The percentage of free PSA is calculated using the two results. ARUP uses the Beckman Access Immuoassay System Hybritech Free PSA assay. The free PSA percentage is useful in the differentiation of prostate cancer from benign conditions. Patients with prostate cancer generally have a lower percentage of free PSA than patients with benign prostatic hypertrophy. The percentage of free PSA may be used to aid in the decision of whether a patient should undergo prostatic biopsy.
Prostatic biopsy is required for the diagnosis of cancer.
Catalona WJ, et al. Evaluation of percentage of free serum prostate-specific antigen to improve specificity of prostate cancer screening. Chen DW, et al. Oesterling JE, et al. Ruckle HC, et al.