Evaluation and clinical application of the quantitative radioreceptor assay for serum hCG.

An evaluation of a radioreceptor assay (RRA) for the quantitation of human chorionic gonadotropin (hCG) in serum resulted in intra- and interassay variations of 2.6 and 5.5% (average), respectively. Recovery of hCG in a preparation of second IRP-hCG gave an accuracy of 93.2%. Standard curve data demonstrated that variation in reagent addition and incubation time allowed for flexibility in the use of the assay depending on the level of sensitivity desired. The most sensitive assay, which used an incubation of 2 hours, gave a usable range of 40--250 mIU/ml hCG on the standard curve. The applicability of the quantitative RRA in clinical cases is shown with 9 patients (total of 31 serum samples) in a comparison study with a radioimmunoassay (RIA) for the beta-subunit of hCG.

Application of the radioreceptor assay for human chorionic gonadotropin in pregnancy testing and management of trophoblastic disease.

A commercially prepared radioreceptor assay (RRA) for human chorionic gonadotropin (hCG) has been evaluated as a pregnancy test and in a quantitative assay to follow patients with hydatidiform mole. The RRA demonstrated almost 100% agreement in comparison with radioimmunoassay (RIA) and urinary hCG tests. In the quantitative assay, a limiting reliable concentration of 70 mIU/ml of hCG in serum could be obtained. Extremely good correlation was achieved between the RRA and RIA test for hCG in 2 patients with hydatidiform mole over a span of 3 months of followup after evacuation of the mole. The usefulness of the RRA as a replacement of RIA tests for hCG is discussed.

PIP: The use of a commercially prepared radioreceptor assay (RRA) for human chorionic gonadotropin (HCG) as a pregnancy test and in the follow-up of patients with hydatidiform mole is reported. In comparison with radioimmunoassay (RIA) and urinary HCG tests, the RRA gave results that were almost in 100% agreement. In 2 patients who were followed for 3 months after evacuation of a hydatidiform mole, the RRA and RIA showed an extremely good correlation. The limiting reliable concentration in the quantitative RRA assay was 70 mIU/ml of HCG in serum. The advantages and disadvantages of the RRA and RIA in a general hospital laboratory are discussed.

Synthesis of 14C-meglumine salicylate and its disposition in humans after oral administration.

The synthesis of 14C-meglumine salicylate was accomplished by heating 14C-meglumine with salicylic acid, in equimolar ratios, in 2-propanol. The average radiochemical yield was 97.5%. Ten healthy adult male volunteers were given 1.2 g of the compound orally. Five took 1.2 g of 1-deoxy-1-[14C]-methylamino-D-glucitol salicylate (containing about 47 micronCi), and five others took 1.2 g of 1-deoxy-1-methylamino-D-[U-14 micronCi), and five others took 1.2 g of 1-deoxy-1-methylamino-D-[U-14C]-glucitol salicylate (containing about 45 micronCi). Urine and feces were collected for 5 days, and blood was sampled for 24 hr. The peak urinary excretion of meglumine and/or its metabolites occurred between 4 and 8 hr after administration (about 7.2% of the administered dose). Meglumine was excreted primarily in the feces (72.4% over 5 days) and, to a smaller extent, in urine (21.3% over 5 days). No activity was detected in blood. The excretion rate and percentage excreted were the same for both groups of subjects, suggesting that meglumine was not metabolized by N-demethylation or conversion to carbon dioxide. The highest blood salicylate level, 44.4 +/- 1.9 microng/ml, was observed 1 hr after administration. Urinary levels of salicylic acid and its metabolites were observed to be at a maximum at 8 hr. Total salicylate recovery was 94.7 +/- 1.5% in 48 hr. Salicyluric acid was the major metabolite, accounting for 69.5 +/- 3.6% of the dose. Salicylic acid accounted for 6.8 +/- 1.2%.