The principal male sex hormone.  An anabolic steroid secreted by the testes (and synthesized in small amounts in the ovaries and placenta), it is necessary for the development of the external genitals in the male fetus, and at puberty its increased levels are responsible for male secondary sex characteristics such as facial hair.

Further Reading and Resources:

Normal Adult XY Male Hormone Levels. Typical levels of Leutenizing Hormone(LH), Follicle Stimulating Hormone (FSH), Testosterone, and Estradiol-17 Beta.

Free & Bioavailable Testosterone calculator

Normal prepubertal XY male testosterone levels and Tanner Stages

Medscape DrugInfo.   Excellent drug database and information site.

Hypogonadism2 is the best e-mail list of its kind that I have found. Expect a LOT of well-informed expert mail. The list is very good for anyone who identifies as male and wishes to explore, understand, and use Tesosterone Replacement Therapy. To subscribe, please click here.

Problem with Androgel?.  Please read this report.

AACE clinical practice guidelines.  Easily the best site on the net for hypogonadism and testosterone use. 

A must read:  Male Testosterone Linked to High Social Dominance but Low Physical Aggression in Early Adolescence.

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