125: Testosterone – Dr. Serena McKenzie

Dr. McKenzie explains both sexes produce testosterone however it’s much more prevalent and important in men. Serena informs us that puberty is driven primarily by testosterone. She notes that testosterone production increases exponentially in men during puberty, peaks around age 30, and subsequently declines. From driving growth and facilitating sexual function to retaining bone density and cognitive function, Dr. McKenzie describes testosterone as a hormone with lifelong importance in men’s health.

Causes of Low Testosterone
Serena tells us the most direct cause of low testosterone, clinically diagnosed as testicular hypogonadism, occurs when the pituitary gland produces insufficient hormones to trigger adequate testosterone production. But she explains that many cases of low testosterone are caused by obesity, diabetes, insomnia, sleep apnoea, a sedentary lifestyle, smoking, excessive alcohol consumption, and other varieties of poor self-care. She also mentions that many clinicians understand lower testosterone levels as a natural result of aging, and not as a condition requiring treatment.

Symptoms of Low Testosterone
Dr. McKenzie admits that most of her patients present with sexual dysfunction. She often finds problems such as low libido, trouble gaining or sustaining an erection, fatigue, or depression. One symptom she describes that points directly to hypogonadism are a measurable decrease in testicular size. She mentions the loss of non-sexual erections as indicative of low testosterone. She points out that these symptoms can also be caused by vascular disease or pituitary dysfunction, but she reassures us that true cases of testosterone dysfunction can be diagnosed fairly easily by physicians.

How Low is Low?
To diagnose hypogonadism, Serena explains that labs look for reproducible testosterone levels below 300 or 350. The doctor explains that testosterone levels vary from day to day and hour to hour, which is why testing a man’