Plasma Dihydrotestosterone in Normal Adult Males and Its Relation to Testosterone

Abstract

A radioimmunoassay for dihydrotestosterone (DHT) in plasma was developed using an antiserum raised against testosterone-3-oxime-bovine\x=req-\ serum-albumin. After extraction of 1 ml male plasma with diethylether, DHT was separated from testosterone (T) by thin-layer chromatography. A dextran-charcoal-suspension was used for the separation of bound and free ligand. The inter-assay variability was 10.4 % (C. V.) and the detection limit 1.77 ng/100 ml. The accuracy of the method as determined by mass recoveries and the specificity were shown to be satisfactory. Normal values were obtained in 45 young to middle-aged (22\p=n-\61years) and 37 old (68\p=n-\93years) men. The median and the 95 percentiles were 20.5\p=n-\51.9\p=n-\76.3 (ng/100 ml) and 19.5\p=n-\50.9\p=n-\101.5 (ng/100 ml) respectively. While DHT did not change in old age T fell by 20.6%. DHT and T showed a significant correlation: rS = 0.426, P < 0.01 (young men), rS = 0.752, P < 0.001 (old men). After 3 daily im injections of 5000 IU human chorionic gonadotrophin (HCG), DHT increased 1.50 times (range: 1.15\p=n-\2.09,n = 12), T 1.86 times (range: 1.20\p=n-\2.91,n = 12). After 4 daily administrations of 40 mg fluoxymesterone DHT fell to 29.6% of the control level (range: 16.0\p=n-\48.2%, n = 12). Blood samples were obtained from a 24 year old man every 15 min for 24 h. A close parallelism was observed between the concentrations of DHT and T in the plasma.In recent years a good deal of evidence has been accumulated that dihydro¬ testosterone (DHT), the main metabolite of testosterone (T) in male target organs, may be the active hormone with regard to many but not all androgen

Prepubertal Diagnosis of Steroid 5α-Reductase Deficiency*

“…Both in normal adult males (20,21), and probably also in normal male children as shown here, a DHT rise paralleling T after hCG stimulation is expected. This would then lead to a constant T:DHT ratio of approximately 10:1 as it exists in the baseline state in normal adult man (20,21).…”

Age-dependent change of serum 5.ALPHA.-dihydrotestosterone and its relation to testosterone in man.

“…This is in agreement with the observation of Mauer et al (1973), Pirke et al (1975) and Hosaka (1976). These results suggest that DHT is converted from T at a rapid rate depending on the serum T concentration.…”

“…A specific and reliable radioimmunoassay for DHT and T has been developed using antiserum against T-3-oxime-BSA. Normal values obtained with this method are in good agreement with the data in the literature (Ito and Horton, 1971;Gupta et al, 1972;Pirke et al, 1975;Lewis et al, 1976). We reported that serum T levels remained within the same range from adolescence to the age of the 7th decade, then from the 8th decade its levels rapidly decreased.…”

Simultaneous Measurement of Serum Testosterone and Dihydrotestosterone by Liquid Chromatography–Tandem Mass Spectrometry

“…The fact that the serum DHT concentration is only one tenth that of T makes serum DHT quantification more complex (3 ). RIA methods require extraction and chromatography (17)(18)(19) or oxidation of T by potassium permanganate (20,21 ). Recently, methods with improved limits of quantification that use liquid-or solid-phase extraction, chromatography, derivatization, and GC-MS or LC-MS/MS have been applied to the measurement of T, DHT, and other androgens in rat tissues (22,23 ), human adrenal cell culture medium (24 ), and human sera and testicular fluid (25,26 ).…”