Reference ranges
PT / INR reference range
Reference ranges describe the interval a laboratory prints next to your result. They are not a diagnosis of what is “normal” for you personally — your clinician interprets results in context.
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What PT / INR measures
Prothrombin time measures clotting speed in a blood sample; INR standardizes that result for comparison, especially when monitoring certain blood thinners.
Why ranges differ
Laboratories set their own reference intervals using their methods, equipment, and population data. That is why the range on your Quest report may differ from a LabCorp report — always use the interval printed on your source document.
Common units
PT / INR is often reported in sec / ratio. Confirm units on your original report before comparing values across time.