Pathology/Lab Coding Alert

Question: When our lab tests for serum creatinine and cystatin C for patients with kidney disease, we-ve started getting denials. What could be the source of the problem?

Maryland Subscriber

Answer: If you have not updated your code for cystatin C, using an old code might be one reason you-re getting a denial. CPT 2008 added a new code for the test: 82610 (Cystatin C).

Old way: Prior to 2008, your lab probably reported the cystatin C blood test with the unspecified code 83520 (Immunoassay, analyte, quantitative; not otherwise specified). You may have trouble showing medical necessity for the test if you-re not using the updated CPT code.

You may have another medical-necessity problem if physicians are ordering both creatinine 82565 (Creatinine; blood) and cystatin C to monitor renal function -- payers may consider performing both tests redundant.

Here's why: Serum concentration of cystatin C is a good marker for renal function and is not affected by other conditions such as inflammation, body mass or diet. Although physicians may also use serum creatinine and blood urea nitrogen (BUN) as indicators of kidney function, they-re not likely to order those tests and cystatin C at the same time solely to assess renal status.

You should check with your payers for coverage rules regarding these tests, and ensure that you-re using the most up-to-date codes to describe your lab tests.