A 17-year population study in Minnesota uncovered suggestions that the rate of decline in testosterone levels may play a role in the rate at which BPH increases and urinary flow decreases, but the associations are far from clear.
"It is well established that BPH is hormone dependent, but associations between sex steroid hormones and outcomes are modest, at best," said Jennifer St. Sauver, PhD, the study's first author, who is associate professor of epidemiology at Mayo Clinic, Rochester, MN. "Most studies show a single point in time, so we looked at associations over time in an attempt to determine which men are at greatest risk of rapid declines in urologic outcomes."
Dr. St. Sauver presented the data at the AUA annual meeting in San Francisco.
Observations made after a diagnosis of prostate cancer or treatment for BPH were removed from the analysis, leaving a total of 648 men with a median follow-up of 8 years.
Researchers measured serum hormone levels of estradiol, total testosterone, and bioavailable testosterone from fresh and frozen serum samples. Hormone levels were standardized to round nine levels. Changes in hormone levels and urologic outcomes were assessed using linear mixed-effects regression models, while associations between changes in hormones and urologic outcomes were assessed with Spearman correlations and multiple linear regression.
T decline highest in older men
Not surprisingly, total testosterone levels declined with age, Dr. St. Sauver reported, although the decline was slow and modest at a mean of 0.19% per year. The rate of decline was highest among older men in the study cohort.
"We were not just interested in hormone levels, but in the rate of change," Dr. St. Sauver explained.
There was no obvious pattern to changes in estradiol levels, she added. Bioavailable testosterone showed a faster rate of decline in younger men.
Prostate volume increased in a linear fashion as age increased. Maximum urinary output decreased slightly from age 40 to 59, then began a sharper drop to age 70 and older. The rate of LUTS increased very slightly to age 50 to 59, increased to age 60 to 69, then held steady to age 70 and older.
Researchers found no association between total testosterone and prostate volume or baseline hormone levels. LUTS scores worsened more quickly in men who started with higher baseline scores and urinary output declined fastest in men who had the lowest output at the beginning of the study. Rapid declines in testosterone levels were associated with worsening LUTS scores and decreased maximum flow, but there was no association with prostate volume.
"This is clinically interesting, because a lower hormone baseline gave a faster decline," Dr. St. Sauver said. "But since we just followed three hormones, we are probably missing associations. There may be other age-related factors at work as well."