Development of a direct fluoroimmunoassay for serum levels of 17-hydroxyprogesterone

Comparison of three methods for 17 alpha-hydroxyprogesterone

We compared the performance of three 17 alpha-hydroxyprogesterone kits: the double antibody method, the coated tube method (ACTIVE), both from Diagnostic Systems Laboratories, Inc. (DSL) and the coated tube method (COAT-A-COUNT) from Diagnostic Products Corporation (DPC). The assay performance of the two DSL kits was very similar in terms of sensitivity, intra- and inter-assay precision, linearity of dilution, recovery, and specificity. We also analyzed 190 samples for 17 alpha-hydroxyprogesterone values using the above three kits. Twenty-three subjects were from prepubertal population (ages 1 month-13 years), thirty subjects were normal adult males (ages 20-53 years) and the remaining subjects were females in different phase of menstrual cycle (n = 40), on oral contraceptives (n = 20), post-menopausal (n = 17), or pregnant women in their first, second, or third trimester (n = 60). In addition to these 60 pregnancy samples, we analyzed serial samples from 3 pregnancies. 17 alpha-OHP levels paralleled the progesterone levels in all three kits. Although there was reasonable correlation between the DPC and the two DSL kits, the 17 alpha-OHP values were found to be significantly higher with DPC kit during the 2nd and 3rd trimester of pregnancy indicating probable interference in the DPC assay by some structurally related steroids present during pregnancy. The DSL assays may be particularly well suited for measuring 17 alpha-OHP levels during pregnancy.

Reversed-phase high-performance liquid chromatographic screening method for serum steroids using retention index and diode-array detection

A multisteroid screening method has been developed based on the use of 1-[4-(2,3-dihydroxypropoxy)phenyl]-1-alkanones as retention index standards and UV absorbance spectra recorded on-line with a diode-array detector using reversed-phase high-performance liquid chromatographic gradient elution with acetonitrile and water. The effect of chromatographic conditions on retention indices of steroids were studied. The method was tentatively applied to profiling of steroids in serum samples.

Measurement of steroid hormones in plasma by isocratic high performance liquid chromatography coupled to radioimmunoassay

The study of steroidal profiles requires simultaneous determinations of various steroid hormones that cannot be appropriately carried out with the conventional routine immunoassays. Moreover, there are several trials for which the assessment of multiple steroids from a single serum sample is mandatory. In this paper we describe a procedure for simultaneously measuring steroid hormones using a unified solid phase extraction which allows the measurement of both unconjugated and conjugated steroids from 1 ml of sample and a combination of HPLC with isocratic elution followed by RIA. The entire procedure was preliminary carried out for the measurement of testosterone, dehydroepiandrosterone and its sulphated conjugate, androstenedione and 17 hydroxyprogesterone. The use of this technique allows precise and accurate measurements of steroid profile with a single serum aliquot and could be helpful in the diagnosis of various form of endocrine disorders.

Chromatography as a reference technique for the determination of clinically important steroids

Chromatographic methods (paper chromatography, thin layer chromatography, high performance liquid chromatography, gas chromatography and gas chromatography-mass spectrometry) for the determination of clinically important steroids in biological specimens are reviewed. The emphasis is on the use of gas chromatography, gas chromatography-mass spectrometry and high performance liquid chromatography as reference rather than routine techniques. Chromatographic methods are compared with colorimetric, fluorimetric and radioimmunoassay procedures in terms of simplicity of operation, cost and ability to analyse large numbers of specimens. The importance of correct specimen collection and storage are discussed. Sample preparation techniques for the various analytical methods are described. These include extraction of free and conjugated steroids from serum, plasma, urine and saliva by solvent partition, with polymer-based resins such as Amberlite XAD-2, DEAE-Sephadex and Sephadex resins bonded with various other function groups and, more recently, with chemically bonded reversed-phase silicas.

Comparison of three different activation methods for coupling antibodies to magnetisable cellulose particles

The periodate and 1,1'-carbonyldiimidazole activation methods were compared with the cyanogen bromide procedure for coupling antibodies to magnetisable cellulose/iron oxide solid-phase particles. Fluoroimmunoassays for quinine, primaquine, normetanephrine and cannabinoids were employed to assess the binding properties of such coupled solid phases. The cyanogen bromide and 1,1'-carbonyldiimidazole methods gave similar products in most cases, while the specific binding capacity of periodate coupled particles was between two and five times lower. Nevertheless, comparable standard curves could be obtained with solid phase coupled by each method. The periodate and 1,1'-carbonyldiimidazole methods are acceptable alternatives, notably for laboratories lacking the facility to handle the toxic cyanogen bromide.

Comparison of separation techniques in radioimmunoassays for 17-hydroxyprogesterone

Separation techniques have been studied in the development of a direct radioimmunoassay to determine levels of 17-hydroxyprogesterone in serum. The same highly specific sheep antiserum was used throughout, together with the same amount of 125I-labelled 17-hydroxyprogesterone to which was added sodium salicylate to eliminate interference by endogenous binding proteins in serum samples. In one approach, dextran-coated charcoal was employed to adsorb the free fraction and, in another, the antibodies were covalently coupled to magnetisable particles. The antiserum was also adsorbed to assay tubes either directly or indirectly through second (double) antibodies. Analytical recovery and specificity were similar irrespective of the separation technique as was the correlation with results obtained by a reference assay. Levels of 17-hydroxyprogesterone in sera from normal adults and from treated and untreated patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency were also similar. However, the assay employing dextran-coated charcoal for separation showed the best precision and resulted in the greatest sensitivity, while the use of antibodies adsorbed indirectly to assay tubes was superior in terms of practicability.