"Delfia" and "Amerlite": two sensitive nonisotopic immunoassay systems for assay of thyrotropin compared.

Abstract We assessed the LKB "Delfia" (time-resolved dissociation-enhanced lanthanide fluoroimmunoassay) and the Amersham "Amerlite" (enhanced luminescent immunometry) assays of thyrotropin in serum. Both assays are sensitive (respective detection limits: 0.02 and 0.04 milli-int. unit/L) and have very good within- and between-batch precision over a wide range of thyrotropin concentrations. Results by the two methods correlate well (r = 0.992); the regression equation is: Amerlite = 0.915 Delfia - 0.33 milli-int. unit/L. The standard curve for the Delfia assay was linear, but that for the Amerlite assay showed some deviation from linearity below 0.5 milli-int. unit/L. Both assays have a negative bias in comparison with radiolabeled immunoradiometric assays, as judged by results for samples from the Quality Assurance Scheme. Both assays discriminate well between hyper-, hypo-, and euthyroid subjects, and results for thyrotropin for most patients with nonthyroidal illness were within the euthyroid reference interval. Both assays are convenient to perform and are based on systems that provide a viable alternative to radioimmunoassay.</jats:p

Six methods for urinary protein compared.

Abstract Six assays for protein in urine were compared for linearity, ease of standardization, precision, comparability of assay values, technical ease of assay, and current cost. The assays investigated were three dye-binding techniques, a recent turbidimetric technique, the trichloroacetic acid--biuret reaction, and a tannic acid protein precipitation reaction with ferric chloride. All assays suffered from standardization problems, although the biuret method showed the best analytical recovery of albumin and gamma-globulin. The tannic acid/ferric chloride method is dependent on sample pH. The turbidimetric assay exhibited the greatest imprecision; i.e., CVs were 19.5% at a protein concentration of 0.13 g/L and 6.0% at a protein concentration of 1.3 g/L. On the basis of all the factors assessed, we conclude that the Pesce/Strande Ponceau-S and the Bio-Rad Coomassie Brilliant Blue dye-binding techniques offer certain advantages over the other assays studied.</jats:p

Immunological and colorimetric determination of prostatic acid phosphatase--technical and clinical reappraisal in symptomatic patients.

Abstract We compared a selection of quantitative immunological methods for prostatic acid phosphatase (PAP) with routine colorimetric assays for total and tartrate-labile acid phosphatase and evaluated their relative clinical merits in the differential diagnosis of prostatic carcinoma. We also assessed a wide range of commercial control materials for suitability of use with these methods. Patients studied included 111 cases of prostatic carcinoma, 42 cases of benign prostatic hyperplasia, and 33 controls. The principles of the methods used included determination of enzymatic activity using p-nitrophenyl phosphate, RIA, immunoradiometric, and enzymoimmunometric assays. Performance characteristics for the immunological methods were inferior to manufacturers' precision and specificity claims. We identified control materials that were unsuitable for routine use. Poor discrimination between clinical groups was observed for all methods. Analysis by use of a receiver operator characteristic plot failed to improve this. We conclude that the immunological methods we studied offer no advantages over colorimetric methods in the differential diagnosis of prostatic cancer in symptomatic patients.</jats:p