Pathology/Lab Coding Alert

Question: A 15-year-old diabetic patient came to the emergency room complaining of weakness, tremors and confusion. The physician ordered a stat glucose, which revealed hypoglycemia with a value of 40. The physician gave the patient glucose gel and ordered a glucose retest 15 minutes later. The patient was still hypoglycemic with a value of 55. After providing more glucose tablets, the physician ordered another glucose test 15 minutes later. The patient's glucose was then normal, and he reported relief of his symptoms, so the physician sent him home. When we billed the 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?

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 typically performed over a three-hour period. CPT did not intend modifier -91 to allow you to unbundle those tests and bill each glucose separately. Rather, CPT created this modifier for situations such as you describe, and it 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.

Reader Questions and You Be the Coder were prepared with the assistance of R.M. Stainton Jr., MD, president of Doctors' Anatomic Pathology Services in Jonesboro, Ark.; and Laurie Castillo, MA, CPC, CPC-H, CCS-P, past member of the National Advisory Board of the American Academy of Professional Coders and vice president of ambulatory services for Health Revenue Assurance Associates in Chapel Hill, N.C.