Pathology/Lab Coding Alert

Question: Our lab performs a Chlamydia antibody panel that tests for IgG an IgM for three distinct species (C. trachomatis, C. pneumoniae, and C. psittaci). How should we code the service,especially given that CPT does not provide a distinct code for the IgG class?

Washington Subscriber

Answer: You should report the panel using 86631 (Antibody; Chlamydia) and 86632 (Antibody; Chlamydia, IgM). Specifically, you'll report 86631 x 3 and 86632 x 3.

Here's why: Although you're correct that CPT provides a distinct code for the IgM antibody class (86632) but not IgG, there is an instructional note that explains how to overcome the omission. You can report the IgG class using the general antibody code -- 86631 in this case.

The instructional note for codes 86602-86804 states, "When a coding option exists for reporting IgM specific antibodies, the corresponding nonspecific code may be reported forperformance of ... an IgG analysis."

Notice: That means you're using 86631 to report the IgG antibodies -- the same code you would use to perform an antibody analysis not specific for a particular immunoglobulin class.

Use units for different species: Because you're testing for IgG and IgM antibodies to three different Chlamydia species -- C. trachomatis, C. pneumoniae, and C. psittaci -- you should list three units of each code for each immunoglobulin class. That's why you should list 86331 x 3 and 86332 x 3.

Follow payer modifier direction: Instead of units, some payers may ask you to enter each code on a separate line and use a modifier such as 59 (Distinct procedural service) or 91 (Repeat clinical diagnostic laboratory test) to indicate that each code represents a distinct test. Follow your payers' direction for reporting these codes when you perform more than one test.