Studies have shown that ED may be an early biomarker of general endothelial dysfunction, atherosclerosis and CVD
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Clinical relevance of optimizing vitamin d s... [J Spec Oper Med. 2014] - PubMed - NCBI - 0 views
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Vitamin D has key impact in performance of soldiers. low vitamin D has been shown to be associated with increased risk for muscle/bone injury, weakness, and poor healing. Low vitamin D has been associated with low Testosterone. Low vitamin D has also been associated with poor cognition, depression and less than optimal recovery after TBI. This follows recent publication that normalization of vitamin D levels increases Testosterone levels.
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The Association between Premature Coronary Art... [Arch Iran Med. 2014] - PubMed - NCBI - 0 views
www.ncbi.nlm.nih.gov/...25065277
low T Testosterone low T low Testosterone free Testosterone Total Testosterone CAD coronary artery disease atherosclerosis heart disease men male hormone hormones health
shared by Nathan Goodyear on 30 Jul 14
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Low free and Total Testosterone levels found to be associated with premature CAD in men. Some confounders were present, which they tried to account for--this should leave some healthy questioning of this study results. That being said, this is not the first time low T has been found to be associated with CAD in men. This study found a statistical significant association with Free and Total Testosterone levels in young men. Another point to consider is the Low T a cause or a biomarker and an effect of poor/declining health? I would so more to the biomarker point.
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The relationship between testosterone, metabolic syndrome, and mean carotid intima-medi... - 0 views
informahealthcare.com/...13685538.2014.958458
low T Testosterone low T low Testosterone aging male metabolic syndrome metabolic syndrome IMT carotid intima-media thickness men hormone hormones
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International Journal of Impotence Research - Obesity, low testosterone levels and erec... - 0 views
www.nature.com/...ijir200842a.html
low T low Testosterone men male hormone hormones ED erectile dysfunction Testosterone diabetes metabolic syndrome obesity
shared by Nathan Goodyear on 27 Jan 15
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testosterone treatment of hypogonadal young and older men improves sexual function, increases lean mass and decreases fat mass
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In men with low serum testosterone (for example, <8 or 230 nmol l−1) with obesity, metabolic syndrome and diabetes mellitus, treatment with testosterone is warranted
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In obese middle-aged men, testosterone treatment reduced visceral adipocity, insulin resistance, serum cholesterol and glucose levels
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testosterone replacement has a favorable impact on body mass, insulin secretion and sensitivity, lipid profile and blood pressure in hypogonadal men with the metabolic syndrome as well as type 2 diabetes mellitus
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Testosterone significantly inhibits lipoprotein lipase activity, which reduces triglycerides uptake into adipocytes in the abdominal adipose tissue
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testosterone treatment decreased endogenous inflammatory cytokines (tumor necrosis factor-α and IL-1β) and lipids (total cholesterol) and increased IL-10 in hypogonadal men
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Testosterone treatment reduced leptin and adiponectin levels in hypogonadal type 2 diabetic men after 3 months of testosterone replacement
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Obesity adversely affects endothelial function and lowers serum testosterone levels through the development of insulin resistance and metabolic syndrome
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Metabolic disturbances as well as production of cytokines and adipokines by inflamed fat cells may be causal factors in the development of ED
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The onset of ED and the associated risk of CVD may be delayed through lifestyle modifications that affect obesity, such as diet and exercise
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Very low testosterone levels contribute to the development of ED in obesity, metabolic syndrome and type 2 diabetes mellitus
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Obesity is associated with low total testosterone levels that can be explained at least partially by lower sex hormone-binding globulin (SHBG) in obese men
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epidemiological studies have shown a negative correlation between BMI and total testosterone and to a lesser extent with free and bioavailable (biologically active) testosterone levels
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Testosterone Deficiency, Cardiac Health, and Older Men - 0 views
www.ncbi.nlm.nih.gov/...PMC4000629
low T low Testosterone hypogonadism men male hormone hormones Testosterone therapy disease diabetes metabolic syndrome osteoporosis HIV infertility opiates
shared by Nathan Goodyear on 27 Jan 15
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Erectile dysfunction is an established marker for future cardiovascular risk and the major presenting symptom leading to a diagnosis of low testosterone
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There is a considerable body of evidence that low testosterone is associated with increased cardiovascular and cancer mortality
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There is considerable evidence of modest cardiac and metabolic benefits that are shown to reduce cardiovascular risk plus sexual, mood, and quality of life changes associated with restoring testosterone levels
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Relationship between Low Free Testosterone Levels and Loss of Muscle Mass : Scientific ... - 0 views
www.nature.com/...srep01818.html
muscle men male hormone Testosterone free Testosterone low T low Testosterone
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Our data confirm that a low FT level is a significant predictor of a risk for loss of appendicular muscle
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These results suggest that a threshold level of FT exists for muscle loss, rather than a dose-response relationship
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In the previous cross-sectional and longitudinal studies of French and American men, no dose-response relationships were reported between T and muscle mass
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A minimal serum level of FT may be needed to preserve muscle mass in men, regardless of race/ethnicity.
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Our result is in line with previous studies that reported a relationship between low FT and low muscle mass in men
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Although a progressive decrease in TT levels with ageing is observed in middle-aged and elderly American men16, 17, the TT levels do not change during ageing in Japanese men
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http://care.diabetesjournals.org/content/33/7/1618.full.pdf - 0 views
care.diabetesjournals.org/...1618.full.pdf
metabolic syndrome low T Testosterone low T low Testosterone SHBG men male hormone hormones
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Longitudinal Effects of Aging on Serum Total and Free Testosterone Levels in Healthy Me... - 0 views
press.endocrine.org/...jcem.86.2.7219
low t low Testosterone Testosterone SHBG FAI free androgen index male hormone hormones aging obesity
shared by Nathan Goodyear on 30 Mar 15
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NUMEROUS CROSS-SECTIONAL INVESTIGATIONS have demonstrated lower concentrations of circulating testosterone (T) and/or free T in older men
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T levels decline at a more or less constant rate, with age, in men, with no period of accelerated decline
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aging in men is associated with decreases in bone mineral density (BMD) (18, 19), lean body and muscle mass
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strength (22, 23) and aerobic capacity (24), as well as with increases in total and abdominal body fat, low-density lipoprotein cholesterol, and/or low-density lipoprotein/high-density lipoprotein cholesterol ratios (25, 26, 27, 28), all of which also occur in nonelderly hypogonadal men
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Most (1, 5, 6, 7, 8, 9), but not all (10, 11, 12), cross-sectional studies have demonstrated a decrease, with age, in total T in men
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total T, but not free T index, tended to decrease with greater BMI is consistent with prior studies showing that obesity is associated with decreases in both SHBG and total T, with an unchanged T-to-SHBG ratio
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The conventional definition for T levels is statistical (values more than 2 sd below the mean), rather than functional. Such a definition does not reflect clinical realities, such as the existence of characteristic individual set points for circulating hormone levels, below which one, but not another, individual may develop metabolic changes of hormone deficiency; nor does it address the concept of reserve capacity, the possibility that persons with hormone levels 2 sd below the population mean still may have adequate hormone concentrations to meet their metabolic needs.
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both T and free T index (a calculated value related to free or bioavailable T) decreased progressively at a rate that did not vary significantly with age, from the third to the ninth decades.
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contrasts with other studies showing diminished free, as well as total, T in with increasing total (48) or abdominal (49) obesity in men.
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Our analysis of date-adjusted T and free T index levels, by decade, showed that relatively high numbers of older men in this generally healthy population had at least one hypogonadal value (defined as below the 2.5th percentile for young men)
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The issue of how properly to define hypogonadism, or indeed any hormone deficiency, remains problematic
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The decrease in free T index was somewhat steeper than that of total T, owing to a trend for an increase in SHBG with age
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It would clearly be better to define the lower limit of normal for a hormone as: the blood level at which metabolic and/or clinical sequelae of hormone deficiency begin to appear, or the level below which definite benefits can be demonstrated for hormone supplementation for a significant proportion of the population
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an effect of aging to lower both total and bioavailable circulating T levels at a relatively constant rate, independent of obesity, illness, medications, cigarette smoking, or alcohol intake
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Article highlights the problems with the definition of low T. This article finds consistent decline in Total Testosterone and FAI with increasing age groups, with a significant portion of men > 60 meeting the required levels for "low T". This study found a decrease in total T and FAI at a consistent rate independent of variables, such as BMI. This study did find a decrease in SHBG and total T with obesity; in contrast to other studies.
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http://onlinelibrary.wiley.com/store/10.1002/tre.178/asset/178_ftp.pdf;jsessionid=F122C... - 0 views
onlinelibrary.wiley.com/...C8E447F14B0F0AE2690DD32.f03t02
prostate cancer prostate cancer low T low Testosterone Testosterone therapy Testosterone
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A revisit of the saturation model of Testosterone therapy and prostate cancer. Review finds Testosterone therapy does not "appear to promote prostate cancer growth". The saturation model is the thought around the AR. At low concentrations, there is a greater sensitivity of Testosterone to AR binding at very low T levels; but above those very low T levels, prostate cancer becomes insensitive to the Testosterone.
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Low Testosterone Levels and Increase... [J Clin Endocrinol Metab. 2012] - PubMed - NCBI - 0 views
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low testosterone and increased inflammation found in men with cancer and cachexia. The question is: if inflammation is part of the development of cancer, and low T is associated with increased inflammation, then we need to be adequately evaluating men for low T and inflammation for prevention. That is true prevention.
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JAMA Network | JAMA: The Journal of the American Medical Association | Effects of Dieta... - 0 views
jama.jamanetwork.com/article.aspx
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Reduced activation and increased ina... [J Clin Endocrinol Metab. 2003] - PubMed - NCBI - 0 views
www.ncbi.nlm.nih.gov/...12843166
inflammation illness thyroid hypothyroid hypothyroidism TSH free T3 rT3 T3:rT3 ratio
shared by Nathan Goodyear on 02 Feb 12
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These observed changes, in correlation with a low T(3)/rT(3) ratio, may represent tissue-specific ways to reduce thyroid hormone bioactivity during cellular hypoxia and contribute to the low T(3) syndrome of severe illness.
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Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet - NEJM - 0 views
www.nejm.org/...NEJMoa0708681
obesity overweight low carb diet low carbohydrate diet mediterranean diet weight weight loss DIRECT study
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Low Sex Hormone-Binding Globulin, Total Testosterone, and Symptomatic Androgen Deficien... - 0 views
press.endocrine.org/...jc.2005-1326
low testosterone T metabolic syndrome SHBG MetS men male hormone hormones
shared by Nathan Goodyear on 04 Feb 14
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Acute and short term chronic testost... [J Clin Endocrinol Metab. 2014] - PubMed - NCBI - 0 views
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Study finds that Testosterone regulates glucose metabolism, in part, through adiponectin production. Early state of low T will slow the use of fats as a source of fuel and this results in an increased energy balance and results in the increased adiponectin production to increase metabolism. Testosterone and adiponectin exist in an inverse relationship. This study does not mimic normal physiology. Men with low T are unhealthy with significant metabolic dysfunction. These young, "healthy" men were induced to a low T state--that is not a clear picture as the physiology of a "young healthy" man is quite different than that of one with low T. Testosterone conversion to DHT increases GLUT4 and thus glucose uptake--another mechanism of Testosterone's effect on glucose metabolism.
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Testosterone and the Cardiovascular System: A Comprehensive Review of the Clinical Lite... - 0 views
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Low endogenous bioavailable testosterone levels have been shown to be associated with higher rates of all‐cause and cardiovascular‐related mortality.39,41,46–47 Patients suffering from CAD,13–18 CHF,137 T2DM,25–26 and obesity27–28
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have all been shown to have lower levels of endogenous testosterone compared with those in healthy controls. In addition, the severity of CAD15,17,29–30 and CHF137 correlates with the degree of testosterone deficiency
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In patients with CHF, testosterone replacement therapy has been shown to significantly improve exercise tolerance while having no effect on LVEF
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testosterone therapy causes a shift in the skeletal muscle of CHF patients toward a higher concentration of type I muscle fibers
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Testosterone replacement therapy has also been shown to improve the homeostatic model of insulin resistance and hemoglobin A1c in diabetics26,68–69 and to lower the BMI in obese patients.
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Lower levels of endogenous testosterone have been associated with longer duration of the QTc interval
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negative correlation has been demonstrated between endogenous testosterone levels and IMT of the carotid arteries, abdominal aorta, and thoracic aorta
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These findings suggest that men with lower levels of endogenous testosterone may be at a higher risk of developing atherosclerosis.
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Current guidelines from the Endocrine Society make no recommendations on whether patients with heart disease should be screened for hypogonadism and do not recommend supplementing patients with heart disease to improve survival.
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The Massachusetts Male Aging Study also projects ≈481 000 new cases of hypogonadism annually in US men within the same age group
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since 1993 prescriptions for testosterone, regardless of the formulation, have increased nearly 500%
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Testosterone levels are lower in patients with chronic illnesses such as end‐stage renal disease, human immunodeficiency virus, chronic obstructive pulmonary disease, type 2 diabetes mellitus (T2DM), obesity, and several genetic conditions such as Klinefelter syndrome
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A growing body of evidence suggests that men with lower levels of endogenous testosterone are more prone to develop CAD during their lifetimes
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There are 2 major potential confounding factors that the older studies generally failed to account for. These factors are the subfraction of testosterone used to perform the analysis and the method used to account for subclinical CAD.
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The biologically inactive form of testosterone is tightly bound to SHBG and is therefore unable to bind to androgen receptors
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The biologically inactive fraction of testosterone comprises nearly 68% of the total testosterone in human serum
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The biologically active subfraction of testosterone, also referred to as bioavailable testosterone, is either loosely bound to albumin or circulates freely in the blood, the latter referred to as free testosterone
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It is estimated that ≈30% of total serum testosterone is bound to albumin, whereas the remaining 1% to 3% circulates as free testosterone
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it can be argued that using the biologically active form of testosterone to evaluate the association with CAD will produce the most reliable results
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English et al14 found statistically significant lower levels of bioavailable testosterone, free testosterone, and free androgen index in patients with catheterization‐proven CAD compared with controls with normal coronary arteries
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patients with catheterization‐proven CAD had statistically significant lower levels of bioavailable testosterone
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In conclusion, existing evidence suggests that men with CAD have lower levels of endogenous testosterone,13–18 and more specifically lower levels of bioavailable testosterone
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In a meta‐analysis of these 7 population‐based studies, Araujo et al41 showed a trend toward increased cardiovascular mortality associated with lower levels of total testosterone, but statistical significance was not achieved (RR, 1.25
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the authors showed that a decrease of 2.1 standard deviations in levels of total testosterone was associated with a 25% increase in the risk of cardiovascular mortality
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the relative risk of all‐cause mortality in men with lower levels of total testosterone was calculated to be 1.35
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higher risk of cardiovascular mortality is associated with lower levels of bioavailable testosterone
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Existing evidence seems to suggest that lower levels of endogenous testosterone are associated with higher rates of all‐cause mortality and cardiovascular mortality
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studies have shown that lower levels of endogenous bioavailable testosterone are associated with higher rates of all‐cause and cardiovascular mortality
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It may be possible that using bioavailable testosterone to perform mortality analysis will yield more accurate results because it prevents the biologically inactive subfraction of testosterone from playing a potential confounding role in the analysis
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In more recent studies, 3 randomized, placebo‐controlled trials demonstrated that administration of testosterone improves myocardial ischemia in men with CAD
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The improvement in myocardial ischemia was shown to occur in response to both acute and chronic testosterone therapy and seemed to be independent of whether an intravenous or transdermal formulation of testosterone was used.
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There is growing evidence from in vivo animal models and in vitro models that testosterone induces coronary vasodilation by modulating the activity of ion channels, such as potassium and calcium channels, on the surface of vascular smooth muscle cells
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Experimental studies suggest that the most likely mechanism of action for testosterone on vascular smooth muscle cells is via modulation of action of non‐ATP‐sensitive potassium ion channels, calcium‐activated potassium ion channels, voltage‐sensitive potassium ion channels, and finally L‐type calcium ion channels
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Corona et al confirmed those results by demonstrating that not only total testosterone levels are lower among diabetics, but also the levels of free testosterone and SHBG are lower in diabetic patients
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Laaksonen et al65 followed 702 Finnish men for 11 years and demonstrated that men in the lowest quartile of total testosterone, free testosterone, and SHBG were more likely to develop T2DM and metabolic syndrome.
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Vikan et al followed 1454 Swedish men for 11 years and discovered that men in the highest quartile of total testosterone were significantly less likely to develop T2DM
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authors demonstrated a statistically significant increase in the incidence of T2DM in subjects receiving gonadotropin‐releasing hormone antagonist therapy. In addition, a significant increase in the rate of myocardial infarction, stroke, sudden cardiac death, and development of cardiovascular disease was noted in patients receiving antiandrogen therapy.67
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Several authors have demonstrated that the administration of testosterone in diabetic men improves the homeostatic model of insulin resistance, hemoglobin A1c, and fasting plasma glucose
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Existing evidence strongly suggests that the levels of total and free testosterone are lower among diabetic patients compared with those in nondiabetics
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insulin seems to be acting as a stimulant for the hypothalamus to secret gonadotropin‐releasing hormone, which consequently results in increased testosterone production. It can be argued that decreased stimulation of the hypothalamus in diabetics secondary to insulin deficiency could result in hypogonadotropic hypogonadism
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This interaction may be a result of the promotion of lipolysis in abdominal adipose tissue by testosterone, which may in turn cause reduced abdominal adiposity. On the other hand, given that adipose tissue has a higher concentration of the enzyme aromatase, it could be that increased adipose tissue results in more testosterone being converted to estrogen, thereby causing hypogonadism. Third, increased abdominal obesity may cause reduced testosterone secretion by negatively affecting the hypothalamus‐pituitary‐testicular axis. Finally, testosterone may be the key factor in activating the enzyme 11‐hydroxysteroid dehydrogenase in adipose tissue, which transforms glucocorticoids into their inactive form.
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increasing age may alter the association between testosterone and CRP. Another possible explanation for the association between testosterone level and CRP is central obesity and waist circumference
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Bai et al have provided convincing evidence that testosterone might be able to shorten the QTc interval by augmenting the activity of slowly activating delayed rectifier potassium channels while simultaneously slowing the activity of L‐type calcium channels
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Intima‐media thickness (IMT) of the carotid artery is considered a marker for preclinical atherosclerosis
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Studies have shown that levels of endogenous testosterone are inversely associated with IMT of the carotid artery,126–128,32,129–130 as well as both the thoracic134 and the abdominal aorta
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1 study has demonstrated that lower levels of free testosterone are associated with accelerated progression of carotid artery IMT
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another study has reported that decreased levels of total and bioavailable testosterone are associated with progression of atherosclerosis in the abdominal aorta
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These findings suggest that normal physiologic testosterone levels may help to protect men from the development of atherosclerosis
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Czesla et al successfully demonstrated that the muscle specimens that were exposed to metenolone had a significant shift in their composition toward type I muscle fibers
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Type I muscle fibers, also known as slow‐twitch or oxidative fibers, are associated with enhanced strength and physical capability
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It has been shown that those with advanced CHF have a higher percentage of type II muscle fibers, based on muscle biopsy
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Studies have shown that men with CHF suffer from reduced levels of total and free testosterone.137 It has also been shown that reduced testosterone levels in men with CHF portends a poor prognosis and is associated with increased CHF mortality.138 Reduced testosterone has also been shown to correlate negatively with exercise capacity in CHF patients.
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Testosterone replacement therapy has been shown to significantly improve exercise capacity, without affecting LVEF
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the results of the 3 meta‐analyses seem to indicate that testosterone replacement therapy does not cause an increase in the rate of adverse cardiovascular events
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Data from 3 meta‐analyses seem to contradict the commonly held belief that testosterone administration may increase the risk of developing prostate cancer
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One meta‐analysis reported an increase in all prostate‐related adverse events with testosterone administration.146 However, when each prostate‐related event, including prostate cancer and a rise in PSA, was analyzed separately, no differences were observed between the testosterone group and the placebo group
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the existing data from the 3 meta‐analyses seem to indicate that testosterone replacement therapy does not increase the risk of adverse cardiovascular events
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the authors correctly point out the weaknesses of their study which include retrospective study design and lack of randomization, small sample size at extremes of follow‐up, lack of outcome validation by chart review and poor generalizability of the results given that only male veterans with CAD were included in this study
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the studies that failed to find an association between testosterone and CRP used an older population group
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low testosterone may influence the severity of CAD by adversely affecting the mediators of the inflammatory response such as high‐sensitivity C‐reactive protein, interleukin‐6, and tumor necrosis factor–α
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Good review of Testosterone and CHD. Low T is associated with increased all cause mortality and cardiovascular mortality, CAD, CHF, type II diabetes, obesity, increased IMT, increased severity of CAD and CHF. Testosterone replacement in men with low T has been shown to improve exercise tolerance in CHF, improve insulin resistance, improve HgbA1c and lower BMI in the obese.
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Correlates of low testosterone in men with chronic... [Andrology. 2014] - PubMed - NCBI - 0 views
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Low free testosterone is associated wit... [Geriatr Gerontol Int. 2014] - PubMed - NCBI - 0 views
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Hormonal and lifestyle determinants of appendicular skeletal muscle mass in men: the MI... - 0 views
ajcn.nutrition.org/...496.long
sarcopenia muscle free Testosterone muscle mass low T low Testosterone vitamin D physical activity smoking
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