A male's total testosterone level may be linked to more than just sexual health and muscle mass preservation, a new study finds. Low amounts of the hormone could also be associated with chronic disease, even among men 40 years of age and younger.
"If we look at data for men from a population level, it has become
evident over time that chronic disease is on the rise in older males,"
says Mark Peterson, Ph.D., M.S., FACSM, lead author of the study and assistant professor of physical medicine and rehabilitation
at Michigan Medicine. "But we're also finding that a consequence of
being obese and physically inactive is that men are seeing declines in
testosterone even at younger ages."
Published in Scientific Reports, Peterson and colleagues studied this relationship among testosterone, age and chronic disease.
"Previous research in the field has shown that total testosterone
deficiency in men increases with age, and studies have shown that
testosterone deficiency is also associated with obesity-related chronic
diseases," Peterson says. "But it hasn't been previously understood what
the optimal levels of total testosterone should be in men at varying
ages, and to what effect those varying levels of the hormone have on
disease risk across the life span."
The study's basis came from previous work from other researchers
that appeared to define normal ranges of testosterone but didn't use
population-representative cohorts, he says.
"Previous studies used clinical cohorts that were not reflective of
the current male population in the United States," Peterson says. "The
cohorts they used enforced strict guidelines for patients that were
accepted into the cohort. Therefore, those patients tended to be much
Peterson and colleagues, then, leveraged a population sample that
was much more representative of males in the United States today.
Multimorbidity across age groups
Using data from the National Health and Nutrition Examination Survey, the research team examined the extent to which hypogonadism is prevalent among men of all ages.
Of the 2,399 men in the survey who were at least 20 years old, 2,161
had complete information on demographics (e.g., age, ethnicity and
household income), chronic disease diagnoses, blood samples obtained for
total testosterone, grip strength and lab results for cardiometabolic
disease risk factors.
Peterson and team then examined prevalence of nine chronic
conditions, including type 2 diabetes, arthritis, cardiovascular
disease, stroke, pulmonary disease, high triglycerides,
hypercholesterolemia, hypertension and clinical depression.
The researchers studied the prevalence of multimorbidity, or when
two or more of the chronic conditions were present, among three age
groups (young, middle-aged and older men) with and without testosterone
deficiency. They found that low total testosterone was associated with
multimorbidity in all age groups -- but it was more prevalent among
young and older men with testosterone deficiency.
"We also found a large dose-response relationship between the
age-specific low total testosterone and moderate total testosterone
levels and multimorbidity, even after adjusting for obesity and muscle
strength capacity," Peterson says. "Which means that men should be
concerned about declining total testosterone, even if it has not reached
a level to warrant a clinical diagnosis (<300 dl="" ng="" nmol="" p="">
Co-author Aleksandr Belakovskiy, M.D.,
a resident in family medicine at Michigan Medicine, who helped to
design and carry out the study, notes that the results show the need for
further testing and research.
"This study showed a robust association between testosterone and
multiple medical morbidities that could influence the way we think about
testosterone in general practice," Belakovskiy says. "While these
findings cannot prove causation, it does spark the need for better
clinical awareness and more research."
The team hopes the study and its results can serve as a public service announcement for men.
"A lot of men may not be aware of the risk factors for testosterone
deficiency because of their current lifestyle," Peterson says. "And more
importantly, that declining levels could be contributing to a silent
decline in overall health and increased risk for chronic disease."