https://orcid.org/0000-0002-7459-584X
Dear Editor,
We read with great interest the currently published manuscript by Wu et al. [Citation1] on the possible association between body mass index and testosterone deficiency in aging Chinese men with benign prostate hyperplasia (BPH). BPH and hypogonadism are one of the most common diseases of the aging male. It is a well-known fact that prostate enlargement is an androgen-dependent process, but the paradox of declining testosterone and prostatic hyperplasia during aging still has no clear explanation. Chronic inflammation and the possible implication of other steroidal hormones such as estradiol and other androgens have been proposed as the potential explanations of this paradigm [Citation2,Citation3]. From a general point of view, BPH might be considered to be a part of the metabolic disorders, including dyslipidemia, metabolic syndrome, and obesity.
In this study, the authors examined the clinical data of 795 patients undergoing surgery for BPH. The present study yields valuable results. However, as the authors addressed in the discussion section, these results should be interpreted cautiously because of several reasons. We want to make a further discussion on these problematics, and also present our additional comments.
We entirely agree with authors that the association between body mass index and testosterone deficiency (TD) is not that simple. The link between obesity and TD is reported in several studies, but the pathophysiologic mechanism is yet to be elucidated [Citation4,Citation5]. This study has also proved the complex relation of these two entities. According to the present study, the prostate volume is not associated with body mass index. Contrary to this finding, many studies reported that MetS and its component-obesity was found to be associated with increased risks of benign prostatic enlargement (BPE) and male LUTS [Citation6,Citation7]. At this point, it sounds better to evaluate the obesity and BPH-LUTS association via visceral adiposity, which is a better marker of inflammatory state than BMI. According to a current study [Citation8], increased level of a novel index of abdominal adiposity-visceral adiposity index- was found to be associated with the enhanced prostate volume.
Additionally, the authors performed a logistic regression analysis for factors related to TD, and they found PSA and prostate volume significant. What is the rationale of the association between TD and prostate volume and PSA? Enlarged prostate volume and increased PSA level should not be thought as a potential confounder for TD.
Besides, the present study lacks the clinical signs and symptoms of TD, such as erectile dysfunction, low libido, reduced lean mass, reduced physical performance, reduced bone density. Considering the variability in symptoms and biochemical analysis of TD among the individuals, the clinical perspective of the disease should not be ignored.
As the authors stated, this is a cross-sectional study with a limited possibility of establishing a causal relationship between these conditions. Although the association between obesity and TD seems bidirectional, accumulating evidence suggests that the effects of obesity on testosterone concentrations may be more substantial than the effects of low testosterone on adiposity [Citation9]. Nevertheless, further studies are needed to arrive at a more precise conclusion in this topic.
Furthermore, it is unlikely to generalize the outcomes of the present study as the obesity classification is entirely different in western countries in which BMI of higher than 30 was classified as obese. Accordingly, ethnic differences should also be taken into account while interpreting the results.
Consequently, this study provides valuable data for the association between obesity and TD. However, the practical applications of these data to urologic practice are currently limited. Well designed longitudinal studies are warranted to analyze the causal association between these conditions further.
Disclosure statement
No potential conflict of interest was reported by the authors.
Related Research Data
References
- Wu Y, Xu D, Shen HB, et al. The association between body mass index and testosterone deficiency in aging Chinese men with benign prostatic hyperplasia: results from a cross-sectional study. Aging Male. 2019;6:1–6.
- Hammarsten J, Damber JE, Karlsson M, et al. Insulin and free oestradiol are independent risk factors for benign prostatic hyperplasia. Prostate Cancer Prostatic Dis. 2009;12(2):160–165.
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