Home
HelpEpic Test Code LAB3842 Prostatic Antigen (PSA), with Reflexive Free PSA Screening
Performing Location(s)
BMC
Specimen Type
Serum
Preferred Container
Gold or Red top tube
Blood Tube Draw Volume
Min 50% draw volume
Minimum Volume to Submit for Testing
2 mL Serum
Transportation Needs
| *Does not need to be sent from outreach sites frozen, can be sent spun and refrigerated in primary tube |
Deliver specimen to laboratory within 1 hour of collection if unspun. If not possible see "storage Requirements".
Storage Requirements
Sample tubes should be centrifuged within 2 hour of collection followed by transfer of the serum (red) to a labeled plastic, aliquot tube.
Gold tops do not need to be aliquoted
See Causes of Rejection for temperature requirements.
Causes for Rejection
Mislabeled or unlabeled specimen
Less than 50% draw for Vacutainer tubes
>5 months Refrigerated
> 3 hours Room Temperature
> 5 months Frozen
Hemolysis > 500 mg/dL HgB
Lipemia > 1500 mg/dL Trig
Bilirubin > 20 mg/dL Bili
EDTA,Heparin,NaF, Oxalate
TP <4.2 or >12.1 g/dL
Limitations
The concentration of PSA in a given specimen determined with assays from different manufacturers can vary due to differences in assay methods and reagent specificity. Values obtained with different assay methods cannot be used interchangeably. If, in the course of monitoring a patient, the assay method used for determining serially PSA levels is changed, additional sequential testing should be carried out.
SA levels may be lower in patients who receive hormonal therapy and may not adequately reflect the presence of residual or recurrent disease.
One step sandwich immunometric assays are susceptible to a high-dose “hook effect”, where an excess of antigen prevents simultaneous binding of the capture and detection antibodies to a single analyte molecule. The PSA method shows no hook effect up to 50,000 ng/mL[µg/L].
TPSA levels may be lower in patient who receive hormonal therapy and may not adequetly reflect residual or recurrent disease.
Patient samples may contain heterophilic antibodies that could react in immunoassays to give falsely elevated or depressed results. This assay has been designed to minimize interference from heterophilic antibodies, but complete elimination of this interferent is not guaranteed.
Free PSA is only stable for 24 hours at 4° Celsius. Total and Free PSA stable up to 3 freeze/thaw cycles.
Reference Values
| Interpretation of Total and Free PSA Results | ||||
|
Probability (%) of Detecting Prostate Cancer: |
||||
|
Total PSA Reference Range: 0.1 - 4.0 ng/mL |
||||
| @Total PSA ... | and %Free PSA of ... | the %Probabality of Detecting Prostate Cancer for Age Group | ||
| 50-59 | 60-69 | 70+ | ||
| 4.0-10.0 ng/mL |
Less than or |
45.3 |
58.0 |
70.3 |
|
11 – 19% |
22.5 |
30.3 |
38.0 |
|
|
Greater than or |
0.0 |
25.0 |
28.3 |
|
|
Prostate Cancer Prevalence (%): |
30.3 |
37.2 |
42.9 |
|
Reflex Testing
If the Total Prostatic Antigen (PSA) is less than 4.0ng/mL, no further testing will be performed; only CPT 84153 will be billed.
If the Total Prostatic Antigen (PSA) is greater than 10.0ng/mL, no further testing will be performed; only CPT 84153 will be billed.
If the Total Prostatic Antigen (PSA) is greater than 4.0ng/mL and is less than 10.0ng/mL, a Free PSA will be performed and the %Free PSA will be calculated; CPT’s 84153 and 84154 will be billed.
Days of Analysis
All
Available STAT
No
Includes
Total PSA and (if reflexive criteria is met, see below) Free PSA and % Free PSA
Methodology
Beckman AU/Dx Series
CPT Code
See Reflex Testing
Last Updated
29-NOV-24 MS
Additional Information
Prostate specific antigen (PSA) is a serine protease of approximately 30,000 Daltons produced by the epithelial cells of the prostate gland. The level of PSA in serum and other tissues is normally very low. In malignant prostate disease (prostatic adenocarcinoma) and in non-malignant disorders such as benign prostate hypertrophy (BPH) and prostatitis, the serum level of PSA may become elevated.
Most of the PSA protein in serum is complexed with either a1-antichymotrypsin (ACT) or a 2-macroglobulin.4,5 The PSA protein associated with a 2-macroglobulin is encapsulated and unavailable for measurement by current immunoassay systems. About 90% of the PSA in serum exists as PSA-ACT complex and 10% is free.
The PSA Screening assay measures both the free and the ACT bound components of serum PSA.
The Free PSA assay measures the free components of serum PSA.
Measurement of free PSA helps to discriminate between prostate cancer and benign prostatic diseases. The percentage of free PSA is lower in patients with prostate cancer.
Contraindications:
Massage of the prostate within 48 hours before collection of the blood specimen may result in transitory increases in PSA.
Important Information to consider when requesting Prostatic Antigen Testing