Urology Coding Alert

The test isnt new, but the code is: 84152 (prostate specific antigen; complexed). This is for a direct measurement of the complexed portion of the prostate specific antigen (PSA).

PSA travels in the blood, and in normal patients about 90 percent of it is bound (or complexed) to protein. The 10 percent that is not bound to protein is free. In prostate cancer, the amount of bound, or complexed, PSA increases, as does the ratio.

It is impossible to measure complexed PSA by itself unless you have access to a laboratory that has the equipment to do so. There wasnt a code to measure complexed PSA until CPT Codes 2001. But the equipment presents a problem for many labs: The Bayer immunology analyzer costs hundreds of thousands of dollars. Its completely automatic, with perfect timing that cant be compared to hand pipetting, chemists say. And Bayer has the patent on the new complex PSA test. The test cant be run on anything but the Bayer analyzer.

How much of a problem is this? Some pathologists say the complex PSA test is better than what most urologists are ordering now. They are ordering both 84153 (prostate specific antigen [PSA]; total) and 84154 (prostate specific antigen [PSA]; free) and getting the ratio of free to total PSA. The new test just gives one number; the two older tests together rely on two separate analyses done by hand. Each test brings its own analytical variation, so two tests have more variation than one.

Usually, when a urologist gets the PSA report from a laboratory, he or she gets three numbers: the total PSA, the free PSA and the percent of total PSA that is free. The new test just gives one number: the number that urologists are looking for the bound PSA.

The big issue with prostate cancer screening, as with any screening, is specificity vs. sensitivity. The urologist wants the test to be as sensitive as possible because it is supposed to screen for possible prostate cancer. This means that specificity is sacrificed. Testing for only free PSA has a very high false-positive rate: About two out of every three patients who test positive are negative upon biopsy. These patients have to go through an extensive, painful biopsy, and it is unnecessary two thirds of the time, says Lawrence Ferreri, PhD, clinical chemist at Northwest Hospital in Seattle, where the lab performs the complex PSA test (as well as free and total PSA). Screening for the ratio of free to total PSA, or complexed PSA, decreases the number of false positives by a bit.

Running the blood specimen through the analyzer to get a direct measurement of complexed PSA is [...]