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Prostate-specific antigen (PSA) assays measure the single-chain glycoprotein found in the cytoplasm of the epithelial cells lining the acini and ducts of the prostate gland. [1]
PSA is specific to prostate tissue; however, PSA assays should be used in conjunction with other diagnostic tools to aid in the diagnosis of prostate cancer in men. Elevated PSA levels not only can be found in cancer patients, but also in those with Benign Prostatic Hyperplasia (BPH), prostatitis and infarction. PSA levels have shown to be of value in detecting recurrence of tumors as well as the success of prostatectomy.[2-5]
Bostwick Laboratories® offers total PSA, complexed PSA, and a calculated free/total PSA ratio. The complexed PSA assay measures the major immunoreactive form of PSA which is primarily of alpha-1-antichymotrypsin (ACT). [6,7] Studies have shown that when using the free/total PSA ratio, differentiation of prostate cancer and BPH can be determined, therefore reducing the number of biopsies. Ratios above 20% have been shown to be associated with BPH, where the lower ratios have been seen in patients with prostate cancer. [2]
References:
- Wang MC, Valenzuala LA, Murphy GP, and Chu TM. Purification of a human prostate-specific antigen. Invest. Urol. 1979;17:159.
- Methods. 20 ed. 2001. pgs 1040-41.
- Catalona WJ, Smith DS, Ratliff TL. et al. Measurement of Prostate-specific antigen in serum as a screening test for Prostate Cancer. New Eng. J. Med. 1991;324(17):1156.
- Cooner WH, Mosley BR, Rutherford LL. et al. Prostate cancer detection in a clinical urological practice by ultrasonography, digital rectal examination and prostate specific antigen. J. Urol. 1990;143:1146.
- Oesterling JE. Prostate specific antigen: a critical assessment of the most useful tumor marker for adenocarcinoma of the prostate. J. Urol. 1991;145:907.
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- Lilja H. Significance of different molecular forms of serum PSA. Urol C Clin North Am 1993;20:681-686.
- McCormack RT, Rittenhouse HG, Finlay JA, et al. Molecular forms of prostate-specific antigen and the human kalikrein gene family: a new era. Urol 1995;45:729-44.
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