracker.com/markers/osmolality-calculated","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}