Premium
Decline of plasma 5α‐dihydrotestosterone (DHT) levels upon testosterone administration to elderly men with subnormal plasma testosterone and high DHT levels
Author(s) -
Gooren L. J.,
Saad F.,
Haide A.,
Yassin A.
Publication year - 2008
Publication title -
andrologia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.633
H-Index - 59
eISSN - 1439-0272
pISSN - 0303-4569
DOI - 10.1111/j.1439-0272.2008.00857.x
Subject(s) - testosterone (patch) , dihydrotestosterone , endocrinology , medicine , androgen , chemistry , hormone
Summary The study was performed to measure the impact of testosterone (T) administration on circulating levels of 5α‐dihydrotestosterone (DHT). Group 1 (32 men; mean age 61 years; mean T 6.9 ± 1.9 nmol l −1 ) were treated for 15 months with long‐acting T undecanoate. Group 2 (23 men, mean age 60 years, mean T 7.6 ± 2.0 nmol l −1 ) were treated for 9 months with T gel. Plasma T and DHT were measured before and after 9 months T administration. In the men treated with T undecanoate plasma T and DHT were also measured after 12 and 15 months. Before T administration, plasma DHT ranged from 0.39 to 1.76 nmol l −1 (0.30–1.90 nmol l −1 ). Mean DHT declined upon T administration from 0.95 ± 0.50 to 0.55 ± 0.30 nmol l −1 ( P < 0.05). With an arbitrary cut‐off at 0.60 nmol l −1 , all 21 values of DHT > 0.60 nmol l −1 had fallen from 1.29 ± 0.50 to 0.70 ± 0.60 nmol l −1 ( P < 0.01). Below this cut‐off point 13 values rose and 21 fell upon T administration. Below this cut‐off point values on average declined from 0.39 ± 0.12 to 0.30 ± 0.14 nmol l −1 ( P < 0.05). The study revealed that in a cohort of elderly men with subnormal plasma T levels plasma DHT levels declined upon T administration when they were in the higher range of normal (>0.6 nmol l −1 ), with a profound shift of DHT/T ratios presumed to be an indicator of a reduced 5α‐reductase activity. Below plasma DHT levels of 0.6 nmol l −1 , responses of plasma DHT to T administration varied.