How Hormones Affect the Penis: From Development to Aging

What is it about?

This paper is a chapter titled "Penis Endocrinology" from the 2026 edition of the Encyclopedia of Reproduction. It provides a comprehensive overview of how hormones—specifically androgens like testosterone and dihydrotestosterone (DHT)—control the development, function, and aging of the human penis throughout a man's life. Key topics covered include: The Role of Hormones: It explains the specific functions of hormones, such as DHT (crucial for forming the penis in the womb) and Testosterone (responsible for growth and secondary sexual characteristics during puberty). Life Stages: It tracks penile development from the prenatal stage (sex differentiation) through infancy, puberty, and adulthood. Aging and "Male Menopause": It discusses Late-Onset Hypogonadism (LOH), noting that testosterone levels drop by about 1% per year after age 30. It highlights how this hormonal decline can lead to erectile dysfunction, fibrosis (scarring), and even a physical reduction in penis size (shrinkage) as men age. Medical Conditions: The paper outlines various disorders caused by hormonal imbalances, such as micropenis (often due to Growth Hormone deficiency), delayed puberty, and Congenital Adrenal Hyperplasia (CAH). Treatments: It reviews potential solutions, including Testosterone Replacement Therapy (TRT) and specific surgical techniques (such as venous stripping and tunical patching) to treat structural issues like fibrosis

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Photo by vackground.com on Unsplash

Photo by vackground.com on Unsplash

Why is it important?

Here are the specific reasons why this work is significant: It Explains the "Why" Behind Penile Changes: It details how specific hormones like Testosterone and DHT have different jobs. For example, it clarifies that DHT is crucial for forming the penis in the womb , while Testosterone takes over for growth during puberty. It Validates the "Male Menopause" (LOH): It addresses the reality of Late-Onset Hypogonadism (LOH), explaining that testosterone naturally drops as men age (about 1% per year after age 30). It links this drop directly to symptoms like low libido, erectile dysfunction, and emotional changes. It Confirms Penile Shrinkage is Real and Explainable: The paper provides medical evidence that the penis can physically shrink with age due to fibrosis (scarring of the tissues) caused by low testosterone. It notes that a man's erect length could decrease by 0.5 to 1 inch between his 30s and 60s. It Connects Hormone Therapy to Physical Structure: It suggests that treating low testosterone (Testosterone Replacement Therapy) isn't just about libido; it may help prevent this fibrosis and structural damage. It even mentions surgical solutions (venous stripping and tunical patching) for severe cases. It Guides Diagnosis for Developmental Issues: It serves as a reference for diagnosing conditions affecting children and adolescents, such as micropenis (often linked to Growth Hormone deficiency) , delayed puberty , and genetic conditions like Congenital Adrenal Hyperplasia (CAH).

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