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General product information only, not medical advice. Anticoagulation targets and test schedules are set by the treating clinician.
What is CoaguChek? (short answer)
CoaguChek is Roche Diagnostics’ family of point-of-care meters that measure prothrombin time, reported as INR, from a drop of whole blood on a single-use test strip. Roche’s professional manual for the CoaguChek XS system (version 11.0, USA) describes it as intended for use by professional healthcare providers for quantitative prothrombin time testing for the monitoring of warfarin therapy. The meter reads the clotting time and shows the result in about a minute.
Definition and scope
INR is the unit in which blood-clotting time is reported. According to the manual, a result that is too low means a higher risk of blood clots and one that is too high means a higher risk of internal bleeding, and the patient’s doctor determines the target range and how often testing is done.
This page describes the CoaguChek XS system as documented in Roche’s professional user manual (version 11.0 USA, read 2026-11-07). It covers what the system is, how a test proceeds, what its error messages say and what a lab or clinic should have in place. It does not cover other Roche meters, pricing or purchasing.
How a CoaguChek XS test is used in practice
The manual describes the system as a meter plus CoaguChek XS PT test strips. The elements a user handles:
- Code chip. Each box of strips has its own code chip, which carries information such as the strips’ expiration date and lot number. The manual states that using the wrong code chip can produce incorrect results, so the chip in the meter must match the strip container in use.
- Sample. Fresh capillary whole blood or non-anticoagulated venous whole blood; the specification is a sample of at least 8 μL. The manual says not to use glass capillary tubes or capillary tubes containing anticoagulants, and not to use heparinized capillary tubes.
- Timing. Once the blood-drop symbol appears, blood must be applied within 180 seconds, otherwise the meter reports a Time Exceeded error.
- Result. The meter stops the measurement when it determines the blood has clotted, calculates the result and stores it; memory holds 300 results with date and time. The manual also says to confirm the result is displayed in INR.
- Quality control. The strips trigger an internal quality control check; a failed check produces an “Internal Quality Control Failure” message and the strip is unusable.
- Operating conditions. 59°F to 90°F (15°C to 32°C), relative humidity below 85% without condensation, up to 14,000 feet.
Error messages and what the manual says
The professional manual (version 11.0 USA) identifies most errors by their on-screen name rather than by a number; “error 6” and “error 7” appear in notes. Meter software and manual versions differ, so a number you see may not map to a name listed here. If you are asking what a particular error number means, match it to the Error Messages section of the manual for your meter’s version, or call Roche Customer Support at the number the manual gives (1-800-428-4674).
| Message (as named in the manual) | Cause the manual gives | Action the manual gives |
|---|---|---|
| Test Strip | A strip was already inserted when the meter was powered on, the meter timed out, or the strip is not a CoaguChek XS PT strip | Remove the strip and repeat with a new CoaguChek XS PT strip |
| Meter Ambient Temperature | Meter is too cold or too warm to measure correctly | Power off and let it stand about 30 minutes at room temperature |
| Battery | Battery level too low | Insert new batteries; reset date and time if they were lost |
| Test Strip Guide Cover | Guide cover not closed | Close the cover |
| Code Chip | Chip missing, not properly inserted or damaged | Check the correct chip is seated; call Roche support if damaged |
| Test Strip Expired | Code chip and strip lot are beyond the expiry date, or the date setting is wrong | Check the date setting, check the chip matches the strip container, use a strip from a new lot with its own chip |
| Time Exceeded | Blood not applied within 180 seconds of the drop symbol | Repeat with a new strip and a new sample |
| Blood Application | Error applying blood, or sample too small | Repeat with a new strip and sufficient blood; call Roche support if it persists |
| Test Strip Interference | Strip touched or removed during the test | Repeat with a new strip; do not touch the strip during a test |
| Internal Quality Control Failure | Strip failed the internal check | Repeat with a new strip |
Two notes in the manual matter for interpretation. Error 6 may be triggered by hematocrit above 55%, or by blood with a high concentration of oxidizing substances, and on older meters (serial number UP0910000 and lower) in rare cases by very high clotting times above 10 INR. Error 7 can occur in rare cases of unusually long clotting times above 10 INR, and the manual says a repeat of that error requires an alternate method of testing.
Out-of-range results and confirmation
CoaguChek XS PT strips report results from 0.8 to 8.0 INR. If the meter shows below 0.8 or above 8.0, the manual says to repeat the test, and if the same result appears the result must be checked using another method. A “c” shown with the result can mean a very low hematocrit or a sample not collected properly; the manual says to repeat the measurement.
Regulatory classification
openFDA’s 510(k) database lists two Roche Diagnostics CoaguChek entries under product code GJS (“Test, Time, Prothrombin”), reviewed by the Hematology advisory committee: K062925, CoaguChek XS System (decision 2007-01-29, substantially equivalent), and K092940, CoaguChek XS PLUS PST System (decision 2010-03-05, substantially equivalent). openFDA’s classification record for GJS shows device class 2 under 21 CFR 864.7750 (checked 2026-11-07). See our guide to FDA 510(k) premarket notification for what substantial equivalence means.
Where it matters for labs and clinics: a checklist from the manual
Each item below is a requirement or warning stated in the manual; none is a substitute for your facility’s own point-of-care testing policy (see point-of-care testing and CLIA-waived point-of-care testing).
- The code chip in the meter matches the strip container in use, and the chip and strips are not expired (see also test strip expiration).
- Strip containers are closed immediately after removing a strip; humidity and light can deteriorate strips, and the blue reagent line on the strip back may turn pink or purple after such exposure.
- The meter is within its operating temperature range, and the date and time are set correctly.
- The sample type is fresh capillary or non-anticoagulated venous whole blood, at least 8 μL, applied within the timing windows.
- The display unit is INR, not %Q or seconds.
- Results below 0.8 or above 8.0 INR, or repeated errors with those causes, have a defined confirmation method. For quality control programs see CLIA quality control requirements.
Common misunderstandings
- “The meter sets the target range.” It does not. The manual states the patient’s doctor determines the range and testing frequency.
- “Any strip works in any meter.” The manual requires CoaguChek XS PT strips and the matching code chip.
- “A repeated out-of-range display is just a bad strip.” The manual requires the result to be checked by another method.
Frequently asked questions
How do I use the CoaguChek INRange?
The sources read for this page document the CoaguChek XS system only, so they do not describe INRange handling. For any meter, use the manual and training material for that specific model, and ask Roche or the prescribing clinic if unsure.
Is there a home INR test kit?
The manual used here is the professional-use edition for healthcare providers. Whether a patient self-tests at home is decided with their clinician, who also sets the INR target range and schedule.
Where can I buy CoaguChek XS PT test strips?
This page does not sell products or give purchasing advice. What the manual does state is that each box of strips has its own code chip, that the strips must be CoaguChek XS PT strips, and that product questions go to Roche Customer Support (1-800-428-4674, Monday through Friday, 7 AM to 11 PM EST, per the manual).
What does CoaguChek XS error 4 mean?
The version 11.0 professional manual does not list a numbered “error 4”; it names most errors by label, as in the table above. Numbering differs between manual versions, so check the Error Messages section of the manual that came with your meter, or call Roche support.
Sources
- Roche Diagnostics, CoaguChek XS System User Manual, version 11.0 USA (professional edition), read 2026-11-07.
- U.S. FDA via openFDA, 510(k) records K062925 and K092940 and the product classification record for code GJS (21 CFR 864.7750), api.fda.gov, queried 2026-11-07.
