Free PSA in Human Serum with Roche e801
Detection of Free PSA in Human Serum with Roche e801
|Test Name:||Immunoassay for the in vitro quantitative determination of free prostate-specific antigen in human serum and plasma. This immunoassay is indicated for measurement of fPSA in conjunction with the Elecsys total PSA assay to develop a ratio (% fPSA) of fPSA to tPSA.|
|Method Name:||In the Elecsys FPSA assay an FPSA specific antibody labeled with a ruthenium complex is used to determine the free prostate specific antigen concentration.|
|Results:||Technical Range: 0.018-50 ng/mL
Reportable Range: 0.02-44.4 ng/mL
|Free:Total PSA ratio||50-59 years||60-69 years||70 years and older|
|Clinical Significance:||This immunoassay is indicated for measurement of fPSA in conjunction with the Elecsys total PSA assay to develop a ratio (% fPSA) of fPSA to tPSA. This ratio is useful when used in conjunction with the Elecsys total PSA test as an aid in distinguishing prostate cancer from benign prostatic conditions in men aged 50 years or older who have a digital rectal examination (DRE) that is not suspicious for prostate cancer and an Elecsys total PSA value in the range 4.00 ng/mL to 10.0 ng/mL. Prostate biopsy is required for the diagnosis of prostate cancer.
Prostate‑specific antigen (PSA) is a glycoprotein (molecular weight 30000‑34000 daltons) having a close structural relationship to glandular kallikrein. It has the function of a serine protease.
The proteolytic activity of PSA in blood is inhibited by the irreversible formation of complexes with proteinase inhibitors such as alpha 1 antichymotrypsin, alpha 2 macroglobulin and other acute phase proteins. In addition to being present in these complexes, PSA is also present in blood in the free form but is proteolytically inactive.
PSA tests lack sufficient sensitivity and specificity to be considered ideal or absolutely diagnostic for screening or early detection because PSA is not specific for prostate cancer. PSA is organ specific, being produced primarily by prostatic secretory epithelium, but has long been known to be elevated in non malignant conditions such as benign prostatic hyperplasia (BPH). A number of studies have found that the % free PSA was significantly lower in patients having prostate cancer than those with benign disease or normal controls. The ratio fPSA/tPSA has been demonstrated to improve the sensitivity and specificity in patients with tPSA values in the “gray zone” of 4.00 10.0 ng/mL.
An equimolar tPSA determination is the prerequisite for reliable ratios. In patients receiving therapy, particularly hormone withdrawal therapy, the fPSA/tPSA ratio cannot be utilized to differentiate prostate hyperplasia from cancer of the prostate. Combining tests from different manufacturers to determine tPSA and fPSA can produce erroneous values, since total PSA tests may be standardized by differing methods or detect free PSA to differing degrees.
|Submission Criteria:||For specimen collection and preparation, only use suitable tubes or collection containers.
Only the specimens listed below were tested and found acceptable.
Plasma: Li-heparin and K2-EDTA plasma
Do not use fluoride plasma
The sample types listed were tested with a selection of sample collection tubes that were commercially available at the time of testing, therefore not all available tubes of all manufacturers were tested. Sample collection systems from various manufacturers may contain differing materials which could affect the test results in some cases. When processing samples in primary tubes (sample collection systems), follow the instructions of the tube manufacturer.
|Rejection Criteria:||Rejection criteria include but are not limited to:
1. Specimens containing fibrin or clots.
2. Excessive platelet clumping
3. Leaking specimens
4. Substandard mixing or collection
5. Expired or improperly stored collection tubes.
6. Improperly filled tubes based on collection tube manufacturer’s guidelines.
7. Contaminated specimens (IV fluid, foreign particles, etc.)
8. Specimens not analyzed within the appropriate time frame.
9. Samples not shipped at appropriate temperature.
10. Samples without 2 proper identifiers or samples having identifiers that do not match the electronic or paper lab requisition.
|Authorization:||Diagnostic testing can only be performed with approval from an authorized provider/agency.|
|Turn Around Time:||1 day.|