Electro-chemiluminescence immunoassay (ECLIA) for the quantitative determination of total PSA in

Elecsys® total prostate specific antigen
(total PSA)
Electro-chemiluminescence immunoassay (ECLIA)
for the quantitative determination of total PSA in
human serum and plasma 1
Indication
Prostate-specific antigen (PSA) is a glycoprotein (molecular weight of approximately 34 kD) having a structural relationship to
the glandular kallikreins. It has the function of a serine proteinase and its main role is to liquify semen and to dissolve the c­ ervical
mucous cap, allowing the entry of sperm. The proteolytic activity of PSA in blood is inhibited by the irreversible formation of
­complexes with protease inhibitors such as alpha-1-anti-chymotrypsin (ACT) and others. Approximately 30 % of the PSA ­present in
blood occurs in the free form, but is proteolytically inactive.2
Measurement of total PSA is clinically useful in the following way:
•Elevated concentrations of PSA in serum are generally indicative of a pathologic condition of the prostate like prostatitis, benign
prostate hyperplasia (BPH) or carcinoma.3 By combining PSA determination and digital rectal examination (DRE) the detection
rate of prostate cancer can be increased.
•Although ACT is present in excess in human serum, a high percentage of free PSA (approximately 30 %) can be found in patients
with BPH. Determination of the free/total PSA ratio increases the specificity of PSA.
•Monitoring of progress and efficiency of therapy in patients with prostate carcinoma4 whereby the steepness of the rate of fall in
PSA down to undetectable levels after adequate treatment provides information on the success of therapy.5
•PSA velocity: Prostate volume increases more rapidly in patients with prostate cancer than in patients with BPH. The increase in
PSA per unit of time can be used to determine the growth behavior and differentiation of prostate tissue.6
Test principle: one-step sandwich assay
Streptavidin
microparticle
PSA in the
sample
Ru
Biotinylated
monoclonal
PSA specific
antibody
Ruthenylated
monoclonal PSAspecific antibody
9 min
9 min
Ru
Measurement
Ru
The two monoclonal antibodies used in the Elecsys total PSA are fragmented antibodies to reduce Human-Anti-Mouse­Antibodies (HAMA) interferences and bind to the epitopes 6b and 4b as described in literature.7 The test recognizes PSA
and PSA-ACT on an equimolar basis in the range of 10 - 50 % free PSA/total PSA which are the free PSA-ratios as seen
in clinical practice.8
Elecsys technology
ECL (ElectroChemiLuminescence) is Roche’s technology for immunoassay detection. Based on this technology and combined
with well-designed, specific and sensitive immunoassays, Elecsys delivers reliable results. The development of ECL immunoassays
is based on the use of a ruthenium-complex and tripropylamine (TPA). The chemiluminescence reaction for the detection of the
reaction complex is initiated by applying a voltage to the sample solution resulting in a precisely controlled reaction.
ECL technology can accommodate many immunoassay principles while providing superior performance.
Elecsys® total PSA assay characteristics:
Testing time
Test principle
Traceability
Sample material
Sample volume
Detection limit
Measuring range (low end defined by lower detection limit)
Repeatability
Intermediate precision
Functional sensitivity
Expected values, healthy males
(Results from the multicenter evaluation. Data on file at Roche.)
Order information:
Material
Elecsys® total PSA
Elecsys® total PSA CalSet
PreciControl Tumormarker or
PreciControl Universal
Diluent Universal
References:
1 Butch, A.W., Crary, D., Yee, M. (2001). Analytical performance of the Roche
total and free PSA assays on the Elecsys 2010 immunoanalyzer. Clin. Biochem.;
35, 143-145.
Not for distribution in the USA.
COBAS, COBAS E, ELECSYS and LIFE NEEDS ANSWERS
are trademarks of Roche.
©2011 Roche
Roche Diagnostics Ltd.
CH-6343 Rotkreuz
Switzerland
www.cobas.com
18 min.
One-step sandwich assay
Standardized against the Stanford Reference Standard/WHO 96/670
(90 % PSA-ACT + 10 % free PSA)
Serum, Li-heparin, K 3-EDTA and sodium citrate plasma.
When sodium citrate is used, the results must be corrected by + 10 %
20 µL
0.002 ng/mL (Elecsys® 2010 and cobas e 411 analyzer)
0.003 ng/mL (E 170 and cobas e 601, e 602 modules)
0.002 - 100 ng/mL (Elecsys® 2010 and cobas e 411 analyzer)
0.003 - 100 ng/mL (E 170 and cobas e 601, e 602 modules)
1.8 - 2.5 %
cobas e 601 / e 602 modules, E 170:
2.9 - 4.4 %
Elecsys® 2010 and cobas e 411 analyzers:
1.4 - 3.7 %
cobas e 601 / e 602 modules, E 170:
2.4 - 3.8 %
Elecsys® 2010 and cobas e 411 analyzers:
0.030 ng/mL
Age (years)
Median (ng/mL)
95th percentile (ng/mL)
0.57
1.4
< 40
0.59
2.0
40 - 49
0.75
3.1
50 - 59
1.65
4.1
60 - 69
1.73
4.4
≥ 70
Product configuration
100 tests
200 tests (only for cobas e 601,
e 602 and E 170)
Material number
04641655 190
04491734 190
4 x 1 mL
2 x 3 mL each
2 x 3 mL each
2 x 16 mL sample diluent or
2 x 36 mL sample diluent
04485220 190
11776452 122 or
11731416190
11732277 122 or
03183971 122
2 Zhang, W.M., Leinonen, J., Kalkkinen, N., Dowell, B., Stenman, U.H. (1995). Purification and
Characterization of Different Molecular Forms of Prostate-Specific Antigen in Human Seminal
Fluid. Clin Chem; 41, 1567-1573.
3 Nadler, R.B., Humphrey, P.A., Smith, D.S., Catalona, W.J., Ratliff, T.L. (1995). Effect of inflammation and
benign prostatic hyperplasia on elevated serum prostate specific antigen levels. J. Urol.; 154, 407-13.
4 National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for
Use of Tumor Markers in Testicular, Prostate, Colorectal, Breast, and Ovarian Cancers (2008).
Clin. Chem.; 54, e11-e79.
5 Partin, A.W., Pound, C.R., Clemens, J.Q., Epstein, J.I., Walsh, P.C. (1993). Serum PSA after anatomical radical prostectomy. The Hopkins experience after 10 years. Urol. Clin. North Am.; 20, 713-725.
6 Semjonow, A., Schmid, H.P. (2002). The rise and fall of PSA: clinical implications of prostate
specific antigen kinetics. Urol. Res.; 30, 85-88.
7 ISOBM TD-3 International Workshop on Monoclonal Antibodies against PSA (1999).
Tumor Biology; 20, Suppl. 1.
8 Roddam, A.W., Rimmer, J., Nickerson, C., Ward, A.M. (2006). Prostate-specific antigen: bias and
molarity of commercial assays for PSA in use in England. Ann Clin Biochem; 43, 35-48.