As males age, the concentration of testosterone (male sex hormone) in their blood gradually decreases.
In the European Male Aging Study (EMAS), which involved 3,220 men aged between 40 and 79, it was found that the total serum testosterone concentration decreases by 0.4% per year.
Another study indicated that testosterone levels decrease gradually after the age of 35, with a more noticeable decline after the age of 80.
Furthermore, The Baltimore Longitudinal Study of Aging (BLSA) discovered that using a threshold of 325 ng/dL for total serum testosterone, the prevalence of hypogonadism was 12% in men in their 50s, 20% in their 60s, 30% in their 70s, and 50% in their 80s.
Interestingly, although testosterone levels decline with age, the extent of decrease is not the same for every male.
One study revealed that when testosterone levels are arranged from highest to lowest within each age group, the lowest 2.5% of the population showed a decrease from 209 ng/dL in the 19-39 age range to 119 ng/dL in the 80-99 age range.
The median 50% group decreased from 507 to 446 ng/dL, while the highest 97.5% group remained almost unchanged at 902 ng/dL.
This suggests that populations with initially lower testosterone levels may experience a greater decrease in the future.
So, does this age-related fall in testosterone have an impact on health?
Current research suggests that the decline in testosterone associated with aging is related to the following conditions:
l Decline in libido and sexual activity
l Significantly decreased muscle mass and strength
l Depressed mood
l Significantly decreased bone mineral density (BMD)
l Significantly lower hemoglobin levels (anemia)
l Insulin resistance and the metabolic syndrome
l Poorer general health
In summary, the decline in serum testosterone might be a cause of the various effects of aging on health.
So, why do male hormones decrease with age?
1. Leydig cells, which produce testosterone, decrease over the years.
Cadaver studies have found that the volume of interstitial cells of the testes, known as Leydig cells, significantly decreases with age.
According to research, a pair of testes in young men (around 20 years old) contains approximately 700 million Leydig cells, and there is a loss of about 80 million cells every decade.
2. Serum sex hormone-binding globulin (SHBG) concentration increases with age.
Testosterone exists in various forms in the serum, each with different biological activity.
The "free" or "unbound" testosterone (1-2% of total) is fully biologically available.
Other forms of testosterone are bound to proteins.
"Albumin-bound testosterone" (40% of total) is also biologically available, but "SHBG-bound testosterone" (60% of total) is an inactive form.
Therefore, when SHBG increases with age, it indicates an increase in the "inactive form of testosterone," resulting in a decrease in biologically available testosterone.
Research has shown that the concentration of "biologically available testosterone" in men decreases by 50% between the ages of 25 and 75.
3. Effects of obesity and comorbid conditions.
Studies have found that total testosterone levels are lower in obese men compared to men of the same age with normal weight.
Men with one or more comorbid conditions also have lower total and free testosterone levels compared to age-matched men without comorbidities.
In simple terms, obesity or other comorbid conditions can contribute to lower total and free testosterone levels.
Brief Summary:
With the trend of population aging, living a healthy and vibrant life has become a commonly concerned issue.
The issue of aging caused by low male hormones is quite common.
Under the careful evaluation of healthcare professionals, supplementing male hormones is an effective, safe, and quality-of-life-enhancing treatment method.
Referenes:
Smith and Tanagho's General Urology
Hypothalamic-pituitary-testicular axis disruptions in older men are differentially linked to age and modifiable risk factors: the European Male Aging Study
https://pubmed.ncbi.nlm.nih.gov/18270261/
Age-specific population centiles for androgen status in men
https://pubmed.ncbi.nlm.nih.gov/26385186/
Harmonized Reference Ranges for Circulating Testosterone Levels in Men of Four Cohort Studies in the United States and Europe
https://pubmed.ncbi.nlm.nih.gov/28324103/
The male menopause: does it exist?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1070997/
Testosterone for the aging male; current evidence and recommended practice
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2544367/
Secondary hypogonadism in older men: its relation to impotence
https://pubmed.ncbi.nlm.nih.gov/2205629/
