CPT 85610: prothrombin time (PT/INR) clotting test. What Medicare pays and what to ask
The PT/INR test checks how fast blood clots, often to monitor blood thinners. Here is what 85610 covers and the Medicare lab rate.
What this code means
CPT 85610 measures how long blood takes to clot. The INR result is used to monitor blood thinners such as warfarin.
It can be done in a lab or with a small device at the point of care.
Why the bill can be much higher than the Medicare rate
Patients on blood thinners may have the test often, so the number of tests billed matters.
The blood draw is billed on its own line, unless a finger-stick device was used.
| If a line is billed at | It would be |
|---|---|
| 5x the Medicare rate | $21.45 |
| 10x the Medicare rate | $42.90 |
| 20x the Medicare rate | $85.80 |
The Medicare rate is a published benchmark, not a legal ceiling on what a provider may charge. Our free scan flags a line as worth a closer look when it is billed at more than 10 times the Medicare rate.
Questions worth asking before you pay
- How many PT/INR tests were done, and on which dates?
- Was the blood draw billed as well, and was one needed?
- Is the test listed only once for each date?
Check every line against the official Medicare rates in about a minute. The scan is free.
Related codes
Source: Medicare Clinical Laboratory Fee Schedule (CMS, 2026), national payment limit. Last updated October 2026. This page is general information, not legal or medical advice. Rates change each year and a hospital bill can include charges that the benchmark does not cover.