Androgen deficiency-related symptoms were found among men with low calculated free testosterone, even if they had normal total testosterone.
Researchers suggest that calculated free testosterone levels be assessed in men with suspected hypogonadal symptoms.
Vanderschueren, MD, PhD, clinical endocrinologist and head of clinic at the department of endocrinology at University Hospitals Leuven in Belgium, and colleagues evaluated data from the European Male Aging Study on 3,334 men aged 40 to 79 years to determine whether low calculated free testosterone or low total testosterone is associated more with androgen-related clinical endpoints.
Overall, 79.2% of participants had normal total/normal calculated free testosterone (referent group), 8.3% had normal total/low calculated free testosterone, 2.9% had low total/normal calculated free testosterone and 9.6% had low total/low calculated free testosterone.
The normal total/low calculated free testosterone group and low total/low calculated free testosterone group were older and in poorer health compared with the other groups.
Participants with normal total/low calculated testosterone had higher sex hormone-binding globulin levels, and the low total/normal calculated free and low total/low calculated free testosterone groups had lower levels compared with the referent group. The normal total/low calculated free testosterone and low total/low calculated free testosterone groups had higher luteinizing hormone levels compared with the other groups.
The lowest overall sexual function score, lowest gait speed and physical function score, and highest proportion of participants with erectile dysfunction, infrequent sexual thoughts and infrequent morning erections were found among the normal total/low calculated free testosterone group.
“In the presence of normal [total testosterone] levels, low [calculated free testosterone] levels are associated with androgen-related signs and symptoms in middle-aged and elderly men,” the researchers wrote. “We suggest including [free testosterone] measurements as part of the first-line assessment of hypogonadal symptoms in middle-aged/elderly and obese men.” – by Amber Cox
Vanderschueren reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.