Association of TyG index with prostate-specific antigen (PSA) in American men: results from NHANES, 2003-2010

BACKGROUND

In recent years, triglyceride-glucose index (TyG) was a new indicator of insulin resistance, and it has been widely reported that it may be associated with serum prostate-specific antigen (PSA) concentrations.

AIMS

We intended to investigate the possible connection between serum PSA concentration and the TyG index.

METHODS

This is a cross-sectional study of adults with complete data on TyG and serum PSA concentrations (ng/ml) from the NHANES, 2003-2010. The TyG index is obtained by the formula below: TyG = Ln [triglycerides (mg/dL) × fasting glucose(mg/dL)/2]. Multivariate regression analysis and subgroup analysis were used to examine the connection between the TyG index and serum PSA levels.

RESULTS

Multiple regression analysis of the weighted linear model showed that individuals with a higher TyG index had lower PSA levels. Subgroup analyses and interaction tests showed no apparent dependence on age, race/ethnicity, BMI, household income ratio, education level, and marital status on this negative association (all interactions p > 0.05).

CONCLUSIONS

TyG index is related to lower serum PSA concentrations in adult men from the USA. Further comprehensive prospective studies are needed to confirm our findings.

Androgens, aging, and prostate health

Due to late onset hypogonadism (LOH), there is an increased usage of testosterone replacement therapy (TRT) in the aging male population. Since prostate is a target organ for androgens and anti-androgenic strategies are used to treat and palliate benign prostate hyperplasia (BPH) and prostate cancer (PC), the prevalence of both increases with age, the possible influence of TRT on prostate health becomes highly relevant. The present review summarizes existing data on the associations between endogenous hormone concentrations and prostate growth and concludes that circulating concentrations of androgens do not appear to be associated with the risks of development of BPH or initiation or progression of PC. The explanation for these findings relates to an apparent insensitivity of prostatic tissue to changes of testosterone concentrations within the physiological range.

The association of pathogenic factors of metabolic syndrome on serum prostate-specific antigen levels: a pilot study

Background

Metabolic syndrome (MetS) and serum prostate-specific antigen (PSA) levels are correlated. To investigate the underlying effect of MetS on PSA levels, the relationship between the major pathogenic factors of MetS and serum PSA levels was studied.

Methods

A total of 506 ostensibly healthy men who underwent routine health check-ups were recruited to this study. We evaluated the effect of the major pathogenic factors of MetS, which included insulin resistance, a subclinical inflammatory state and sexual hormone changes, on serum PSA levels by using linear regression analysis and multivariate analysis after adjusting for age, BMI and prostate volume.

Results

When simultaneously adjusting for age, BMI, prostate volume and high-density lipoprotein cholesterol, serum insulin levels and SHBG levels were inversely correlated with serum PSA levels (P = 0.049 and P = 0.004, respectively), and testosterone levels were positively correlated with serum PSA levels (P = 0.039). In multivariate regression models, serum insulin levels and serum SHBG levels were significantly associated with serum PSA levels (both P < 0.001).

Conclusions

Among the major pathogenic factors of metabolic syndrome, insulin resistance and sexual hormone changes may be the most significant contributors to the decline in serum PSA levels.

Actual lowering effect of metabolic syndrome on serum prostate-specific antigen levels is partly concealed by enlarged prostate: results from a large-scale population-based study

OBJECTIVES

To clarify the lowering effect of metabolic syndrome (MetS) on serum prostate-specific antigen (PSA) levels in a Chinese screened population.

SUBJECTS AND METHODS

A total of 45 540 ostensibly healthy men aged 55-69 years who underwent routine health check-ups at Beijing Shijitan Hospital between 2008 and 2015 were included in the study. All the men underwent detailed clinical evaluations. PSA mass density was calculated (serum PSA level × plasma volume ÷ prostate volume) for simultaneously adjusting plasma volume and prostate volume. According to the modified National Cholesterol Education Programme-Adult Treatment Panel (NCEP-ATP) III criteria, patients were dichotomized by the presence of MetS, and differences in PSA density and PSA mass density were compared between groups. Linear regression analysis was used to evaluate the effect of MetS on serum PSA levels.

RESULTS

When larger prostate volume in men with MetS was adjusted for, both PSA density and PSA mass density in men with MetS were significantly lower than in men without MetS, and the estimated difference in mean serum PSA level between men with and without MetS was greater than that before adjusting for prostate volume. In the multivariate regression model, the presence of MetS was independently associated with an 11.3% decline in serum PSA levels compared with the absence of MetS. In addition, increasing number of positive MetS components was significantly and linearly associated with decline in serum PSA levels.

CONCLUSION

The actual lowering effect of MetS on serum PSA levels was partly concealed by the enlarged prostate in men with MetS, and the presence of MetS was independently associated with lower serum PSA levels. Urologists need to be aware of the effect of MetS on serum PSA levels and should discuss this subject with their patients.

Association between baseline serum glucose, triglycerides and total cholesterol, and prostate cancer risk categories

Lifestyle-related risk factors such as hyperglycemia and dyslipidemia have been associated with several cancers. However, studies exploring their link with prostate cancer (PCa) clinicopathological characteristics are sparse and inconclusive. Here, we investigated the associations between serum metabolic markers and PCa clinicopathological characteristics. The study comprised 14,294 men from the Swedish Apolipoprotein MOrtality RISk (AMORIS) cohort who were diagnosed with PCa between 1996 and 2011. Univariate and multivariable logistic regression were used to investigate the relation between glucose, triglycerides and total cholesterol and PCa risk categories, PSA, Gleason score, and T-stage. Mean age at time of PCa diagnosis was 69 years. Men with glucose levels >6.9 mmol/L tend to have PSA<4 μg/L, while those with glucose levels of 5.6-6.9 mmol/L had a greater odds of PSA>20 μg/L compared to PSA 4.0-9.9 μg/L. Hypertriglyceridemia was also positively associated with PSA>20 μg/L. Hyperglycemic men had a greater odds of intermediate- and high-grade PCa and advanced stage or metastatic PCa. Similarly, hypertriglyceridemia was positively associated with high-grade PCa. There was also a trend toward an increased odds of intermediate risk localized PCa and advanced stage PCa among men with hypertriglyceridemia. Total cholesterol did not have any statistically significant association with any of the outcomes studied. Our findings suggest that high serum levels of glucose and triglycerides may influence PCa aggressiveness and severity. Further investigation on the role of markers of glucose and lipid metabolism in influencing PCa aggressiveness and severity is needed as this may help define important targets for intervention.

The metabolic syndrome is associated with more aggressive prostate cancer

PURPOSE

The aim of this study was to analyze any association between the metabolic syndrome (MetS) and risk of prostate cancer (PCa) and cancer grade among men undergoing radical prostatectomy for PCa.

MATERIALS AND METHODS

50 patients with MetS and 50 patients without MetS who undervent radical prostatectomy (RP) were included in the study. Age at biopsy, height, weight, digital rectal examination (DRE), pre-biopsy PSA levels, prostate volume, histopathologic diagnosis after surgery and Gleason scores were collected data from all patients. Histologic material obtained at biopsy was given a Gleason score; tumours with a Gleason score ≥7 were considered high grade and <7 were considered low grade.

RESULTS

The mean age at the time of biopsy was 63.7 ± 5.94 in patients with MetS and 61.6 ± 6.14 in patients without MetS. Men with MetS had significantly lower PSA levels (p=0.01) (7.21 ± 2.74 and 8.81 ± 2.72, respectively). Also, the men with MetS had higher RP tumor grade (p=0.04).

CONCLUSIONS

Men with MetS undergoing RP have lower PSA levels and have significantly higher grade PCa. We must be careful for screening PCa in patients with MetS. Although the patients had lower PSA levels, they may have high grade disease.

Prostate-specific antigen lowering effect of metabolic syndrome is influenced by prostate volume

OBJECTIVES

To investigate the influence of metabolic syndrome on prostate-specific antigen levels by considering prostate volume and plasma volume.

METHODS

We retrospectively analyzed 4111 men who underwent routine check-ups including prostate-specific antigen and transrectal ultrasonography. The definition of metabolic syndrome was based on the modified Adult Treatment Panel III criteria. Prostate-specific antigen mass density (prostate-specific antigen × plasma volume / prostate volume) was calculated for adjusting plasma volume and prostate volume. We compared prostate-specific antigen and prostate-specific antigen mass density levels of participants with metabolic syndrome (metabolic syndrome group, n = 1242) and without metabolic syndrome (non-prostate-specific antigen metabolic syndrome group, n = 2869). To evaluate the impact of metabolic syndrome on prostate-specific antigen, linear regression analysis for the natural logarithm of prostate-specific antigen was used.

RESULTS

Patients in the metabolic syndrome group had significantly older age (P < 0.001), larger prostate volume (P < 0.001), higher plasma volume (P < 0.001) and lower mean serum prostate-specific antigen (non-metabolic syndrome group vs metabolic syndrome group; 1.22 ± 0.91 vs 1.15 ± 0.76 ng/mL, P = 0.006). Prostate-specific antigen mass density in the metabolic syndrome group was still significantly lower than that in the metabolic syndrome group (0.124 ± 0.084 vs 0.115 ± 0.071 μg/mL, P = 0.001). After adjusting for age, prostate volume and plasma volume using linear regression model, the presence of metabolic syndrome was a significant independent factor for lower prostate-specific antigen (prostate-specific antigen decrease by 4.1%, P = 0.046).

CONCLUSIONS

Prostate-specific antigen levels in patients with metabolic syndrome seem to be lower, and this finding might be affected by the prostate volume.

Metabolic syndrome and benign prostatic enlargement: a systematic review and meta-analysis

OBJECTIVE

To summarise and meta-analyse current literature on metabolic syndrome (MetS) and benign prostatic enlargement (BPE), focusing on all the components of MetS and their relationship with prostate volume, transitional zone volume, prostate-specific antigen and urinary symptoms, as evidence suggests an association between MetS and lower urinary tract symptoms (LUTS) due to BPE.

METHODS

An extensive PubMed and Scopus search was performed including the following keywords: 'metabolic syndrome', 'diabetes', 'hypertension', 'obesity' and 'dyslipidaemia' combined with 'lower urinary tract symptoms', 'benign prostatic enlargement', 'benign prostatic hyperplasia' and 'prostate'.

RESULTS

Of the retrieved articles, 82 were selected for detailed evaluation, and eight were included in this review. The eight studies enrolled 5403 patients, of which 1426 (26.4%) had MetS defined according to current classification. Patients with MetS had significantly higher total prostate volume when compared with those without MetS (+1.8 mL, 95% confidence interval [CI] 0.74-2.87; P < 0.001). Conversely, there were no differences between patients with or without MetS for International Prostate Symptom Score total or LUTS subdomain scores. Meta-regression analysis showed that differences in total prostate volume were significantly higher in older (adjusted r = 0.09; P = 0.02), obese patients (adjusted r = 0.26; P < 0.005) and low serum high-density lipoprotein cholesterol concentrations (adjusted r = -0.33; P < 0.001).

CONCLUSIONS

Our results underline the exacerbating role of MetS-induced metabolic derangements in the development of BPE. Obese, dyslipidaemic, and aged men have a higher risk of having MetS as a determinant of their prostate enlargement.

The illusion of prostate-specific antigen decline in patients with metabolic syndrome and insulin resistance

What's known on the subject? and What does the study add? Studies have shown that PSA is negatively associated with obesity as a result of hemodilution or metabolic effect. Hemodilution could be the main reason for low PSA levels in obese men. However, the intrinsic metabolic effects such as insulin resistance (IR) or metabolic syndrome (MS) on PSA level have not been clearly evaluated although obesity is closely tied to MS and IR. We regarded MS and IR as the pathophysiological cornerstone of metabolic disorder in obesity and analyzed the relationships among MS, IR, and PSA levels, and plasma volume by using the concept of PSA mass, the total circulating PSA protein. PSA mass did not change depending on the severity of the obesity, MS or IR. Even the group with both MS and IR, which could be the most metabolically disturbed in this study, did not have different PSA mass, comparing with the group without any MS or IR. Thus, the decline in PSA level in men with MS or IR can be also explained by increased plasma volume other than any intrinsic metabolic effects.

OBJECTIVE

• To investigate the detailed mechanism of prostate-specific antigen (PSA) decline in metabolic syndrome (MS) and insulin resistance (IR), which lowers the predictive value of the PSA test, we examined the effect of haemodilution and the possibility of an intrinsic metabolic effect.

PATIENTS AND METHODS

• We analysed 28,315 men who underwent routine check-ups. We compared the age-adjusted mean PSA levels in subjects with and without MS before and after adjusting or stratifying the plasma volume. We analysed changes in PSA level, plasma volume and PSA mass according to obesity grade, number of MS components, IR severity and diagnosis of MS, IR or both using an analysis of covariance.

RESULTS

• The PSA levels were lower in the group with MS than in the group without MS (P= 0.001), but this difference disappeared after adjusting or stratifying the plasma volume (P > 0.05 for all). The PSA levels decreased, plasma volume increased, and PSA mass did not change as the number of MS components increased (P= 0.002, P < 0.001, P= 0.55, respectively) or the IR severity increased (P= 0.001, P < 0.001, P= 0.34, respectively). • Similarly, PSA levels were lower, plasma volumes were higher and PSA masses were the same in subjects with MS (P= 0.002, P < 0.001, P= 0.10, respectively), IR (P= 0.018, P < 0.001, P= 0.94, respectively), or both (P= 0.003, P < 0.001, P= 0.86, respectively) than in subjects without those conditions.

CONCLUSION

• The PSA decline in MS and IR may result simply from a haemodilution effect and be unrelated to intrinsic metabolic disturbances. For this reason, PSA levels could be underestimated in patients with MS or IR because of haemodilution.

Serum prostate-specific antigen is better correlated to body surface area than body mass index in a population of healthy Korean men

It has been suggested that the larger vascular volume among obese men causes a dilution effect, decreasing the concentration of serum prostate-specific antigen (PSA). However, plasma volume is proportional to body surface area (BSA) rather than to body mass index (BMI). We determined whether serum PSA level is better correlated to BSA than BMI in a population of ostensibly healthy Korean men. Data from 2604 men who visited our health promotion center were evaluated. All men underwent anthropometric measurements, digital rectal examination, serum PSA determination, and transrectal ultrasound examination. The correlation between serum PSA and other parameters was statistically analyzed. The mean age was 49.9 years and the mean serum PSA level was 1.14 ng/mL. The multivariate analysis revealed that the serum PSA was positively correlated with age, prostate volume, and negatively correlated with BSA only and not with BMI. In addition, BSA, rather than BMI, was the significant factor in predicting the prostate volume. Our results suggest that men with larger BSA (rather than BMI), have larger prostate volumes, and lower serum PSA.