Salivary testosterone changes during oral glucose tolerance tests in overweight and obese men - Postprandial or circadian variation?

BACKGROUND

Serum total testosterone (T) decreases postprandially. Postprandial salivary testosterone (SalT) responses, however, have not been studied. We report on the effect of glucose ingestion on fasting SalT concentrations.

OBJECTIVE

To investigate the effect of oral glucose ingestion on fasting SalT.

METHODS

Salivary and blood samples were collected between 09.00 and 09.30 and 2 hours after a 75g oral glucose load in 32 men with mean (standard deviation) age of 52 (5.7) years and body mass index of 32.6 (5.56) kg/m2. Free T and bioavailable testosterone (BAT) were calculated using the Vermeulen equation.

RESULTS

Two hours following oral glucose, there was a decrease in fasting mean (standard deviation) SalT [178.2 (56.6) versus 146.0 (42.2) pmol/L; P = .0003], serum cortisol [332 (105.0) versus 239 (75.3) nmol/L; P = <0.0001], prolactin [193 (75.0) versus 127 (55.9) mIU/L; P = <0.0001] and TSH [1.60 (0.801) versus 1.16 (0.584) mIU/L; P = <0.0001]. Plasma glucose increased [6.2 (0.72) versus 8.1 (3.71) mmol/L; P = .0029]. Serum total T, SHBG, albumin, Free T, BAT, gonadotrophins and FT4 remained unchanged.

CONCLUSIONS

SalT decreased postprandially. A concomitant decrease in serum cortisol, prolactin and TSH reflecting diurnal variation offers an alternative explanation for the decrease in SalT independent of food consumption. Further studies are required to determine whether morning temporal changes in SalT are related to food consumption or circadian rhythm or both.

Glucose ingestion does not lower testosterone concentrations in men on testosterone therapy

Oral calorie intake causes an acute and transient decline in serum testosterone concentrations. It is not known whether this decline occurs in men on testosterone therapy. In this study, we evaluated the change in testosterone concentrations following oral glucose ingestion in hypogonadal men before and after treatment with testosterone therapy. This is a secondary analysis of samples previously collected from a study of hypogonadal men with type 2 diabetes who received testosterone therapy. Study participants (n = 14) ingested 75 grams of oral glucose, and blood samples were collected over 2 h. The test was repeated after 23 weeks of intramuscular testosterone therapy. The mean age and body mass index of study volunteers were 53 ± 8 years and 38 ± 7 kg/m2, respectively. Following glucose intake, testosterone concentrations fell significantly prior to testosterone therapy (week 0, p = 0.04). The nadir of testosterone concentration was at 1 h, followed by recovery to baseline by 2 h. In contrast, there was no change in testosterone concentrations at week 23. The change in serum testosterone concentrations at 60 min was significantly more at week 0 than week 23 (-11 ± 10% vs 0 ± 16%, p = 0.05). We conclude that oral glucose intake has no impact on testosterone concentrations in men on testosterone therapy. Endocrinology societies should consider clarifying in their recommendations that fasting testosterone concentrations are required for the diagnosis of hypogonadism, but not for monitoring testosterone therapy.

Greater Ecologically Assessed Positive Experiences Predict Heightened Sex Hormone Concentrations Across Two Weeks in Older Adults

OBJECTIVES

Sex hormones are important components of healthy aging, with beneficial effects on physical and mental health. Positive experiences such as elevated mood, lowered stress, and higher well-being also contribute to health outcomes and, in younger adults, may be associated with elevated sex hormone levels. However, little is known about the association between positive experiences and sex hormones in older adults.

METHODS

In this study, older men and women (N = 224, 70+ years of age) provided blood samples before and after a 2-week period of ecological momentary assessment (EMA) of positive and negative experiences (assessed based on self-reporting items related to affect, stress, and well-being). Concentrations of a panel of steroid sex hormones and glucocorticoids were determined in blood.

RESULTS

Higher levels of positive experiences reported in daily life across 2 weeks were associated with increases in free (biologically active) levels of testosterone (B = 0.353 [0.106, 0.601], t(221.3) = 2.801, p = .006), estradiol (B = 0.373 [0.097, 0.649], t(225.1) = 2.645, p = .009), and estrone (B = 0.468 [0.208, 0.727], t(224.3) = 3.535, p < .001) between the start and the end of the 2-week EMA period.

DISCUSSION

These findings suggest that sex hormones may be a pathway linking positive experiences to health in older adults.

Fasting Versus Non-Fasting Total Testosterone Levels in Women During the Childbearing Period

Background Total testosterone in men should be measured in the fasting state early in the morning with at least two samples according to guidelines. For women, no such a recommendation is available despite the importance of testosterone in this demographic. The aim of this study is to evaluate the effect of fasting versus non-fasting state on the total testosterone levels in women during the reproductive period. Methods This study was conducted at Faiha Specialized Diabetes, Endocrine and Metabolism Center in Basrah, (Southern Iraq) between January 2022 to November 2022. The total enrolled women were 109; their age was 18-45 years. The presentation was for different complaints; 56 presented for medical consultation with 45 apparently healthy women accompanying the patients as well as eight volunteering female doctors. Testosterone levels were measured by electrochemiluminescence immunoassays using the Roche Cobas e411 platform (Roche Holding, Basel, Switzerland). Two samples were collected from each woman; one was fasting and another was non-fasting the following day, and all samples were taken before 10 am. Results  For all of the participants, the mean ± SD fasting was significantly higher as compared to the non-fasting testosterone (27.39±18.8 ng/dL and 24.47±18.6 ng/dL respectively, p-value 0.01). The mean fasting testosterone level was also significantly higher in the apparently healthy group, (p-value 0.01). In women who presented with hirsutism, menstrual irregularities and or hair fall, no difference was seen in the testosterone levels between fasting and non-fasting states (p-value 0.4).  Conclusion In the apparently healthy women of childbearing age, serum testosterone levels were higher in the fasting versus the non-fasting states. In women who presented with complaints of hirsutism, menstrual irregularities, and or hair fall, the serum testosterone levels were not affected by the fasting states.

Is a fasting testosterone level really necessary for the determination of androgen status in men?

BACKGROUND

As circulating testosterone may be suppressed in the post-prandial state, it has been recommended that measurements are carried out with the patient fasted.

OBJECTIVES

In this regard, we assessed the effect of fasting/non-fasting status on total testosterone (T) levels in men.

MATERIALS AND METHODS

Data was collected in a single UK Hospital in men with two serum T requests taken within a 6-month period of each other and sampled at a time of day ≤ 2 h apart. Three groups were established, with T levels compared via signed-rank test in men with both a fasting and non-fasting sample (Group 1; n = 69), and in men with paired non-fasting (Group 2; n = 126) and paired fasting (Group 3; n = 18) samples. The differences in T levels between the paired samples was compared between the three groups using the rank-sum test and also via multiple regression analysis with the groups factorised.

RESULTS

Median (Interquartile Range, IQR) age did not vary significantly between Groups 1, 2 and 3 at 49 (38-56), 51.5 (42-60) and 51.5 (40-59) years, respectively. No significant difference (p = 0.89) was found between the T levels in Group 1 with non-fasting (median (IQR) T = 11.1 (9.3-13.6) nmol/L) versus fasting samples T = 10.8 (8.9-14.1) nmol/L). Paired T levels did not significantly differ in each of the other two groups (2 and 3). There was no significant association between the differences in paired T levels between the three groups, even when the model was adjusted for age and time, with Group 1 (as reference) versus Group 2 (p = 0.79) and versus Group 3 (p = 0.63).

DISCUSSION

We found no significant differences between fasting and non-fasting T levels. A definitive confirmatory study is required to determine whether fasting status is necessary to diagnose hypogonadism.

CONCLUSION

Non-requirement of fasting status when checking testosterone levels would remove a major hurdle in the diagnosis of hypogonadism.

Effects of intravenous and oral di(2-ethylhexyl) phthalate (DEHP) and 20% Intralipid vehicle on neonatal rat testis, lung, liver, and kidney

The highest human exposures to the plasticizer di(2-ethylhexyl) phthalate (DEHP) occur through intravenous (iv) exposure from medical procedures. Rodent toxicity studies, mainly using oral exposures, have identified male reproductive toxicity after developmental exposure to DEHP as the primary concern. Other organs are also affected by DEHP and route may influence the degree of target organ involvement. Cammack et al. (2003) reported a critical study focused on testicular toxicity using oral and iv exposures of neonatal Sprague-Dawley rats to 60, 300, or 600 mg/kg body weight/day DEHP in Intralipid vehicle. The present study followed the same dosing paradigm and included assessment of additional organs to evaluate the potential utility of this design for DEHP alternatives. Reduction of testis weight was observed in all DEHP treatment groups and germ cell and Sertoli cell toxicity was observed at the two highest doses with both routes. Lung granulomas occurred in all iv DEHP groups, possibly related to increased fat particle size in DEHP lipid emulsions. Lung alveolar development was inhibited after both oral and iv high dose DEHP. Toxicity of oral Intralipid vehicle was observed in germ and Sertoli cells. The lack of such effects after iv vehicle exposure suggested that this may be a gut-mediated effect.

The Effect of Macronutrients on Reproductive Hormones in Overweight and Obese Men: A Pilot Study

Hypogonadal obese men find it difficult to lose weight. We investigated whether the modification of macronutrient intake can alter testosterone levels independently of the body mass index. Fasted overweight or obese fertile men were asked to consume meals of polyunsaturated fats (PUFA), monounsaturated fats (MUFA), refined carbohydrates (CHO, orange juice, OJ), whey and egg albumin and mixed meals of PUFA and CHO, PUFA and egg albumin, and CHO and egg albumin. Blood was collected at fasting, then hourly for 5 h and analysed to determine the levels of testosterone and other hormones. We found PUFA and MUFA or a mixed meal of PUFA and CHO significantly reduced serum testosterone production to a similar degree over a 5 h period. PUFA decreased serum testosterone levels by 3.2 nmol/L after 1 h compared to baseline (p = 0.023), with this suppression remaining significant up to 5 h postprandially (2.1 nmol/L; p = 0.012). The net overall testosterone levels were reduced by approximately 10 nmol/L × h by PUFA, MUFA and PUFA combined with CHO. CHO alone had little effect on testosterone levels, whereas egg albumin was able to increase them (7.4 cf 2.0 nmol/L × h). Therefore, for men wishing to optimize their testosterone levels, it may be wise to avoid a high fat intake, drink liquids such as water or OJ or even consider fasting. ANZCTR, Australia; ACTRN12617001034325.