testosterone

Japanese: テストステロン

(3) Testosterone (T)
The male gonadal hormone blood T levels gradually decrease with age, but in Japan, a decrease in free T levels has been confirmed (Figure 12-17-4) (Iwamoto et al., 2004). Late-onset hypogonadism (LOH) is a syndrome caused by a decrease in blood T levels. Its symptoms are diverse, including decreased libido and erectile function, cognitive ability, and orientation, fatigue, depression, sleep disorders, visceral obesity, and bone loss. In fact, in LOH patients, although not in all cases, various symptoms, including psychiatric symptoms, are improved by T administration. Recently, there have been many reports showing that a decrease in blood T levels in elderly men is associated with an increase in the mortality rate over the next 20 years, independent of various other risk factors, and that a higher blood T level within the physiological concentration range is actually more inhibitory (protective) against the onset and progression of lifestyle-related diseases such as arteriosclerosis, obesity, and diabetes. The degree of carotid intima-media thickening, an index of visceral fat accumulation and arteriosclerosis in men, is inversely correlated with blood T levels. When endogenous blood T levels in young healthy adults are lowered by administration of GnRH analogues, an increase in body fat percentage and a decrease in resting energy expenditure are observed, suggesting that a decrease in T leads to an increase in body fat. This is also evident from the fact that antiandrogen drug treatment in prostate cancer patients leads to an increase in body fat, insulin resistance, and diabetes at a high rate. In addition, in terms of bone mass, the prevalence of osteoporosis increases in men over 60 years of age as a result of a decrease in total T levels. On the other hand, the importance of blood estrogen concentration in maintaining bone mass in men is well known from analyses of male patients with aromatase deficiency, and T acts to maintain bone mass through its direct effect on bones as well as its conversion to estrogen in peripheral tissues. T supplementation is mainly carried out by intramuscular injection of depot preparations, as there has been little progress in the development of effective oral agents. There have been reports of improvements in obesity, insulin resistance, glucose metabolism, and arteriosclerosis risk markers in middle-aged and elderly men through T supplementation, as well as increases in lumbar bone mineral density, but these results are still limited to small numbers of people, and remain a challenge for the future (Yanagisawa et al., 2010). [Yanagisawa Toshihiko]
■ References <br /> Iwamoto, A. et al.: Establishing reference values for total and free testosterone in Japanese adult males. Journal of the Japanese Society of Urology, 95: 751-760, 2004.
Roth GS, et al: Biomarkers of caloric restriction may predict longevity in humans. Science, 297: 811, 2002.
Toshihiko Yanase and Kunitaka Murase: Hormone replacement therapy for anti-aging - GH, DHEA, testosterone. Clinical Research, 87: 515-520, 2010.

Figure 12-17-4
Free testosterone reference value ">

Figure 12-17-4

Source : Internal Medicine, 10th Edition About Internal Medicine, 10th Edition Information

Japanese:

（3）テストステロン（testosterone：T）
　男性の性腺ホルモンである血中T値は加齢に伴い漸減するが，わが国では遊離T値の低下が確認されている（図12-17-4）（岩本ら， 2004）．加齢男性性腺機能低下症候群（late-onset hypogonadism：LOH）は血中Tの低下によりもたらされる症候群である．その症状は，性欲，勃起能の低下，認知力，見当識の低下，疲労感，抑うつ，睡眠障害，内臓脂型肥満，骨量減少など多岐にわたる．実際，LOH患者では全例ではないにしてもT投与により精神症状も含めた諸症状の回復を認める．最近，高齢男性の血中T濃度の低下はほかの種々の危険因子とは独立してその後の20年間の死亡率の増加に関連するとの成績や，生理的濃度の範囲の血中Tは，むしろ高いほど，動脈硬化や肥満，糖尿病といった生活習慣病の発症や進展には抑制的（防御的）であるとの成績が数多く報告されている．男性の内臓脂肪蓄積や動脈硬化の指標である頸動脈内膜中膜肥厚の程度は血中T値と逆相関する．若年健康成人の内因性血中T値をGnRHアナログの投与によって低下させた場合には，体脂肪率の増加と安静時エネルギー消費量の低下が認められることから，Tの低下が体脂肪増加をもたらすと考えられる．このことは，前立腺癌患者における抗アンドロゲン薬治療により体脂肪の増加，インスリン抵抗性，糖尿病を高率に発症してくることからもわかる．また骨量に関しても60歳以上の男性では総T値の低下により骨粗鬆症の有病率が増加する．一方，男性における骨量維持における血中エストロゲン濃度の重要性は，アロマターゼ欠損症の男性患者の解析などからよく知られており，Tは，骨への直接効果に加えて，末梢組織でのエストロゲンへの転換を介して骨量維持に作用する．なお，T補充は，効果的な経口剤の開発が進んでいない現状から，デポー製剤の筋注が主体となっている．中高年男性へのＴ補充により肥満，インスリン抵抗性，糖代謝，動脈硬化リスクマーカーなどの改善を認めたとする報告や腰椎骨密度の増加も報告されているが，いまだ少人数の研究成績に限られており，今後の課題である（柳瀬ら， 2010）．［柳瀬敏彦］
■文献
岩本晃明，他：日本人成人男子の総テストステロン，遊離テストステロンの基準値の設定．日泌尿会誌，95: 751-760，2004．
Roth GS, et al: Biomarkers of caloric restriction may predict longevity in humans. Science, 297: 811, 2002.
柳瀬敏彦，村瀨邦崇：アンチエイジングとしてのホルモン補充療法− GH, DHEA, テストステロン−.　臨床と研究，87: 515-520, 2010．

図12-17-4
遊離テストステロン基準値">

図12-17-4

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