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Coagulation Studies
Normal range 11-13.5 seconds. Specimen: Plasma (sodium citrate).
Also known as: pro time.
Combined adult band. LabVals does not publish separate men's, women's, or pediatric ranges for Prothrombin Time (PT); those can be narrower than the band shown.
| Specimen | Plasma (sodium citrate) |
|---|---|
| Conventional range | 11-13.5 seconds |
| SI range | 11-13.5 seconds |
| Conversion factor | ×1 (conventional → SI) |
| Critical value | > 30 seconds (marked bleeding risk) |
| Panel | Coagulation Studies |
Convert any Prothrombin Time (PT) result between units on the unit converter.
The standard teaching reference range for Prothrombin Time (PT) is 11-13.5 seconds. This value is measured in plasma (sodium citrate).
For Prothrombin Time (PT), the commonly taught critical (panic) value is: > 30 seconds (marked bleeding risk). Critical results are reported to the provider immediately under your facility's policy.
Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population - always use the range printed on the actual result.
Above the range
What causes a high Prothrombin Time (PT)? Read as its own page
Below the range
What causes a low Prothrombin Time (PT)? Read as its own page
At the bedside
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