Elsevier

Urology

Volume 53, Issue 1, January 1999, Pages 155-160
Urology

Adult Urology
Rapid detection of elevated prostate-specific antigen levels in blood: performance of various membrane strip tests compared1

https://doi.org/10.1016/S0090-4295(98)00419-1Get rights and content

Abstract

Objectives. To compare the ability of four commercially available membrane strip tests to detect increased (4 μg/L or more) concentrations of prostate-specific antigen (PSA) in blood.

Methods. Serum samples with PSA concentrations less than 4 μg/L (n = 67) and from greater than 4 μg/L to 20 μg/L (n = 32) were independently examined by two observers using the PSA membrane strip tests from Chembio, Medpro, Seratec, and Syntron. The positive and negative results of each membrane strip test were classified as either true positive or negative and false negative or positive by comparing them with the quantitative PSA assay of Immulite DPC using the conventional threshold value of 4 μg/L.

Results. The interobserver variations of the tests were between 93% and 97%. The color stability of the Seratec and Chembio tests did not show significant differences between test results read within 10 to 20 minutes of the reaction time; however, the results of the other two tests were especially affected by variations in the reading time. The sensitivity and specificity of the tests in relation to the threshold of 4 μg/L were 67% to 93% and 87% to 97%, respectively.

Conclusions. The Syntron test and, within certain limitations, the Seratec test fulfill the concept of a rapid and convenient PSA determination to detect PSA concentrations greater than 4 μg/L. Methodologic optimization of the tests by a grading of the PSA measuring ranges (eg, between 0 and 2, 3 and 4, 4 and 6, and 7 and 10 μg/L) should be taken into account for future development.

Section snippets

Samples

Serum specimens from 99 white men were examined. All men were investigated in the Department of Urology at the University Hospital Charité or the affiliated outpatient department and were classified in one of three groups. Thirty-three men (median age 59 years, range 33 to 88), including healthy men and patients hospitalized in our department or attending our outpatient department because of nonprostatic disease (erectile dysfunction, stone disease without obstruction, and infection) and with a

Reading time, interobserver variation, and negative control samples

The instruction sheets advise the user to read the results after 5 minutes (Syntron), not later than 10 minutes (Medpro), at 10 minutes (Seratec), and within 12 to 15 minutes (Chembio). To test the influence of reading time on the results, all tests were read minute by minute 5 minutes before and after the reading time indicated in the instructions. The test results of Medpro and Syntron were especially influenced by the reading time of the test. For example, reading 1 or 2 minutes earlier

Comment

PSA is prostate tissue specific and increases under numerous common prostate conditions such as benign prostatic hyperplasia, prostatitis, and prostate cancer.1 Thus, an increased serum PSA does not always correspond to prostate cancer but rather indicates an abnormality of the prostate and the need for further evaluation. A PSA value of 4 μg/L is generally considered the cutoff point, although only 30% of patients with PSA concentrations between 4 and 10 μg/L had cancer detected by biopsy. By

Acknowledgements

To the producers and distributors of the membrane test strips for supplying test kits free of charge.

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1

This study includes parts of the doctoral thesis of Jürgen Zachow.

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