5α-Reductase Deficiency

Definition of 5α-Reductase Deficiency

5α-reductase deficiency hinders testosterone conversion into dihydrotestosterone and causes male pseudohermaphroditism.

Signs and Symptoms of 5α-Reductase Deficiency

5α-reductase deficiency affects only males
Signs at birth are various, from proximal hypospadia to ambiguous genitalia: small phallus, blind ending vagina and labioscrotal fusion.
The testes are located in the labia or cryptorchidism is present.
The onset of puberty results in a masculinization (voice, body habitus, genital growth, descensus of the testes) through the conversion of the rising testosterone by the 5α-reductase activity in the skin.
Gynecomastia is not typical for 5α-reductase deficiency.

Diagnostic Work-Up

Elevated testosterone and low dihydrotestosterone.
Low or absent 5α-reductase activity of cultured genital skin fibroblasts.

Treatment of 5α-Reductase Deficiency

With early diagnosis, a male gender assignment is reasonable, since with the beginning of puberty, a strong male gender identity will develop. Hypospadia should be corrected early. Substitution of dihydrotestosterone or higher doses of testosterone stimulate the genital growth in puberty. Fertility is possible with the help of intrauterine insemination.

In missed diagnosis and female gender assignment after birth, orchiectomy, female hormone replacement and surgical corrections are possible, but should be deferred until the end of puberty (Cohen-Kettenis, 2005).

Testicle diseases

Index

Vanishing testis

Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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References

Cohen-Kettenis, P. T.: Gender change in 46,XY persons with 5alpha-reductase-2 deficiency and 17beta-hydroxysteroid dehydrogenase-3 deficiency.
Arch Sex Behav, 2005, 34, 399-410

Deutsche Version: 5α-Reduktase Mangel

Last update

Dr. med. Dirk Manski
man...@urologielehrbuch.de