Internal Medicine Coding Alert

Question: When we billed three blood glucose tests (82947, Glucose; quantitative, blood [except reagent strip]), the payer denied two of the tests. How should we bill to get paid for all three tests?

Michigan Subscriber

Answer: When providers repeat the same laboratory test for the same patient on the same day, append modifier -91 (Repeat clinical diagnostic laboratory test) to the test code. This lets the payer know that the tests you are billing are not duplicates.

The instructional notes in CPT caution that you should not use this modifier to bill for tests that you must repeat because of testing problems with specimens or equipment. Also, you should not use it for codes that, by definition, require serial measurements.

For instance, the code for a glucose tolerance test (82951, Glucose; tolerance test [GTT], three specimens [includes glucose]) includes glucose dose and a number of glucose measurements the physician typically performs over a three-hour period.

CPT did not intend modifier -91 to allow you to unbundle those tests and bill each glucose test separately.

Rather, CPT created this modifier for situations such as you describe, so the modifier should solve your problem.

To recover reimbursement for the other two tests you mention, resubmit the claim with documentation supporting the use of modifier -91.