Men suffering from an overactive thyroid
gland are at an increased risk for severe erectile dysfunction
according to new research presented at the joint International
Congress of Endocrinology and European Congress of Endocrinology in
Florence, Italy.
A multicentre European research group
led by Professor Frederick Wu (University of Manchester) and
Professor Mario Maggi (University of Florence) demonstrated for the
first time that hyperthyroidism can negatively affect a man’s
erectile function.
As many as six out of ten men suffering from overt hyperthyroidism
could struggle to maintain an erection.
Hyperthyroidism is a common condition
where the thyroid gland becomes overactive and produces too much
thyroid hormone. Thyroxine, the main hormone, plays a vital role in
digestion, heart and muscle function, brain development and
maintenance of bones. Symptoms of hyperthyroidism include tiredness,
mood disturbances such as irritability and depression, increased
sweating and weight loss. If left untreated it can cause serious
health problems including heart failure and stroke.
The current research investigated the relationship between thyroid
hormones and erectile function in two large samples totalling 6573
men.
The first group (3370 community dwelling men aged between 40 and 79
years) came from the European Male Aging Study (EMAS), a large
multicentre survey spanning eight European countries.
The second group consisted of 3203 heterosexual male patients
(average age 52) seeking treatment for sexual dysfunction at the
University of Florence’s Andrology and Sexual Medicine Outpatient
Clinic (UNIFI study).
The researchers tested for thyroid
stimulating hormone (TSH) – responsible for controlling the
production of thyroid hormones – and free thyroxine (FT4), the
active form of the hormone thyroxine circulating in the blood. They
found clear cases of overt hyperthyroidism (reduced TSH and elevated
FT4) in nine individuals (0.3%) from the EMAS study and seven
patients (0.2%) from the UNIFI study, numbers consistent with the
disease’s prevalence in the general population.
In both groups there is a clear link
between hyperthyroidism and an increased risk of severe erectile
dysfunction. The results show that the lower the level of TSH
detected in patients the higher their risk of suffering from
erectile dysfunction (ED). Men with hyperthyroidism were 14 times
more likely than their peers to suffer from ED in the EMAS study,
and 16 times more likely in the UNIFI study.
In contrast, men suffering from erectile problems were not found to
be at higher risk for developing hyperthyroidism.
Erectile dysfunction (ED), also known as impotence, is the inability
to achieve and maintain an erection that is sufficient for sexual
intercourse. ED is a very common condition, affecting around one in
ten men, with that number rising significantly as men age.
Researcher Dr Giovanni Corona, from the
University of Florence, said:
“While anecdotal data indicates that erectile dysfunction is
frequent in men with hyperthyroidism, this theory has only been
superficially investigated. We demonstrated for the first time in
two large samples that there is a strong correlation.
“Further studies need to look at the direct effect of thyroid
hormones on penile structures as well as the effect of thyroid
therapy on sexual function.
“Hyperthyroidism is one of the most important causes of medical
consultation in the world. To check sexual function in these
patients could dramatically improve their quality of life.”
A variety of drugs including
psychotropics, antihypertensives, diuretics, and others, may cause
ED. In the study approximately one third of patients and controls
were on medication. Patients and controls were on similar classes of
drugs, so drug effects are unlikely to account for the differences
in the two groups.
The mechanism by which thyroid
dysfunction can cause ED has not been investigated in this study
because it was outside the scope of the investigation. However, one
can hypothesize that ED may result from a complex interplay between
altered erectile nerve function, cognitive decline, illness-related
stress, and decreased interpersonal interaction. Abnormalities of
endocrine function may also have implications on erectile function.
For hypothyroid patients such abnormalities have been described.
Specifically, it is well established that hypothyroidism may be
associated with a decrease in serum testosterone, DHEA, and DHEA
sulfate. In our study, correction of thyroid dysfunction led to
restoration of erectile function in most patients. Thus, screening
for thyroid dysfunction in men presenting with ED is recommended.
Furthermore, specific treatment of ED with selective
phosphodiesterase-5 inhibitor should be postponed for at least 6
months after restoration of euthyroidism.
This study demonstrates, for the first
time in a controlled manner, that ED is extremely common in males
with thyroid disturbances and treatment of the primary disease can
restore normal erectile function. Moreover, a significant positive
correlation was found between SHIM scores and FT4, and a negative
correlation between SHIM scores and TSH. The study also showed that
after 8–9 months of euthyroidism, the prevalence of ED declined
significantly to levels comparable with those of controls. Screening
for thyroid dysfunction in men presenting with ED is recommended,
whereas specific treatment of ED should be postponed in patients
with thyroid dysfunction until euthyroidism has been reached for at
least 6 months because the latter might principally be responsible
for ED.
For more information
Erectile Dysfunction in Patients with Hyper- and Hypothyroidism: How
Common and Should We Treat?
http://jcem.endojournals.org/content/93/5/1815.full
http://www.ese-hormones.org/
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