Hormones 2016

Dihydrotestosterone - DHT
elevations may be observed in 21-hydroxylase deficiency (the most
common form of CAH) and 11 beta-hydroxylase deficiency. By contrast,
steroidogenic acute regulatory protein or 17 alpha-hydroxylase deficiencies
are characterized by low DHEA-S levels.
An initial panel in adults might also include total and bioavailable testosterone
(TTBS / Testosterone, Total and Bioavailable, Serum) measurements.
Depending on results, this may be supplemented with measurements of
sex hormone-binding globulin (SHBG / Sex Hormone-Binding Globulin
[SHBG], Serum) and, occasionally other androgenic steroids (eg, 17-
hydroxyprogesterone) (Medical, 2014).
Dihydrotestosterone - DHT
Dihydrotestosterone measurement is used to diagnose 5α-reductase deficiency
and for the evaluation of androgen utilization. Dihydrotestosterone
is produced by the reduction of testosterone by 5α-reductase in the target
organs. Circulating dihydrotestosterone is tightly bound to sex hormonebinding
globulin. The free fraction represents the dihydrotestosterone
available to act on tissues (labcorp, 2016a).
Low levels of DHT indicate general androgen deficiency or poor 5αreductase
activity. Low levels of testosterone, DHEA and androstenedione
can be causative factors of reduced DHT levels. This may result in
diminished sex drive and poor muscle tone (gdx, 2008).
This is a more potent form of testosterone that is metabolized by the body
from other androgens. In men most is made from testosterone, while in
women the main source is androstenedione (which is first converted INTO
testosterone). Current research indicates that DHT is responsible for malepattern
balding and excessive, unwanted hair in both sexes. In males it is
also responsible for non-cancerous prostate swelling (BPH).
The principal prostatic androgen is dihydrotestosterone (DHT). Levels
of DHT remain normal with aging, despite a decrease in the plasma
testosterone, and are not elevated in benign prostatic hyperplasia (BPH) (S,
Levine, and Chow, 1979).
DHT is generated by reduction of testosterone by 5α-reductase. Two
isoenzymes of 5α-reductase have been discovered. Type 1 is present in most
tissues in the body where 5α-reductase is expressed, and is the dominant
form in sebaceous glands. Type 2 is the dominant isoenzyme in genital
tissues, including the prostate.
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Version 2016.3576– – Document LATEXed – 1st May 2016
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