In reviewing several evidence-based studies from the Journal of Sexual Medicine over the past few years, I’ve collected several bits of interesting information that fall into the following three categories:
- The interrelationship between testosterone levels and cardiovascular and metabolic aberrations in men
- Rethinking the role of testosterone in sexual health in prostate survivors
- Statistics about “average penile size”. Get out those tape measures, guys!
One: Low testosterone, erectile dysfunction, and cardiovascular ills
The interrelationships between men’s metabolic dysfunctions (cholesterol, blood sugar, heart and vascular problems, etc.), testosterone levels, and erectile function are well established. Low testosterone (T) is unhealthy and is linked to metabolic syndrome, cardiovascular disease, and death. Metabolic syndrome (MeS) is a constellation of 3 or more out of five different symptoms: hypertension, abnormal glucose tolerance (especially adult-onset diabetes), obesity (defined as a waist > 40 inches in men), abnormal lipids (most notably low HDL-cholesterol (HDL-C) and elevated triglycerides, and a condition called “Insulin Resistance” where the body produces too much insulin in response to carbohydrates — especially simple carbs — resulting in wildly fluctuating blood glucose levels. Having MeS confers a 5 to 10-fold increased overall risk of cardiovascular death. The more symptom a patient has, and the more severe their symptoms are, the higher the risk. MeS is one of the most important public health issues threatening the health of men and women all over the world.
MeS is — by itself – considered a risk factor for erectile dysfunction (ED). The clinical management of MeS can be done through therapeutic interventions including lifestyle modifications, T replacement alone or in combination with a PDE-5 inhibitor (Viagra™, Cialis™, etc.), and other pharmacologic treatments. For those who are interested, a complete review of how MeS affects erectile function can be found in the review by Kaya, et al, referenced below.(1)
In a 2015 article in the Journal of Sexual Medicine(2), Beseroglu and colleagues report a review of 8 articles with > 12,000 participants. They found a 2.6-fold increase in ED inpatients with MeS. All individual components of MeS except HDL-C were also found to correlate with increased prevalence of ED. Of these, abnormal blood sugars and especially diabetes was noted to cause the highest rate of ED.
Turning things around, ED has been noted in several studies as a marker for cardiovascular disease and type 2 diabetes. Elevated blood glucose, central obesity and low T levels are more prominent in men consulting for ED than in the general population. Low T is associated with impaired glucose tolerance. As the penile artery is a narrow vessel, its further narrowing via arterial plaques may significantly affect the ability of a sufficient volume of blood to enter the penis for a “working” erection. In particular, younger men with ED (ages 40s and 50s) are very significantly at elevated risk for heart disease and should be referred to a cardiologist for evaluation.
In another study from Germany and the U.S. titled, “Weight loss and reduction of waist size in 237 hypogonadal men with obesity grades I-III under long-term treatment with testosterone”, presented at the 16th World Meeting on Sexual Medicine in Sao Paulo, Brazil in 2015, T therapy seemed, along with lifestyle changes, to be an effective approach to achieving sustained weight loss in obese hypogonadal men, thereby potentially reducing cardiometabolic risk.
The obvious take-home here is that if you’re fat, have impaired glucose tolerance, hypertension, and perhaps poor lipids, you are much more likely to have low T, ED, and a significantly lower life expectancy. Time for a paradigm shift.
Two: Testosterone replacement in men with prostate cancer
There has been controversy recently regarding the safety of T supplementation or replacement in men with prostate cancer. From 2001 to 2013 the number of patients diagnosed with T deficiency syndrome has more than tripled, and it is clear that a sizable percentage of men with T deficiency experience significant improvements in quality of life following T supplementation. However, results from several recent meta-analyses of clinical trials suggest that although low T correlates strongly with other co-morbid conditions (as noted above in this blogpost), the effect of supplementation of T alone on these conditions (as opposed to lifestyle plus T) is relatively limited and, as such, T may be better understood as an indicator of overall health rather than a causative factor.
T supplementation is well recognized to result in the progression of metastatic prostate cancer. This data has been extrapolated, with currently available guidelines recommending against T therapy in men with existing prostate cancer. While T supplementation may be administered in men with excised cancer, among men undergoing resection of localized prostate cancer micrometastatic disease has been identified using sensitive assays (PET scans, etc.)
With this in mind, several studies have evaluated the effect of T supplementation in men with prostate cancer. These studies carefully followed men with early stage disease with surgical excision, and men who elected to forgo surgery, managing them instead with “active surveillance” without surgery. These 4-5 studies, which unfortunately include only a total of 200 men followed for 2-5 years with PSAs generally < 5, tend to show that in selected men with early-stage prostate disease of complete surgical excision, supplemental T may be given provided that surveillance is rigid. This path, however, is not the present “standard of care,” and should be embarked upon with caution.(4)
Three: Average penile size.
In a study replicating previous research(3) Hablous, et al establish the following reassuring measurements: The mean suprapubic (top of penis , skin measurement from base of penile shaft) skin to tip erect penile length in men is slightly under 5 inches. Mean symphysis pubis (pressing down to the bone at the base of the upper surface of the erect penis) to tip length is 5.65 inches. Mean shaft diameter (measuring all the way around) is 4.5 inches. All of these measurements have a “standard deviation” (plus/minus) of 2/3’s to ¾’s inches. How do you measure up?
- “The relationship between metabolic syndrome, its components, and erectile dysfunction: A systematic review and a meta-analysis of observational studies.” Kaya et al. Journal of Sexual Medicine 2015;12:856-875.
- “Erectile dysfunction as a marker for cardiovascular disease: Diagnosis and intervention” Pastuszuk et al. Journal of Sexual Medicine 2015;12:975-984.
- “Erect penile dimensions in a cohort of 778 Middle Eastern men: Establishment of a nomogram.” Hablous et al. Journal of Sexual Medicine 2015;:1402-1406.
- “Testosterone deficiency, supplementation, and prostate cancer: Maintaining a balanced perspective”, Journal of Sexual Medicine 2013;10:209-218; “Testosterone replacement therapy in men undergoing active surveillance for prostate cancer” presented by Berookhen et al at the 16th World Meeting of Sexual Medicine, 2015, Sao Paulo, Brazil.