Quantitative (FIA) and Qualitative (Colloidal Gold) Detection of Prostate-Specific Antigen in Serum, Plasma, or Whole Blood
Prostate-Specific Antigen (PSA) is a serine protease produced by prostate epithelial cells and secreted into seminal plasma — first identified as a semen component by Hara et al. in 1971, and subsequently isolated as a 34 kDa serine protease from prostate tissue by Wang et al. in 1979. PSA is one of the few truly organ-specific tumor markers, with a detection rate of 70–90% in prostate cancer cases, making PSA measurement a cornerstone of prostate disease monitoring and auxiliary assessment.
After radical prostatectomy, PSA concentrations typically decline to near-undetectable levels. If PSA fails to decline, or begins rising again after an initial decline, tumor metastasis or recurrence should be suspected. Because elevated PSA can also occur in benign conditions such as prostatic hyperplasia, prostatitis, and other urogenital disease, PSA results must always be interpreted together with clinical findings and other diagnostic tests — not as a standalone signal.
Different clinical settings need different PSA outputs. Sekbio therefore supplies PSA rapid tests in two formats: the PSA Rapid Quantitative Test Kit (SEK-F032), an instrument-read fluorescence immunoassay (FIA) that reports a precise numeric PSA concentration for tracking trends over time; and the PSA Rapid Test Kit, Colloidal Gold (SEK-G025), an instrument-free, visually read qualitative lateral flow test for fast Positive/Negative screening aid at the point of care.
Both formats detect PSA in whole blood, serum, or plasma using a double-antibody sandwich immunoassay. Here is how they differ.
| Attribute | Quantitative FIA — SEK-F032 | Qualitative Colloidal Gold — SEK-G025 |
|---|---|---|
| Result type | Numeric PSA concentration (ng/mL) | Positive / Negative / Invalid (visual read) |
| Instrument required | Yes — Sekbio Immunofluorescence Analyzer | No — read by eye |
| Specimen | Whole blood, serum, or plasma | Serum, plasma, or whole blood (venipuncture or fingerstick) |
| Sample volume | 35 µL specimen (100 µL mixed sample loaded) | 50 µL specimen + 40 µL buffer |
| Time to result | 15 minutes | 5 minutes (do not read after 10 minutes) |
| Reported performance | Linearity r ≥ 0.9900, accuracy ±15%, CV ≤ 15% (vs. Roche Elecsys total PSA) | 98.9% sensitivity, 98.7% specificity, 98.8% accuracy (vs. commercial PSA EIA) |
| High-dose hook effect | None observed up to 200 ng/mL | Possible above ~100 ng/mL — dilution retest protocol available |
| Shelf life | 24 months | 18 months |
| Best fit | Serial monitoring, treatment-response trend tracking | Fast, instrument-free auxiliary aid at the point of care |
The Sekbio PSA Rapid Quantitative Test Kit (SEK-F032) is a fluorescence immunochromatographic assay (FIA) that quantitatively measures PSA concentration in human whole blood, serum, or plasma. The kit uses a double-antibody sandwich format: fluorescent microsphere-labeled mouse anti-PSA antibody is pre-loaded on the conjugate pad, and mouse anti-PSA antibody is pre-coated on the test line, with goat anti-rabbit IgG antibody on the control line for internal control.
As the sample migrates along the nitrocellulose membrane, PSA forms a fluorescent sandwich complex at the test line. The Sekbio Immunofluorescence Analyzer reads the test-line signal and converts it into a numeric PSA concentration (XX.XX ng/mL) using a calibration curve embedded directly in the reagent's ID chip — no manual calibration curve entry required.
SEK-F032 is intended for the dynamic monitoring of patients with malignant tumors, assisting clinicians in evaluating disease progression or treatment efficacy. It is not intended for early diagnosis or definitive diagnosis of malignancy, and is not suitable for prostate cancer screening in the general population. A single PSA value carries limited meaning on its own — the trend over successive measurements, read alongside prior treatment history, is what supports clinical decisions.
Equilibrate the reagent, ID chip, and specimen to room temperature before starting.
Power on the Sekbio Immunofluorescence Analyzer, select the test mode and sample type, and read the reagent's ID chip. Tear open the foil pouch and lay the test card flat — use within 60 minutes of opening.
Draw 35 µL of serum, plasma, or whole blood, add it to the sample diluent, and mix for 60 seconds. Pipette 100 µL of the mixed sample into the test card's sample well.
In Standard Test mode, insert the card immediately and let the analyzer time and read automatically. In Quick Test mode, time 15 minutes first, then insert the card for immediate reading. Cards not read within 15 minutes are invalid.
The analyzer displays a numeric PSA concentration directly on screen — no visual band reading is required.
Result falls within the 2.0–80.0 ng/mL analytical range and is reported as a precise numeric value. Compare against the patient's prior PSA values and the local reference interval.
PSA concentration is below the assay's detection limit. Consistent with a well-controlled or undetectable PSA state; interpret against the reference interval and treatment history.
PSA concentration exceeds the assay's upper analytical limit. Consider specimen dilution or confirmatory testing per your laboratory's protocol.
Results in the 2.0–2.5 ng/mL or 80.0–100.0 ng/mL ranges carry an elevated risk of inaccuracy. No hook effect occurs up to 200 ng/mL. If sample loading is insufficient, the analyzer displays "No sample loading or insufficient sample loading" — discard the card and retest with a new one.
Materials required but not provided: Sekbio Immunofluorescence Analyzer, transfer pipette, specimen collection containers, centrifuge (serum/plasma only), timer.
The Sekbio PSA Rapid Test Kit, Colloidal Gold (SEK-G025) is a rapid, visually read, qualitative lateral flow immunoassay for PSA in human serum, plasma, or whole blood. It uses the same double-antibody sandwich principle as the quantitative kit — mouse anti-PSA monoclonal antibody on the test line (T) and goat anti-rabbit IgG on the control line (C), with colloidal gold-labeled anti-PSA antibody and rabbit IgG on the conjugate pad — but requires no instrument: results are read by eye as Positive, Negative, or Invalid.
When PSA is present, it binds gold-labeled anti-PSA antibody and migrates to the test line, producing a visible red band; any shade of color at the test line is considered positive. The control line always develops when the test has run correctly, confirming sample flow and reagent integrity — regardless of the PSA result.
SEK-G025 is intended as an aid in the auxiliary diagnosis and monitoring of prostate-related conditions, particularly prostate cancer, helping evaluate PSA status in male patients. It is not intended for use as a screening test in the general population and should not be used as the sole basis for a diagnosis. Elevated PSA can also be associated with benign prostatic hyperplasia (BPH), prostatitis, and other non-malignant conditions — a positive result should always be confirmed with other clinical and laboratory findings.
Equilibrate the test device, specimen, and buffer to room temperature (15–30°C) before testing. Use the test device within 1 hour of opening the foil pouch.
Remove the test device from its pouch and place it on a clean, flat, dry surface. Use immediately for optimal results.
Transfer 50 µL of serum, plasma, or whole blood (venipuncture or fingerstick) into the sample well (S), then add 40 µL of buffer and start the timer.
Wait for colored line(s) to appear and interpret the result at 5 minutes. Do not interpret after 10 minutes — results may be unreliable.
Any visible color in the Test line (T) region is a positive result, regardless of intensity.
Both C and T bands appear. PSA detected at or above the assay's cutoff. Confirm with other clinical and laboratory findings — do not diagnose on this result alone.
Only C band appears. PSA not detected above the assay's cutoff. Does not rule out prostate disease — PSA may be undetectable in early stages, and very high PSA (typically >100 ng/mL) can cause a hook-effect false negative.
No C band appears, regardless of T-line status. Discard the result, review the procedure, and repeat with a new test. If the problem persists, contact your local distributor.
In suspected high-dose hook effect (clinically obvious prostate findings with a negative result), retest using the kit's sample diluent at a 1:10 dilution, then 1:100 if clinical suspicion remains and the result is still negative.
Evaluated against a commercial PSA EIA as the comparison method.
| Metric | Result | 95% Confidence Interval |
|---|---|---|
| Relative Sensitivity | 98.9% | 95.4–99.8% |
| Relative Specificity | 98.7% | 96.3–99.6% |
| Accuracy | 98.8% | 97.0–99.5% |
| Intra-assay precision | 98% reproducibility across 3 runs, 3 lots, at PSA levels 0, 3, and 10 ng/mL | |
| Inter-assay precision | 98% reproducibility across 3 independent assays | |
Materials required but not provided: specimen collection containers, centrifuge (for serum/plasma preparation), timer or stopwatch, disposable gloves and protective equipment.
Stock the quantitative FIA (SEK-F032) for serial trend monitoring and the qualitative colloidal gold kit (SEK-G025) for fast, instrument-free triage — both from the same ISO 13485-certified manufacturing line.
Both formats are validated for whole blood, serum, and plasma; common anticoagulants (heparin sodium, EDTA, sodium citrate) do not affect results.
SEK-G025 reads in 5 minutes with no instrument; SEK-F032 delivers a lab-comparable numeric result in 15 minutes via the Sekbio Immunofluorescence Analyzer.
Both kits store at 2°C–30°C with no cold-chain requirement — 24 months shelf life for SEK-F032, 18 months for SEK-G025.
Both formats are manufactured under ISO 13485-certified quality management and CE marked for IVD use, with full technical documentation available for regulatory registration.
Custom branding on cassettes/cards and cartons, multilingual IFU printing, and packaging design available for either format. Contact Sekbio for volume-based OEM pricing.
PSA should decline to near-undetectable levels after radical prostatectomy. Serial quantitative testing with SEK-F032 supports timely detection of biochemical recurrence — defined by PSA persistence or two consecutive rises above the post-surgical nadir.
Following radiotherapy, PSA nadir plus 2 ng/mL (the Phoenix definition) is a widely used criterion for treatment failure. For androgen deprivation therapy or chemotherapy, serial PSA trends with SEK-F032 help track treatment response.
SEK-G025 gives urology and primary care clinics a fast, visually read auxiliary aid for evaluating PSA status during a routine visit, without needing to send samples to a central laboratory or invest in analyzer hardware.
Room-temperature stability, no equipment requirement, and fingerstick whole blood compatibility make SEK-G025 practical for clinics and outreach settings where laboratory access or instrumentation is limited.
Sekbio supplies the PSA Rapid Test in two formats. The PSA Rapid Quantitative Test Kit (SEK-F032) is a fluorescence immunochromatographic assay (FIA) that reports a numeric PSA concentration in ng/mL using the Sekbio Immunofluorescence Analyzer, with results in 15 minutes. The PSA Rapid Test Kit, Colloidal Gold (SEK-G025) is a visually read, qualitative lateral flow immunoassay requiring no instrument, with results in 5 minutes. Both use a double-antibody sandwich format and detect PSA in human whole blood, serum, or plasma.
PSA is a serine protease produced by prostate epithelial cells and secreted into seminal plasma — first identified by Hara et al. in 1971 and isolated from prostate tissue by Wang et al. in 1979. PSA is one of the few truly organ-specific tumor markers, detectable in 70–90% of prostate cancer cases. After prostatectomy, PSA typically declines to near-undetectable levels; if PSA fails to decline, or rises again after an initial decline, tumor recurrence or metastasis should be suspected. Elevated PSA can also occur in benign conditions such as prostatic hyperplasia and prostatitis, so PSA results must always be interpreted alongside clinical findings.
The quantitative kit (SEK-F032) requires the Sekbio Immunofluorescence Analyzer and reports a precise numeric PSA value (2.0–80.0 ng/mL analytical range), making it suited to tracking PSA trends over time — for example after prostatectomy or during systemic therapy. The qualitative kit (SEK-G025) needs no instrument, is read visually as Positive, Negative, or Invalid within 5–10 minutes, and is validated at 98.8% accuracy against a commercial PSA EIA — suited to fast, low-infrastructure point-of-care use where a numeric trend value is not required. Many customers stock both: qualitative for rapid triage, quantitative for serial monitoring.
No. SEK-F032 is intended for the dynamic monitoring of patients already diagnosed with malignant tumors — assisting clinicians in evaluating disease progression or treatment efficacy over time. It is not intended for early diagnosis or definitive diagnosis of malignancy, and is not suitable for prostate cancer screening in the general population. A single PSA value should never be interpreted in isolation; the clinically meaningful signal is the trend over time, read together with prior treatment history and other diagnostic findings.
SEK-G025 is intended as an aid in the auxiliary diagnosis and monitoring of prostate-related conditions, particularly prostate cancer — it helps evaluate PSA status in male patients but must not be used as the sole basis for a diagnosis. Like the quantitative kit, it is not intended for use as a screening test in the general population. Elevated PSA on either kit can also reflect benign prostatic hyperplasia (BPH), prostatitis, or other non-malignant conditions, so a positive result should always be confirmed with other clinical and laboratory findings.
SEK-F032 (quantitative): 35 µL of whole blood, serum, or plasma is mixed with sample diluent for 60 seconds, and 100 µL of the mixed sample is loaded into the test card; the analyzer reads the result at 15 minutes. SEK-G025 (qualitative): 50 µL of serum, plasma, or whole blood (venipuncture or fingerstick) is added to the sample well followed by 40 µL of buffer; results are read visually at 5 minutes and must not be interpreted after 10 minutes. Common anticoagulants (EDTA, heparin, sodium citrate) are compatible with both kits.
SEK-F032's analytical detection range is 2.0–80.0 ng/mL, with linear correlation coefficient (r) ≥ 0.9900, accuracy within ±15%, detection limit ≤ 2.0 ng/mL, and within-run/between-run precision (CV) ≤ 15%. Results below 2.0 ng/mL are reported as "<2.0 ng/mL"; results above 80.0 ng/mL are reported as ">80.0 ng/mL". The kit's built-in reference interval is 0–4.0 ng/mL; each laboratory should establish a locally validated reference interval given variation by geography, ethnicity, and age.
SEK-G025 was evaluated against a commercial PSA EIA reference method, with relative sensitivity of 98.9% (95% CI: 95.4–99.8%), relative specificity of 98.7% (95% CI: 96.3–99.6%), and overall accuracy of 98.8% (95% CI: 97.0–99.5%). Precision testing showed 98% intra-assay reproducibility across 3 runs, 3 lots, and PSA levels of 0, 3, and 10 ng/mL, and 98% inter-assay reproducibility across 3 independent assays.
The high-dose hook effect occurs when extremely high antigen concentrations saturate both capture and detection antibodies, producing a falsely low or negative result. On SEK-F032, no hook effect occurs up to 200 ng/mL PSA. On SEK-G025, hook effect may occur above approximately 100 ng/mL; if a patient has clinically obvious prostate findings but a negative result, the IFU recommends retesting with the sample diluent at a 1:10 dilution, and further to 1:100 if clinical suspicion remains and the result is still negative.
Yes. Hematocrit affects fluorescence-based whole blood results on SEK-F032, and the reported result is already corrected and compensated for typical whole blood samples. When hematocrit deviates by more than 40%, the IFU provides a correction formula — C1 = 0.625 × C0 / (1 − P), where C0 is the uncorrected result and P is the hematocrit fraction — or an equivalent correction-coefficient table, so the corrected value C1 can be used as the final result.
Both kits store at 2°C–30°C in a dry location protected from light and must not be frozen. SEK-F032 (quantitative FIA) has a 24-month shelf life and the test card must be used within 60 minutes of opening the foil pouch. SEK-G025 (qualitative colloidal gold) has an 18-month shelf life and should ideally be used within 1 hour of opening. Manufacture and expiration dates are printed on each kit's label.
Yes. Sekbio offers full OEM and private label services for both the quantitative (SEK-F032) and qualitative (SEK-G025) PSA Rapid Test Kits: custom branding on cassettes/cards and outer cartons, multilingual IFU printing, and custom packaging design. Technical documentation packages for CE marking or local regulatory registration in target markets are available. Contact info@sekbio.com with your target market, format preference, annual volume estimate, and brand requirements for a dedicated OEM quotation.
ISO 13485-certified. CE marked. Quantitative (SEK-F032) and qualitative (SEK-G025) formats available in 25-test kits and bulk OEM supply. Contact Sekbio for pricing, samples, and regulatory documentation.
Sekbio also supplies validated free-PSA monoclonal antibody pairs for CLIA, ELISA, and lateral flow development — affinity-purified, >90% purity Mouse IgG1, available in bulk for OEM IVD manufacturers building their own PSA assays.
View PSA Antibody Pair →Explore Sekbio's full rapid test portfolio — covering infectious disease, cardiac markers, hormones, and oncology biomarkers in colloidal gold and fluorescence lateral flow formats. OEM supply with CE marking documentation support.
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