Determination Of Testosterone In Plasma Research Articles

Evaluation of GLC technique for the estimation of androgens

The methods in use in the authors laboratory for the determination of plasma testosterone, androstenedione and dihydrotestosterone are described and possible pitfalls are discussed. The gas-chromatographic methods are compared to methods based on competitive protein binding and the pros and cons of each are discussed. It appears that in expert hands GLC methods for plasma androgens are not inferior to methods based on CPB, the only advantage of the latter being their greater practicability, which is however largely neutralized by the lack of specificity of CPB methods, requiring extensive preparatory purification of material used.

Preoperative detection of hidden testes.

A method for detecting occult Leydig cell tissue of the testis utilizes the determination of plasma testosterone or testosterone production before and after administration of chorionic gonadotropin. The method was applied successfully to the detection of testes in a boy with bilateral cryptorchidism, who had been unsuccessfully explored for testes, and in a true hermaphrodite. It is recommended that testosterone determinations after chorionic gonadotropin be applied to detect testes in prepubertal children with bilateral cryptorchidism, testicular feminization, and ambiguous genitalia.

Testosterone assays by competitive protein binding.

ABSTRACT A review of competitive protein binding methods for the determination of testosterone in plasma is given. The different steps discussed are: Choice of the binding protein, dilution of the protein solution, separation of the free from the bound fraction, purification of the extract and factors determining the blank. The method used in the author's laboratory is critically discussed. The recovery is 98% ± 4% at 1 ng. The coefficient of variation is 3% at 660 ng/100 ml, 13% at 35 ng/100 ml, and 40% at 20 ng/100 ml. The sensitivity is about 10 ng/100 ml.

A clinically useful method for plasma testosterone determination

A simple method has been developed for clinically measuring plasma testosterone. Its sensitivity allows one to measure normal female levels of plasma, and the results are comparable to those obtained by double isotope derivative methods. This procedure requires paper chromatography of a methylene chloride extract of plasma and final determination by the competitive protein-binding technique, using salt precipitation of the bound fraction. By this method, the normal range for plasma testosterone was 26 to 108 mμg/100 ml in females and 273 to 1211 mμg/100 ml in males.

Determination of plasma testosterone as the heptafluorobutyrate using gas liquid chromatography with electron capture detection

A sensitive method for the determination of free testosterone in human peripheral plasma using heptafluorobutyrates with an electron capture detector coupled to a gas chromatograph has been described. Sensitivity of the method is such that it should be possible to measure as little as 0.005μg/100 ml plasma. The method involves extraction, purification of the extract by TLC, esterification with heptafluorobutyric anhydride, TLC of the ester and finally GLC of 1% XE-60.

Determination of plasma testosterone by the use of competitive protein binding.

A method is described for the determination of plasma testosterone using competitive protein binding. Two ml plasma volumes were used for each analysis in women and 0.2 ml in the case of men. Precision of the method, evaluated by determining the coefficient of variation of analyses of pools of plasma, was 3.8% for plasma from men and 5.3% for plasma from women. Accuracy was measured by analysis of 2 ml volumes of plasma to which known amounts of testosterone had been added. There was a linear relationship throughout the range examined from 0 to 750 μg/100 ml. Specificity of the present method was compared with alternative procedures which employed chromatography in different systems and derivative formation. There were no significant differences in the results when these alternative procedures were used. Ten steroids were identified which bind to testosterone binding protein with an affinity 5% or more of that of testosterone. The method is easier to perform than those using double isotope dilution to measure small amounts of testosterone. The mean plasma testosterone concentration in 18 normal women was 40 ± 14 (sd) m/g/100 ml. In 16 normal men the mean was 680±180 (sd) mμg/100 ml. Two of 3 children with feminizing testes had plasma testosterone concentrations below the normal adult female range, while a third child with the disease had a level within the normal adult female range. All 3 children with feminizing testes developed plasma testosterone concentrations above the normal adult female range after administration of human chorionic gonadotrophin.

Ultramicro determination of plasma testosterone by electron-capture detection of testosterone diheptafluorobutyrate.

1. A new highly sensitive and accurate ultramicro method for the estimation of testosterone in human peripheral plasma is described. The method uses paper-and thin-layer-chromatographic separation of plasma testosterone, which is determined as testosterone diheptafluorobutyrate by electron-capture detection after gas-liquid chromatography. 2. The average difference between duplicates is +/-2% (range 1-5%) with as little as 2.5ml. of human male peripheral plasma. With 10ml. of plasma the method is sensitive enough for the accurate determination of testosterone in human female plasma. The high order of accuracy is achieved by the use of a radioactive label and an internal standard for gas chromatography, and by obtaining several gas chromatograms from the same plasma sample. 3. As little as 40mumug. of peripheral plasma testosterone can be detected. The method is 20 times as sensitive as electron-capture techniques with the monochloroacetate derivative. 4. The method is simpler and quicker than double-isotope-derivative methods, and slightly more sensitive. The advantages of the method, which is specific for testosterone, are its high sensitivity and accuracy, which are achieved with relative convenience.

The evaluation of a gas-liquid chromatographic method for the determination of plasma testosterone using nickel-63 electron capture detection

A method is described for the determination of testosterone in human peripheral venous plasma. The procedure involves addition of a labelled internal standard, mild saponification with sodium hydroxide, extraction with diethyl ether and preliminary purification on thin-layer chromatography. After formation of the heptafluorobutyrate derivative, the extract is rechromatographed on silica gel, followed by gas-liquid chromatography using a solid injection technique, Nickel-63 electron capture detection and electronic digital integration. The percentage error associated with each part of the procedure has been estimated and the total theoretical random error determined for each assay. In addition, the practical errors have been determined by replicate analyses. The method has been applied to the determination of testosterone in plasma from 41 healthy males (mean 528 ± 261 ng/100 ml plasma) and 20 healthy females (mean 40 ± 14 ng/100 ml plasma).

Studies in steroid metabolism XX. “The determination of plasma testosterone using thin-layer and gas-liquid chromatography.”

A method has been devised for the relatively rapid and sensitive determination of testosterone in human plasma. The procedure incorporates a thin-layer chromatogram to separate most of the 17-ketosteroids from testosterone followed by GLC on silicone elastomer. An average recovery of 39% of added 3H-testosterone was obtained, Values for young males of 0.30–1.27 μg 100 ml of plasma were found.

Determination of plasma testosterone.

ABSTRACT A chemical method for the determination of testosterone in plasma is described. In this method testosterone is separated by paper chromatography. After further purification by chromatography on aluminum oxide a micro modification of the reaction of Koenig et al. (1941) is applied for quantitation. By the present procedure as little as 0.2 μg testosterone can be determined with adequate accuracy in appropriate plasma volumes.