The total, free and complexed PSAs increased with age (linear trend, p < 0.001), but the percent free and complexed PSA and the free/complexed PSA did not change significantly with age. Total PSA GM increased from 0.74 μg/l, for men 40-49 years, to 1.82 μg/l for men 80 years and older. These molecular differences explain the possibility to distinguish free from total PSA (F/T ratio). Free and complexed PSA have different clearances and significant differences between clearance of free PSA after radical prostatectomy (RP) and after open surgery for benign prostatic hyperplasia (BPH) are observed. This finding has been exploited in the use of the ratio of free to total PSA and complexed PSA (cPSA) as a means of distinguishing between prostate cancer and BPH as a cause of an elevated PSA. (See 'Serum free and bound PSA' below and 'Complexed PSA' below.) Complexed PSA: This test directly measures the amount of PSA that is attached to other proteins (the portion of PSA that is not "free"). This test could be done instead of checking the total and free PSA, and it could give the same amount of information, but it is not widely used. The ease of calibration and the accuracy of free PSA assays in comparison with assays of the PSA-ACT complex suggest that measurements of free to total PSA most accurately reflect the inverse of the proportion of PSA complexed to ACT in serum. An additional portion of PSA that is complexed with α 2-macroglobulin can be measured only if the complex is opened and the PSA epitopes become accessible. Of the total PSA (tPSA) in serum, 10-30% is not bound to serum proteins and is called free PSA (fPSA). Comparison of the clinical value of complexed PSA and total PSA in the discrimination between benign prostatic hyperplasia and prostate cancer Authors Michael Froehner 1 , Oliver W Hakenberg , Rainer Koch , Uta Schmidt , Axel Meye , Manfred P Wirth Affiliation Circulating PSA can be divided into two main forms: complexed and free. Most circulating PSA is bound to a variety of protease inhi- bitors, most commonly a-1-antichymotrypsin, and the proportion of the total PSA concentration which is free or unbound is relatively small. PSA, a protein produced by prostate gland cells, circulates through the body in two ways: either bound to other proteins or on its own. PSA traveling alone is called free PSA. The free-PSA test measures the percentage of unbound PSA; the PSA test measures the total of both free and bound PSA. Over the past years, the assessment of equimolarity has been typically performed by the characterization of the recovery of IS 96/670, consisting of 90% PSA-ACT and 10% PSA free form, by marketed PSA assays. OoAOoQ.

complexed psa vs free psa