Studies also show a consistent negative correlation of testosterone with blood pressure (Barrett-Connor and Khaw 1988; Khaw and Barrett-Connor 1988; Svartberg, von Muhlen, Schirmer et al 2004). Data specific to the ageing male population suggests that this relationship is particularly powerful for systolic hypertension (Fogari et al 2005). Interventional trials have not found a significant effect of testosterone replacement on blood pressure (Kapoor et al 2006).
^ Butenandt A, Hanisch G (1935). "Umwandlung des Dehydroandrosterons in Androstendiol und Testosterone; ein Weg zur Darstellung des Testosterons aus Cholestrin" [About Testosterone. Conversion of Dehydro-androsterons into androstendiol and testosterone; a way for the structure assignment of testosterone from cholesterol]. Hoppe-Seyler's Z Physiol Chem (in German). 237 (2): 89–97. doi:10.1515/bchm2.1935.237.1-3.89.
^ Jump up to: a b Sapienza P, Zingales L, Maestripieri D (September 2009). "Gender differences in financial risk aversion and career choices are affected by testosterone". Proceedings of the National Academy of Sciences of the United States of America. 106 (36): 15268–73. Bibcode:2009PNAS..10615268S. doi:10.1073/pnas.0907352106. PMC 2741240. PMID 19706398.
Supplement nutrients when levels are low. Low levels of zinc and vitamin D may contribute to low testosterone levels in teenage boys, so increasing these nutrients through diet or dietary supplements can also help boost your testosterone. If your zinc and/or vitamin D levels are already normal, though, use caution before further increasing those levels with supplements.

Testosterone functions within the brain. There are several lines of evidence for this: there are androgen receptors within the brain; testosterone is converted to both dihydrotestosterone (DHT) and estradiol by the actions of 5-α-reductase and aromatase respectively in the brain; steroid hormones promote neuronal cell growth and survival (Azad et al 2003). Testosterone enhances cerebral perfusion in hypogonadal men and that perfusion takes place specifically in Brodman areas 8 and 24, regions of the brain that are concerned with: strategic planning, higher motor action, cognitive behaviors, emotional behavior, generalized emotional reaction, wakefulness and memory (Greenlee 2000; Azad et al 2003). Studies of cognition demonstrate that older men with higher levels of free testosterone index (a surrogate measure of bioavailable testosterone) have better scores in tests of: visual memory, verbal memory, visuospatial functions and visuomotor scanning. Hypogonadal men have lower scores in tests of memory, visuospatial function, with a faster decline in visual memory (Moffat et al 2002). In a very small, short term placebo-controlled study hypogonadal men with Alzheimer’s Disease (AD) treated with testosterone demonstrated a modest improvement in a cognition assessment score in AD (Tan and Pu 2003).

Sprinting has been shown numerous times that it has positive effects on testosterone levels. One 2011 study (ref 84) looked at weightlifters who performed 4x35m sprints twice a week. In contrast to the control group (who continued lifting but did not sprint), it was found that “After the 4-week training program, total testosterone and the total testosterone/cortisol ratio increased significantly in the (sprinters) EXP group”.

A: Testosterone production declines naturally with age. Low testosterone, or testosterone deficiency (TD), may result from disease or damage to the hypothalamus, pituitary gland, or testicles that inhibits hormone secretion and testosterone production. Treatment involves hormone replacement therapy. The method of delivery is determined by age and duration of deficiency. Oral testosterone, Testred (methyltestosterone), is associated with liver toxicity and liver tumors and so is prescribed sparingly. Transdermal delivery with a testosterone patch is becoming the most common method of treatment for testosterone deficiency in adults. A patch is worn, either on the scrotum or elsewhere on the body, and testosterone is released through the skin at controlled intervals. Patches are typically worn for 12 or 24 hours and can be worn during exercise, bathing, and strenuous activity. Two transdermal patches that are available are Androderm (nonscrotal) and Testoderm (scrotal). The Androderm patch is applied to the abdomen, lower back, thigh, or upper arm and should be applied at the same time every evening between 8 p.m. and midnight. If the patch falls off before noon, replace it with a fresh patch until it is time to reapply a new patch that evening. If the patch falls off after noon, do not replace it until you reapply a new patch that evening. The most common side effects associated with transdermal patch therapy include itching, discomfort, and irritation at the site of application. Some men may experience fluid retention, acne, and temporary abnormal breast development (gynecosmastia). AndroGel and Testim are transdermal gels that are applied once daily to the clean dry skin of the upper arms or abdomen. When used properly, these gels deliver testosterone for 24 hours. The gel must be allowed to dry on the skin before dressing and must be applied at least 6 hours before showering or swimming. Gels cannot be applied to the genitals. AndroGel is available in a metered-dose pump, which allows physicians to adjust the dosage of the medication. Side effects of transdermal gels include adverse reactions at the site of application, acne, headache, and hair loss (alopecia). For more specific information on treatments for low testosterone, consult with your doctor or pharmacist for guidance based on current health condition. Kimberly Hotz, PharmD
^ Mehta PH, Jones AC, Josephs RA (Jun 2008). "The social endocrinology of dominance: basal testosterone predicts cortisol changes and behavior following victory and defeat" (PDF). Journal of Personality and Social Psychology. 94 (6): 1078–93. CiteSeerX doi:10.1037/0022-3514.94.6.1078. PMID 18505319. Archived from the original (PDF) on April 19, 2009.
Some of the effects of testosterone treatment are well recognised and it seems clear that testosterone treatment for aging hypogonadal men can be expected to increase lean body mass, decrease visceral fat mass, increase bone mineral density and decrease total cholesterol. Beneficial effects have been seen in many trials on other parameters such as glycemic control in diabetes, erectile dysfunction, cardiovascular risk factors, angina, mood and cognition. These potentially important effects require confirmation in larger clinical trials. Indeed, it is apparent that longer duration randomized controlled trials of testosterone treatment in large numbers of men are needed to confirm the effects of testosterone on many aspects of aging male health including cardiovascular health, psychiatric health, prostate cancer and functional capacity. In the absence of such studies, it is necessary to balance risk and benefit on the best available data. At the present time the data supports the treatment of hypogonadal men with testosterone to normalize testosterone levels and improve symptoms. Most men with hypogonadism do not have a contraindication to treatment, but it is important to monitor for adverse consequences including prostate complications and polycythemia.
A number of epidemiological studies have found that bone mineral density in the aging male population is positively associated with endogenous androgen levels (Murphy et al 1993; Ongphiphadhanakul et al 1995; Rucker et al 2004). Testosterone levels in young men have been shown to correlate with bone size, indicating a role in determination of peak bone mass and protection from future osteoporosis (Lorentzon et al 2005). Male hypogonadism has been shown to be a risk factor for hip fracture (Jackson et al 1992) and a recent study showed a high prevalence of hypogonadism in a group of male patients with average age 75 years presenting with minimal trauma fractures compared to stroke victims who acted as controls (Leifke et al 2005). Estrogen is a well known determinant of bone density in women and some investigators have found serum estrogen to be a strong determinant of male bone density (Khosla et al 1998; Khosla et al 2001). Serum estrogen was also found to correlate better than testosterone with peak bone mass (Khosla et al 2001) but this is in contradiction of a more recent study showing a negative correlation of estrogen with peak bone size (Lorentzon et al 2005). Men with aromatase deficiency (Carani et al 1997) or defunctioning estrogen receptor mutations (Smith et al 1994) have been found to have abnormally low bone density despite normal or high testosterone levels which further emphasizes the important influence of estrogen on male bone density.

Nearly 1 out of every 4 men over age 50 experience the pain of losing the ability to perform sexually as a result of erectile dysfunction (ED). Common causes of ED are atherosclerosis, diabetes, prescription drug use (namely high blood pressure, depression, and allergy drugs), and—you guessed it—low testosterone. Supplements that may help include the following:
Millions of American men use a prescription testosterone gel or injection to restore normal levels of the manly hormone. The ongoing pharmaceutical marketing blitz promises that treating "low T" this way can make men feel more alert, energetic, mentally sharp, and sexually functional. However, legitimate safety concerns linger. For example, some older men on testosterone could face higher cardiac risks.