Prospective Study of Serum Dihydrotestosterone and Subsequent Risk of Benign Prostatic Hyperplasia in Community Dwelling Men: The Rancho Bernardo Study

PurposeLittle is known about midlife serum levels of dihydrotestosterone and other androgens before the onset of clinical benign prostatic hyperplasia in community dwelling older men.Materials and MethodsWe measured sex steroid hormones between 1984 and 1987 in the Rancho Bernardo Study. Between 1992 and 1996 surviving participants were evaluated for benign prostatic hyperplasia at followup clinic visits. Benign prostatic hyperplasia was defined as a history of noncancer prostate surgery or a medical diagnosis of benign prostatic hyperplasia. Regression modeling was used to examine associations of serum hormone measures with benign prostatic hyperplasia.ResultsIn 340 surviving participants with complete data available and no history of prostate cancer or benign prostatic hyperplasia at baseline mean ± SD age was 64 ± 9 years and mean followup was 8.4 ± 0.8 years. Men who reported benign prostatic hyperplasia during followup were older at baseline than those who did not (p <0.001). Higher baseline serum dihydrotestosterone was associated with an increased risk of benign prostatic hyperplasia. The OR for the second, third and fourth quartiles of dihydrotestosterone was 1.83 (95% CI 0.96–3.47), 1.50 (0.79–2.85) and 2.75 (1.46–5.19), respectively (p trend = 0.02). A higher testosterone-to-dihydrotestosterone ratio was associated with a 42% decreased risk of benign prostatic hyperplasia when comparing the top 3 quartiles to the first quartile (OR 0.58, 95% CI 0.35–0.97, p = 0.04). Higher dehydroepiandrosterone was associated with an increased benign prostatic hyperplasia risk (p = 0.05).ConclusionsCommunity dwelling men show a stepwise increase in benign prostatic hyperplasia risk with higher midlife serum dihydrotestosterone. These data justify investigations of 5α-reductase inhibitors for primary prevention of benign prostatic hyperplasia.