Specimen:

Plasma

Collection Medium:

Alternate
Collection Media:

Call laboratory for additional acceptable specimen collection 
containers.

Minimum:

2 mls whole blood in light green top tube

Testing
Schedule:

24 hrs/day, 7 days a week, including holidays.

Analytic Time:

2 hours (upon receipt in laboratory)

Reference Range:

No accepted reference range.  There is an increased probability of 
prostate cancer with lower %FPSA.

Comments:

Tests done on Wednesdays.  For additional services, contact Clinical 
Pathology Resident on-call at pager #3404.

Prostate-specific antigen (PSA) is a glycoprotein (molecular weight 
30,000-34,000 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 4-10 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.

The free PSA immunoassay is indicated for measurement of fPSA in 
conjunction with the total PSA assay to develop a ratio of fPSA to tPSA 
(%fPSA). This ratio is useful when used in conjunction with the Total 
PSA test as an aid in distinguishing prostate cancer from benign 
prostatic conditions in men age 50 years or older who have a digital 
rectal examination (DRE) that is not suspicious for prostate cancer and 
an total PSA value in the range 4-10 ng/ml. Prostate biopsy is required 
for the diagnosis of prostate cancer. The electrochemiluminescence 
immunoassay "ECLIA" is intended for use on the Roche Elecsys 1010 and 
2010 immunoassay analyzers.

Please print, complete and submit the Advance Beneficiary Notice 
(ABN) along with the Laboratory Requisition before shipping the 
specimen.

Test
Limitations:

The assay is unaffected by indexes of icterus <65 mg/dl, hemolysis 
<1000, lipemia <1500 mg/dl and biotin < 60 ng/ml. In patients receiving 
therapy with high biotin doses (i.e. > 5mg/day) no sample should be 
taken until at least 8 hours after the last biotin administration.

In vitro tests were performed on 28 commonly used pharmaceuticals. Only 
flutamide at therapeutic daily dosage levels resulted in slightly 
depressed free PSA values.

As with all tests containing monoclonal mouse antibodies, erroneous 
findings may be obtained from samples taken from patients who have been 
treated with monoclonal mouse antibodies or have received them for 
diagnostic purposes. Free PSA contains additives which minimize these 
effects.

In rare cases, interference due to extremely high titers of antibodies 
to streptavidin can occur.

There is no high-dose hook effect for free PSA concentrations up to 
15,000 ng/ml.

No influence was observed from rheumatoid factor (up to 1500 U/ml).

For diagnostic purposes, the Elecsys free PSA findings should always be 
assessed in conjunction with the patient's medical history, clinical 
examination and other findings.

Methodology:

Electrochemiluminescence Immunoassay

Sample
Processing:

Centrifuge at 3000 RPM for 10 minutes.
Aliquot plasma into labeled container and cap.

Sample
Storage:

Refrigerate.

Transport
Instructions:

Place specimen into zip-lock type bag, seal bag.
Place requisition into outside pocket of bag.
Transport in cooler with refrigerated coolant packs.

CPT Code:

84154