Pathology/Lab Coding Alert

Just be careful not to double bill.

You’ve heard it said that you can never bill for lab tests that involve calculated values, and that’s true — sort of.

Let’s get to the nitty gritty with some specific examples to make sure you know when you can and can’t bill for calculated values.

Bill the Underlying Test

Sometimes a physician requests a lab test value, and you have to perform a different test plus a calculation to give the doc what he orders. Can you bill for that calculation?

For instance: The physician requests an international normalized ratio (INR) value for a patient on anticoagulation Coumadin therapy. The lab performs a prothrombin time (PT) test, which provides the result in seconds and the normalized ratio to account for the non-linear nature of clotting ability.

“In this case, you should bill the core test that the lab performs, which is 85610 (Prothrombin time),” says William Dettwyler, MTAMT, president of Codus Medicus, a laboratory coding consulting firm in Salem, Ore. “You should not bill an additional code for the INR calculation.”

Bottom line: You’re essentially billing for a “calculated value” that your lab reports by billing for the underlying test that the lab must perform to achieve the desired, calculated result.

Example 2: “On occasion, our physicians prefer an absolute neutrophil count (ANC) only. In order to provide this calculation, the lab needs to perform both a white blood cell (WBC) count and an automated differential,” says Bobbi Andera, BSMT, AMT, regulatory/coding manager for Sanford Laboratories in Sioux Falls, S.D.

In this case, you should report the WBC as 85048 (Blood count; leukocyte (WBC), automated), and the automated differential as 85004 (Blood count; automated differential WBC count).

Compliance alert: You need to be careful in situations like these two examples when the physician orders one thing and the lab performs something else. Even though the lab performs the test necessary to calculate the result that the physician requests, you could be in dicey audit territory.

Do this: You should have a policy approved by the lab director, compliance officer, and pathologist that establishes standards for these situations. For instance, “The lab’s policy should be that if a physician orders an ANC, then the lab will perform an automated differential (85004),” Dettwyler says.

Caution: Remember that if the lab performs an automated complete blood count (CBC) with auto diff (85025, Blood count; complete [CBC], automated [Hgb, Hct, RBC, WBC and platelet count] and automated differential WBC count), the lab results typically list the WBC and ANC percentage and absolute count as well as counts for other cell types.

Do not use the 85004/85048 combination instead of or in addition to 85025 if the CBC with auto diff is ordered. A Correct Coding Initiative (CCI) edit bundles 85004 and 85048 into 85025. Also note that a CBC pays $10.61 while 85004 and 85048 together pay $12.29 (2014 Clinical Laboratory Fee Schedule National Limit Amount), which could lead to overbilling.

Bill Just Once, Please

Although the prior examples show that you can bill for a calculation by billing only for the underlying test, it’s still true that Medicare and other payers won’t pay for a calculated value in addition to the underlying test.

Example 3: A physician orders total thyroxine (T4), triiodothyronine (T3) uptake, and a free thyroixine index, which represents a calculated free thyroxine (FT4) value. The lab performs (84436, Thyroxine; total) and (84479, Thyroid hormone [T3 or T4] uptake or thyroid hormone binding ration [THBR]) and calculates the free thyroxine index, which they report as an indirect proportional estimate of FT4.

Avoid: Although there is a CPT® code for FT4 (84439, Thyroxine; free), you should not report 84439 for the calculated FT4 based on the results of 84436 and 84479. In fact, CCI lists 84436 and 84479 as column 2 codes for 84439 with a modifier indicator of “0,” meaning that you cannot report the codes together under any circumstances.

Example 4: The physician orders a lipid panel (80061, Lipid panel), and the results include a calculated value for low-density lipoprotein (LDL) cholesterol. You should bill for 80061, not 80061 plus 83721 (Lipoprotein, direct measurement; direct measurement, LDL cholesterol). Again, a CCI edit restricts billing those codes together under normal circumstances.

Exception: If the triglyceride level is too high (400 mg/dl or more) to permit an accurate LDL cholesterol calculation, the lab may additionally perform the LDL test and report 83721-59 (Distinct procedural service) in addition to 80061.