Microparticle immunoenzymatic assay for detection of prostate specific antigen: characterization of the technique and comparative analysis with a monoclonal immunoradiometric assay.

Microparticle immunoenzymatic assay (MEIA) is a new, ultrasensitive technique recently introduced for detection of prostatic specific antigen (PSA). It is easily performed, totally automated, and cheaper and faster than radioimmunometric techniques. In this study, the levels of PSA in 194 males with urologic problems and healthy males, recorded by microparticle monoclonal ultrasensitive enzymoimmunoassay (MEIA) and immunoradiometric assay (IRMA), are comparatively evaluated. Variables recorded were age of patient, size and weight of the prostate, and PSA levels analyzed by the MEIA (MEIA-PSA) and IRMA (ELSA-PSA) techniques. Different determinations of PSA were performed in order to calculate the intra- and interassay variation coefficient for the MEIA-PSA assay. Means of prostatic length, width, and depth, recorded by ultrasonography, were 28.3, 35.8, and 31.4 mm, respectively, with a mean prostatic size of 19 ml and a mean prostatic weight of 23.9 g. Mean IRMA-PSA was 4.53 ng/ml and mean MEIA-PSA was 2.04 ng/ml. The difference between them was 2.49, and the ratio IRMA-PSA:MEIA-PSA was 3.17. Interassay and intraassay variation coefficients for MEIA-PSA were 6.58 and 9.96%, respectively. MEIA-PSA values correlated linearly with the age of the patients (r = 0.65, p = 0.0001), size of the prostate (r = 0.71, p = 0.0001), weight of the prostate (r = 0.71, p = 0.0001), and the value of IRMA-PSA (r = 0.80, p = 0.0001). Paired t tests showed that the values of PSA measured by MEIA and IRMA are statistically different (p = 0.0001), with independence of the level of PSA considered.

[A comparative analysis of monoclonal assays for the determination of PSA: radioimmunometric assay (ELSA) vs microparticle immunoenzyme assay (MEIA)]. / Análisis comparativo de dos ensayos monoclonales para la determinación de PSA: ensayo radioinmunométrico (ELSA) vs ensayo inmunoenzimático de micropartículas (MEIA).

Comparative analysis of PSA values measured by MEIA and ELSA techniques in a group of 70 unselected patients. A good correlation was observed between PSA levels determined by ELSA-PSA immunoradiometric techniques and those obtained by MEIA-PSA (r = 0.93, p < 0.00001). However, ELSA-PSA values have been 1.73 +/- 0.1 times higher than those by MEIA-PSA. A mean-paired comparison indicates that PSA mean levels (0.48 +/- 0.07 and 0.29 +/- 0.05 for ELSA and MEIA, respectively) are significantly different and define two groups of nonhomogeneous values (p < 0.0001). The same results are obtained when patients with PSA values higher and lower than 4 ng/ml are analyzed separately. For patients with PSA lower than 1 ng/ml, the difference between mean ELSA-PSA and MEIA-PSA values disappears; 0.74 +/- 0.08 vs 0.62 +/- 0.05, respectively (p > 0.1). In this group, the results from both assays are statistically consistent. When considering the group of patients with PSA < 1 ng/ml, no difference between both techniques becomes apparent, which seems to indicate the absence of differences in sensitivity between both techniques when considering low levels of serum PSA. Nevertheless, it is clear that the results from these techniques can not overlap and are not comparable and so, to all practical effects, it is recommended that follow-up of any particular patient is made always with the same technique and even at the same laboratory.

[Undescended testicle treated with FSH and HCG]. / Tratamiento médico del testículo no descendido con FSH y HCG.

Medical treatment with FSH and HCG was tested during 21 days in 47 cases (76 testis) of undescended testis. The average testis size, as measured by ecography, increased from 0.828 cc to 1.57 cc 48 hours after completing the treatment. Three months later the average testis size was 1.025 cc and 1.24 cc at six months. FSH increased slightly and total testosterone and free testosterone increased significantly. After treatment, 68% of the previously undescended testis descended.