Dutasteride improves bone mineral density in male patients with lower urinary tract symptoms and prostatic enlargement: a preliminary study

Introduction: We studied the effect of dutasteride on bone mineral density (BMD) in aging male patients with lower urinary tract symptoms (LUTS) and prostatic enlargement.

Methods: We prospectively studied 17 patients with LUTS and prostatic enlargement. Before and 1 year after dutasteride (0.5?mg daily), we assessed International Prostate Symptom Score (IPSS), prostatic volume (PV), serum prostatic-specific antigen (PSA) and testosterone. BMD in the lumbar and femur was measured by DEXA method.

Results: Dutasteride significantly reduced PV (from 51?±?24 to 34?±?17?ml, p?p?p?2, p?2, p?2, p?Conclusions: Dutasteride has a potential to improve BMD with elevation of serum testosterone in aging male patients with LUTS and prostatic enlargement.     

Effects of testosterone replacement therapy on hypogonadal men with osteopenia or osteoporosis: a subanalysis of a prospective randomized controlled study in Japan (EARTH study)

Objective: We investigated the effects of testosterone replacement therapy (TRT) on bone mineral density (BMD) among hypogonadal men with osteopenia/osteoporosis.

Methods: From our previous EARTH study population, 74 patients with a clinical diagnosis of osteopenia or osteoporosis and hypogonadism were included in this study, as the TRT (n?=?35) and control (n?=?34) groups. The TRT group was administered 250?mg of testosterone enanthate injection every 4 weeks for 12 months. The BMD, waist circumference, body mass index, body fat percentage, and muscle volume were measured at baseline and at 12 months. Blood biochemical data, including total cholesterol, triglycerides, HDL-cholesterol, hemoglobin A1c, and adiponectin values were also evaluated.

Results: At the 12-month visit, BMD significantly increased in both groups. However, comparisons on changes of parameter values from baseline to the 12-month visit between the TRT and control groups were significantly different in BMD (5.0?±?5.0 vs. 3.0?±?3.2; p?=?.0434) and in adiponectin value (?0.90?±?3.33 vs. 0.10?±?2.04; p?=?.0192). There were no significant changes in other parameters.

Conclusions: TRT for 12 months could improve BMD with a decrease in adiponectin levels among hypogonadal men with osteopenia/osteoporosis.     

The relationship between serum total testosterone and free testosterone levels with serum hemoglobin and hematocrit levels: a study in 1221 men

Objective: To investigate the relationship between serum total testosterone (TT) and free testosterone (FT) levels in men with anemia.

Methods: We reviewed the records of 1221 subjects between March 2009 and December 2014. All the subjects’ blood samples were drawn for TT and FT assays. Their serum hemoglobin (Hb) and serum hematocrit (Hct) levels were measured. The primary objective of our study was to investigate the association between TT and FT levels with Hb and Hct levels.

Results: The mean age was 59.82?±?12.71 years. The mean TT and FT levels were 4.54?±?2.02?ng/mL and 10.63?±?3.69?pg/mL, respectively. The mean Hb and Hct levels were 14.72?±?1.34?g/dL and 43.11?±?3.75%, respectively. Subjects with low TT (<2.35?ng/mL) had low Hb and Hct levels (p?p?Conclusions: Subjects with low TT and FT levels had low Hb and Hct levels. This suggests that TT and FT play a significant role in erythropoiesis. Testosterone replacement therapy may be effective in men with hypogonadism to reduce the incidence of anemia.     

Total testosterone levels are correlated to metabolic syndrome components

Introduction: Metabolic syndrome (MetS) is a constellation of interrelated risk factors of metabolic origin. Some studies suggest a possible link between low total testosterone (TT) levels and the presence of MetS.

Aim: To analyze the strength and independence of associations between TT and MetS components in non-diabetic men.

Methods: In this cross-sectional study, 143 non-diabetic men older than 40 were analyzed.

Main outcomes measure: Blood samples were collected to evaluate metabolic profile and TT levels. MetS was defined as the presence of three or more of the following characteristics: fasting blood glucose levels?≥?100?mg/dL, triglyceride?≥?150?mg/dL, HDL-c??102?cm.

Results: Mean age of the study population was 61.5?±?8.61 years old. MetS was present in 47.9% of the individuals. Thirty-four men had low TT and MetS was observed in 23 (70%) against 50 (46%) in those with normal TT (≥?300?ng/dL) (OR 4.94, p?p?=?0.03) and HDL-c (Beta: 0.19; p?=?0.04) remained significantly correlated with TT levels.

Conclusions: Low TT levels were associated with MetS diagnosis. Abdominal obesity was the MetS component independently correlated to low TT levels.     

Evaluation of sex hormone levels and some metabolic factors in men with coronary atherosclerosis

Background Because of the great controversy over the role of androgens in the pathogenesis of atherosclerosis, we investigated the relationship between serum sex hormone levels and angiographically confirmed coronary artery disease in men.

Material and methods We investigated 86 men aged 40–60 years, 56 with coronary artery disease and 30 healthy men, matched by age, as a control group. Body mass index and waist to hip ratio were calculated and total body fat mass and percentage of abdominal deposit were investigated by dual-energy X-ray absorptiometry (Dpx (?+?) Lunar, USA). The serum levels of sex hormones and insulin were measured using commercial radioimmunoassay and IRMA (by SHBG) kits (DPC, USA). The serum levels of lipids and glucose were assessed by means of enzymatic methods.

Results Men with coronary artery disease had lower total testosterone levels (17.01?±?6.42 vs. 19.37?±?6.58?nmol/l; p?<?0.05), testosterone/estradiol ratio (228.5?±?88.5 vs. 289.8?±?120.1; p?<?0.05) and free androgen index (FAI) (59.49?±?14.79 vs. 83.03?±?25.81; p?<?0.0001), and higher levels of estrone (49.5?±?27.7 vs. 36.6?±?12.7?pg/ml) than men in the control group. Moreover, men with coronary artery disease were more insulin-resistant than controls and had an atherogenic lipid profile. There was an inverse correlation (p?<?0.05) between testosterone level and serum level of glucose (r?=??0.29), triglycerides (r?=??0.37), body mass index (r?=??0.55), waist (r?=??0.43), total body fat mass (r?=??0.3) and fasting insulin resistance index. A significant positive association (p?<?0.05) was found between testosterone and the quantitative insulin sensitivity check index and high density lipoprotein cholesterol level in serum (r?=?0.26).

Conclusions Low levels of total testosterone, testosterone/estradiol ratio and free androgen index and higher levels of estrone in men with coronary artery disease appear together with many features of metabolic syndrome and may be involved in the pathogenesis of coronary atherosclerosis.     

Mission Statement

Aim.?To investigate sex hormone and androgen receptor (AR) levels and to evaluate their relationship with diabetes mellitus (DM) in senile men.

Methods.?The cross-sectional study included 492 elderly men comprising 104 healthy subjects (mean age 71.4 ± 5.2 years), 259 subjects without DM (71.5 ± 5.0 years) and 129 DM patients (73.0 ± 6.3 years). Plasma concentrations of total testosterone (TT), free testosterone (FT), dehydroepiandrosterone sulphate, sex hormone-binding globulin (SHBG), estradiol (E₂), luteinising hormone) and follicle-stimulating hormone (FSH) were determined. AR-positive cells were measured by flow cytometry.

Results.?TT concentrations were significantly lower in the DM group (13.8 ± 4.7 nmol/l) than in the healthy (17.1 ± 6.1 nmol/l) and non-diabetes groups (15.8 ± 6.0 nmol/l; all P < 0.01). FT, SHBG, AR-positive proportion (AR%) and AR fluorescence intensity showed a decreasing trend among the healthy, non-DM and DM groups, but the differences were not significant. TT, E₂, E₂/testosterone and SHBG were negatively correlated with blood glucose. SHBG was positively correlated and TT and AR% were negatively correlated with the course of DM. Logistic multiple regression analysis revealed that age, waist/hip ratio, FSH, SHBG and AR% are potential risk factors for DM.

Conclusions.?Low levels of TT, SHBG and AR may be potential risk factors for DM in elderly men.     

Interleukin-18 and testosterone levels in men with metabolic syndrome

Objective: Interleukin 18 (IL-18) is an adipokine associated with obesity. Data about the relationship of IL-18 to the metabolic syndrome (MS) are still scarce. Low testosterone (T) levels are common in men with MS, but we did not find data about the levels of IL-18 in men with low T. The aim of this study was to determine the levels of IL-18 in men with MS with or without low T.

Patients and methods: A total of 251 men were included in the study. Of them 218 had MS (IDF 2005) and they were divided according to their morning total testosterone (TT) level (cutoff 10.4?nmol/l) into two groups: MS-low T (N?=?84) and MS-normal T (N?=?134). The control group consisted of 33 men without MS and low T. IL-18 was determined in serum using enzyme-linked immunosorbent assay. A small group of eight men with MS and low T levels received testosterone therapy for three months and physical and laboratory parameters were monitored at the end of that period.

Results: MS men were at mean age (±SD)?=?53.77?±?9.59 years; body mass index (BMI)?=?34.0?±?6.3?kg/m²; and TT?=?12.59?±?5.66?nmol/l. The control group was at age?=?52.12?±?5.2 years (NS); BMI?=?25.6?±?2.4?kg/m² (p?p?p?p?p?p?Conclusions: In this study, higher IL-18 levels were found in the presence of MS compared to healthy men, but they did not differ between men having MS with or without LOH.     

Effects of oral testosterone undecanoate therapy on bone mineral density and body composition in 322 aging men with symptomatic testosterone deficiency: a 1-year,randomized, placebo-controlled,dose-ranging study

Abstract

Objective: We investigated the effects of oral testosterone undecanoate (TU) on bone mineral density (BMD), lean body mass (LBM) and body fat mass (BFM) in aging men with symptomatic testosterone deficiency (TD).

Methods: Three hundred twenty-two men ≥50 years with TD symptoms and calculated free testosterone <0.26?nmol/L participated in a multicenter, double-blind, placebo-controlled trial. Patients were randomized to placebo, oral TU 80?mg/d, oral TU 160?mg/d, or oral TU 240?mg/d, administered as divided doses with normal meals. BMD of the hip and lumbar spine were evaluated by dual energy X-ray absorptiometry (DEXA), and body composition (LBM and BFM) by whole body DEXA.

Results: Oral TU significantly increased BMD at Month 12 at the lumbar spine (240?mg/d), total hip (240?mg/d), and trochanter and intertrochanter (160 and 240?mg/d) compared with placebo. Oral TU significantly increased LBM at Months 6 and 12 for all oral TU groups compared with placebo. BFM significantly decreased at Month 6 (all oral TU groups) and Month 12 (160?mg/d) compared with placebo. The effects on BMD and body composition showed a clear dose response.

Conclusions: Treatment with oral TU led to improvement in BMD, LBM and BFM in aging men with symptomatic TD.     

A four-year efficacy and safety study of the long-acting parenteral testosterone undecanoate

Introduction. This is a four-year follow-up of 25 men who received parenteral testosterone undecanoate (TU), 1000 mg every 12 weeks for at least four years. This study was a continuation of a 30-week study wherein the effects of TU had been compared to those of parenteral testosterone enanthate.

Methods & Results. Plasma testosterone (T) trough values of the injection interval of 12 weeks): median 11.9 – 15.9 nmol/L (N 10.0–30.0). E2 and SHBG were stable. Body weight, BMI, waist-to-hip ratio remained stable. Total cholesterol, and triglycerides were unchanged but plasma LDL declined while HDL, after an initial reduction over the first 30 weeks, had increased significantly after three years. Leptin levels, bone mineral density, blood pressure, liver function tests, haemoglobin and haematocrit levels remained stable without values above the upper limit of normal. Over the first 12 months of the study there was an increase in prostate volume from 19.7 ± 8.8 mL to 22.0 ± 8.4 mL (p < 0.05) but thereafter volumes remained stable, paralleled by an increase in PSA from 0.67 ± 0.38 µg/dL to 0.75 ± 0.35 µg/dL (p < 0.05) without any further changes after 12 months.

Conclusion. TU appears to be a stable and safe treatment modality of hypogonadal men.     

Effects of testosterone supplementation on prevention of age-related penile remodeling

Abstract

Erectile dysfunction develops among 46.2% of men between 40 and 70 years. Studies demonstrated substitution on detrusor muscle by collagen due testosterone deprivation. It is clear the correlation among aging and oxidative stress, accelerating apoptosis process in many tissues. This study aims to demonstrate the collagen substitution over the muscle fibers on muscle structure of rat’s penis and the effects of testosterone supplementation. Sixteen senescent Wistar rats were divided into two groups: treatment (receiving standard supplementation testosterone dose) and control (receiving equivalent saline solution). Testosterone was dosed on D0 and D56 of study. All penises were prepared with picrosirius colored histology; stereology was applied to determine the volumetric density of collagen fibers (Vv). Analysis of variance demonstrated testosterone group’s replacement therapy to be effective, while the androgenic decline continued by the time of experiment in control group (p?<?0.05). Testosterone group had Vv of 20.6%, lower than control group (47.8%); t-test (p?<?0.001). Pearson’s correlation demonstrated an inverse correlation between the Vv and testosterone’s levels (p?<?0.001). This is a pioneer study on demonstration of structural alterations over the cavernous corpora muscle caused by deprivation of testosterone on elderly rat. These finding implicate that the testosterone levels can influence, not only the libido, but also the erectile function.     

Association between testosterone levels and the metabolic syndrome in adult men

Abstract

Objective: To evaluate the relationship between testosterone levels and the metabolic syndrome (MS) in men older than 45 years.

Methods: Six hundred and sixty men (45–70 years) selected from 2906 participants of a population screening for prostate cancer were included in this study. Testosterone and the components of MS were assessed in all men. MS was diagnosed according to NCEP-ATP III criteria. Triglycerides (TG)/HDL-cholesterol (chol) index was calculated.

Results: The presence of MS was inversely associated with testosterone (χ², p?<?0.001), independently of age (OR 0.802, CI 95%: 0.724–0.887, p?<?0.0001). Hypertension was the most frequent abnormality observed followed by elevated TG and waist circumference (WC). Testosterone correlated positively with HDL-chol (r: 0.14, p?<?0.0001) and negatively with body mass index (BMI)(r: ?0.29, p?<?0.0001), WC (r: ?0.26, p?<?0.0001), TG (r: ?0.20, p?<?0.0001), TG/HDL-chol (r: ?0.20, p?<?0.0001), glucose (r: ?0.11, p?=?0.005) and MS score (r: ?0.23, p?<?0.0001).

Conclusions: Our results show that in men older than 45 years, as long as testosterone levels decline, the prevalence of MS increases, independently of age. The correlations found between testosterone and four of the five components of MS, as well as with BMI and TG/HDL-chol ratio, a surrogate marker of insulin resistance, suggest considering male hypogonadism as a determinant of developmental abnormalities typical of MS.     

Effects of acute androstenedione supplementation on testosterone levels in older men

The purpose of the study was to examine the effects of acute androstenedione supplementation on hormone levels in older men at rest and during exercise. Men (n?=?11) between the ages of 58 and 69 were divided into an experimental (n?=?6; 62.33?±?2.57 y) and control (n?=?5; 60.2?±?1.02 y) groups. Each participant received an oral 300?mg dose of either androstenedione (experimental) or a cellulose placebo (control) for 7 d. Pre- and post-supplementation participants completed two separate, 20-min strength tasks consisting of leg extension and leg curls at different percentages of their 10-RM. Researchers collected blood samples pre-, during, and post-exercise. Blood samples were analyzed for testosterone, androstenedione, and estradiol levels. The researchers found a significant difference between pre- (4.36?±?56?ng/mL) and post- (5.51?±?0.35?ng/mL) testosterone levels, as well as pre- (0.88?±?0.20) and post- (7.46?±?1.25) androstenedione levels, but no significant differences between pre- and post-estradiol levels for either group. It appears that short-term androstenedione supplementation augmented acute testosterone responses to resistance exercise in older men. However, further study of this supplement is needed to determine any potential it may have in mitigating andropause.     

Anabolic-androgenic steroid effects on early morbid symptoms after open prostatectomy: A pilot study

Objectives.?Anabolic-androgenic steroids such as Nandrolone phenpropionate (NP) dramatically improve the tolerance to acute stress conditions, strength, and subsequently the quality of life in elderly men. We hypothesize that preoperative pulse-dose supraphysiological NP administration might improve the early morbid symptoms in older patients undergoing open prostatectomy.

Methods.?From 2005 to 2006, 54 patients with a mean age of 70 years, diagnosed as benign prostatic hyperplasia and hospitalized for open prostatectomy were enrolled in the study. They were randomly selected to receive preoperative supraphysiological NP (100 mg, intramuscularly, pulse-dose) or sesame oil placebo, prospectively. Early postoperative morbid symptoms including subjective urinary symptoms (dysuria, bladder retention sensation), incision site pain and general satisfaction of their current urinary condition were assessed by a 6-point scale, self-administrated questionnaire at 24 and 48 h, postoperatively. The sex hormone binding globulin and the testosterone levels were also measured.

Results.?The 24-h postoperative symptoms were significantly reduced in the NP group compared to the placebo (6.18 ± 2.81 versus 9.77 ± 2.15; P < 0.001). The postoperative symptoms were reported to have a decline in the 48 h following operation, though was calculated to be statistically insignificant (4.48 ± 2.32 versus 5.55 ± 1.84; P = 0.06). There was no complication attributed to NP therapy.

Conclusions.?The data supported the hypothesis that the preoperative anabolic steroid supplements (such as NP) could result in a better postoperative endurance in elderly men undergoing open prostatectomy. Further studies, longer and repeated pulse injections in a larger number of older men are mandatory to prove the claim.     

The impact of testosterone replacement therapy on glycemic control,vascular function,and components of the metabolic syndrome in obese hypogonadal men with type 2 diabetes

Objective: This study set out to assess effects of testosterone replacement therapy (TRT) on parameters of metabolic syndrome and vascular function in obese hypogonadal males with type 2 diabetes mellitus (DM2).

Study design: Fifty-five obese hypogonadal diabetic males on oral hypoglycemic treatment were enrolled into this one-year, double-blind, randomized, placebo-controlled clinical study. Group T (n?=?28) was treated with testosterone undecanoate (1000?mg i.m. every 10?weeks) while group P (n?=?27) received placebo.

Methods: Anthropometrical and vascular measurements – flow-mediated dilatation (FMD) and intima media thickness (IMT) – biochemical and hormonal blood sample analyses were performed at the start of the study and after one year. Derived parameters (BMI, HOMA-IR, calculated free testosterone (cFT) and bioavailable testosterone (BT)) were calculated.

Results: TRT resulted in reduction of HOMA-IR by 4.64?±?4.25 (p?p?p?=?.005).

Conclusion: TRT normalized serum testosterone levels, improved glycemic control and endothelial function while exerting no ill effects on the study population.     

Age influences anthropometric and fitness-related predictors of bone mineral in men

Objective. This study assessed the influence of age on the predictors of bone mineral in men.

Methods. Middle-age (n = 41, 54 ± 4 yrs) and older (n = 40, 69 ± 5 yrs) men underwent grip and knee extensor strength tests, total body dual-energy X-ray absorptiometry with regional analyses and a graded exercise treadmill test.

Results. Bone-free lean mass (BFLM) and, to a lesser extent, fat mass (FM) were correlated with bone mineral variables in middle-age men. In older men, BFLM and, to a lesser extent, FM were related to bone mineral content (BMC) at most sites, but inconsistently to bone mineral density (BMD). Knee extensor strength related to bone mineral (BMC and BMD) at most sites in middle-age men, but none in older men. Grip strength inconsistently related to bone mineral in both groups. Aerobic capacity related to bone mineral in middle-age men, but none in older men. In multiple regression, body weight or BFLM predicted bone mineral in middle-age men (R² = 0.33–0.68) and BMC in older men (R² = 0.33–0.50). Predictors of BMD were inconsistent in older men.

Conclusions. Relationships of body composition, muscular strength and aerobic capacity to bone mineral are stronger in middle-age versus older men.     

Association between serum levels of testosterone and biomarkers of subclinical atherosclerosis

Objective: To investigate the association between serum levels of testosterone and biomarkers of subclinical atherosclerosis based on data from 119 middle-aged men of the general population.

Methods: Testosterone, Apolipoprotein A-1 (ApoA-1), Apolipoprotein B (ApoB), Apolipoprotein B-to-Apolipoprotein A-1 ratio (ApoB-to-ApoA-1), high-sensitive C-reactive protein (hsCRP), and fibrinogen levels were measured. Data were also gathered based on age, BMI, waist circumference, smoking, alcohol consumption, and family history of cardiovascular diseases. Men were classified into two groups based on testosterone levels: hypogonadal (testosterone ≤12?nmol/L) and eugonadal men (testosterone >12?nmol/L).

Results: When compared to eugonadal, the hypogonadal men were significantly older (56?years vs. 55?years, p?=?.03), had greater BMI (28?kg/cm² vs. 26?kg/cm², p?=?.01), and higher waist circumference (104?cm vs. 100?cm, p?=?.01). Moreover, ApoB, ApoB-to-ApoA-1 ratio, and hsCRP were significantly higher in hypogonadal men compared to eugonadal men (1.1?g/L vs. 1.0?g/L, p?=?.03), (0.8 vs. 0.7, p?=?.03), (3.3?mg/L vs. 2.0?mg/L, p?=?.01), respectively. On the other hand, ApoA-1 and fibrinogen levels did not differ significantly between groups (p?>?.05). In an adjusted multivariate regression analysis model, only ApoB showed a significant negative association with testosterone levels (β?=??0.01; 95% CI?=??0.02, ?1.50; p?=?.04).

Conclusion: Testosterone levels showed an inverse relation to ApoB, a biomarker implicated in subclinical atherosclerosis. These findings support the hypothesis that low testosterone levels play a role in atherosclerosis.     

Visceral adiposity index is associated with premature ejaculation inversely: a cross-sectional study

Objective: Visceral adiposity index (VAI) is a novel indicator for the assessment of visceral obesity. In this study, we aimed to evaluate the relationship between VAI and premature ejaculation (PE).

Materials and method: A total of 300 men were included in the study. Hundred and fifty men with PE and 150 men without PE (control). All men were evaluated for PE by premature ejaculation diagnostic tool (PEDT). VAI levels were calculated using body mass index (BMI), high density lipoprotein and triglyceride (TG) levels.

Results: Mean age of the study groups was 34.3?±?5.2 (30–60) years and the mean age of the controls were 35.9?±?5.3 (30–60) years. The men with PE had lower BMI, TG levels, waist circumference (WC) and higher high-density lipoprotein-cholesterol (HDL-C) levels. Mean VAI level was 4.13?±?0.7 in study group and 5.72?±?1.6 in control group, respectively. VAI levels were statistically higher in men without PE (p?Discussion: Our cross-sectional study demonstrated a negative correlation between VAI and PE. VAI is superior index for the evaluation and calculation the relationship between obesity and PE.     

The effect of testosterone treatment on prostate histology and apoptosis in men with late-onset hypogonadism

Objectives: To investigate the effect of testosterone replacement therapy (TRT) on prostate histology and apoptosis in men with late-onset hypogonadism (LOH).

Methods: The study included 25 men, having LOH with prostate-specific antigen (PSA) level of 4?ng/ml or less. All patients underwent transrectal ultrasound guided prostate biopsy at baseline, and received testosterone undecanoate treatment for 1 year. Prostate biopsy was repeated at the end of 1 year of testosterone therapy. In addition to clinical and biochemical parameters, prostate histology and apoptotic index (AI) were compared before and after the TRT.

Results: The mean serum total testosterone significantly increased from 178.04?±?51.92 to 496.28?±?103.73?ng/dl (p?=?0.001). No significant differences were observed in serum total and free PSA level, prostate volume and maximal urinary flow rate. There were also no significant differences in AI, stroma/epithelial cells ratio, Ki-67 positive cells and atrophy score of prostate tissue before and after the TRT.

Conclusions: This study demonstrated that TRT did not affect serum PSA level, prostate volume and maximal urinary flow rate. This study also suggests that TRT does not cause the risk for prostate cancer development, because of no significant differences in prostate histology after TRT.     

Caffeine intake is not associated with serum testosterone levels in adult men: cross-sectional findings from the NHANES 1999–2004 and 2011–2012

Objective: The association of caffeine intake with testosterone remains unclear. We evaluated the association of caffeine intake with serum testosterone among American men and determined whether this association varied by race/ethnicity and measurements of adiposity.

Methods: Data were analyzed for 2581 men (≥20?years old) who participated in the cycles of the NHANES 1999–2004 and 2011–2012, a cross-sectional study. Testosterone (ng/mL) was measured by immunoassay among men who participated in the morning examination session. We analyzed 24-h dietary recall data to estimate caffeine intake (mg/day). Multivariable weighted linear regression models were conducted.

Results: We identified no linear relationship between caffeine intake and testosterone levels in the total population, but there was a non-linear association (p_nonlinearity?p_nonlinearity?≤?.03 both) and only among men with waist circumference <102?cm and body mass index <25?kg/m² (p_nonlinearity?Conclusion: No linear association was identified between levels of caffeine intake and testosterone in US men, but we observed a non-linear association, including among racial/ethnic groups and measurements of adiposity in this cross-sectional study. These associations are warranted to be investigated in larger prospective studies.