Evidence Hub

Association of Obesity-Related Hemodilution of Prostate-Specific Antigen, Dihydrotestosterone, and Testosterone

Klaassen Z, Howard LE, Moreira DM, Andriole GL, Terris MK, Freedland SJ

The Prostate, 2017

8,122 participants

Abstract

BACKGROUND: Prostate-specific antigen (PSA) hemodilution is the leading theory for lower PSA values in obese men. However, testosterone and dihydrotestosterone (DHT), which are necessary for PSA production, are reduced in obese men. We assessed the relationship of body mass index (BMI) and PSA, taking into consideration the effect of testosterone and DHT.

METHODS: Among 8,122 participants in Reduction by Dutasteride of Prostate Cancer Events (REDUCE), complete data were available for 7,275. BMI was categorized as normal (<25 kg/m2 ), overweight (25-29.9 kg/m2 ), obese (30-34.9 kg/m2 ), or moderate + severely obese (≥35 kg/m2 ). Associations between BMI, testosterone, and DHT and the outcome variable of PSA were examined using linear regression.

RESULTS: There were 1,964 (27.0%) normal weight, 3,826 (52.6%) overweight, 1,200 (16.5%) obese, and 285 (3.9%) moderately + severely obese patients. With increasing BMI, there was a progressive decrease in PSA (P = 0.02), increase in prostate volume (P < 0.001), and decrease in both testosterone (P < 0.001) and DHT (P < 0.001). Using linear regression, increasing BMI was associated with decreasing serum PSA values. Furthermore, BMI remained inversely associated with PSA after individually adjusting for testosterone and DHT, as well as when adjusting for testosterone and DHT in the same model. Decreased androgen levels accounted for only 19% of the lower PSA in men with higher BMI.

CONCLUSIONS: Only a fraction of lower PSA in obese men…

How strong is the evidence?

Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 8,122 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

Read the paper

Related studies

Go deeper in Evidence Hub

Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.

Open this study Sign up free