Opioid Treatment Lowers Men's Testosterone Levels

Opioid treatment suppressed testosterone levels in men, yet the therapy left women’s testosterone levels unaltered, McMaster University researchers found.

In Scientific Reports, researchers enrolled 231 patients treated for opioid dependence at methadone clinics in Ontario, Canada. For a control, 738 non-opioid users were recruited from primary care facilities.

From there, information involving participants’ demographic details, substance use, and psychiatric history was taken in addition to blood and urine samples.

To maintain the study’s integrity, subjects treated with anything other than methadone for opioid substitution therapy, who did not speak English, and who declined to provide samples were excluded from observation. Additionally, women taking hormonal medication including birth control, hormone replacement therapy, and thyroid medications were also eliminated.

The investigators reported lowered testosterone levels in men who underwent methadone treatment (mean = 100.10 ng/dL, SD 72.21, or 3.47 nmol/L, SD 2.51) compared to healthy controls (mean = 414.74 ng/dL, SD 141.81, or 14.39 nmol/L, SD 4.92) (estimated β = −1.661; 95% confidence interval [CI] −1.793, −1.529; p < 0.0001).

However, there was no significant difference between testosterone levels in women on methadone (mean = 36.61 ng/dL, SD 23.19, or 1.27 nmol/L, SD 0.81; and mean = 25.93 ng/dL, SD 15.20, or 0.90 nmol/L, SD 0.52, respectively) and healthy patients (estimated β = 0.063; 95% CI −0.098, 0.224; p = 0.441).

Furthermore, the investigators delved into testosterone variation during women’s menstrual cycle. Based on a linear regression model, they found no significant testosterone fluctuation during menopause and phases of menstruation (estimated β = −0.992; 95% CI −21.263, 19.279; p = 0.923).

“Measurement of serum total testosterone level in future investigations does not need to account for menstrual cycle phase, as testosterone levels at any given time are generally representative of the average testosterone level in women,” the researchers noted.

To effectively treat and prevent testosterone suppression, the investigators suggested men’s levels be checked before and during opioid therapy.

In a statement, principal investigator Dr. Zena Samaan of McMaster’s Michael G. DeGroote School of Medicine recommended doctors to prescribe opioid doses that effectively treated patients, but didn’t negatively affect their testosterone levels.

“We expect that treating testosterone deficiency will improve outcomes of methadone treatment for patients, including treatment response and retention,” Samaan said.