Steroid hormones, isotope studies

The hydrolysis of steroid hydrogen sulphates, important to biochemists in view of the excretion of many steroid hormone metabolites as water soluble salts of hydrogen sulphates, has been studied in some detail [20,21]. It had been known for some years that ether extraction of the steroid hydrogen sulphate from acidified solutions is accompanied by hydrolysis of the sulphate in the ether phase, with liberation of the steroid alcohol. This hydrolysis was shown to follow first-order kinetics, but to be dependent in a remarkable way on the solvent. Ethers are the most effective solvents, followed by others of low polarity including benzene, esters and ketones, while water and alcohols have a strong retarding effect on hydrolysis. Neither acids nor bases produce significant catalysis, and the presence of did not result in incorporation of isotopic... 

Steroid hormones by the application of isotope tracer techniques 3I8-321]. Lieberman and co-workers undertook urinary metabolic studies [304,325] by administration of isotopically labeled steroids followed by the determination of specific activities of urinary metabolites derived only from the administered substance. Mathematical analyses were performed by compartmentalization of the metabolism [385]. One- or two-compartment systems are most frequently used [304,306,384,386,387]. A compartment is defined as a particular species (e.g., dehydroepiandro-sterone sulfate) in a particular space (e.g., peripheral organ). It is assumed that a species entering a compartment mixes immediately with the whole compartment. Two factors were responsible for the institution of com-partmental analysis ... 

In addition to estimation on the basis of urinary metabolic studies, blood production rates of steroids can be estimated, after administration of isotopically labeled steroids, from the specific activity of the unchanged steroids in the blood. This method was extensively used by Tait and coworkers [322,324]. In 1966 a critical survey of steroid hormone metabolism was given by Baulieu [385]. 

Although one would like to see the precision of these methods improved, it should be realized that most diagnostic problems in this field involve elevations in steroid levels in plasma or urine of the order of 2- to 10-fold and often of several hundredfold. By many criteria these levels of precision vary from not quite, to reasonably, adequate (W3). Despite the lack of quality control the satisfactory precision achieved by most modern methods for individual steroids is indicated by more recent studies in which they have been used for measurements of steroids providing rather sharp discrimination of normals from diseased patients. There is also reasonable concordance between normal values achieved by different workers for many steroid sex hormones and their metabolites. Also, in these studies the better GLC and double-isotope LLC methods are in general agreement (E2, T5). 

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