甲状腺功能减退症的诊治争议
甲状腺功能减退症的诊治争议
Hypothyroidism is a common disorder characterized by an inadequate cellular thyroid effect to meet the needs of the tissues. Typical symptoms of hypothyroidism include the following: fatigue, weight gain, depression, cold extremities, muscle aches, headaches, decreased libido, weakness, cold intolerance, water retention, premenstrual syndrome (PMS), and dry skin. Low thyroid causes or contributes to the symptoms of many conditions, but the deficiency is often missed by standard thyroid testing. This is frequently the case with such conditions as depression, hypercholesterolemia (high cholesterol), menstrual irregularities, infertility, PMS, chronic fatigue syndrome (CFS), fibromyalgia, fibrocystic breasts, polycystic ovary syndrome (PCOS), hyperhomocysteinuria (high homocystine), atherosclerosis, hypertension, obesity, diabetes, and insulin resistance.
The TSH test is generally considered the most sensitive marker of peripheral tissue levels of thyroid. We believe this view, however, is incorrect. Most endocrinologists and other physicians erroneously assume that, except for unique situations, a normal TSH is a clear indication that the person’s tissue thyroid levels are adequate (symptoms are not due to low thyroid). But a more thorough understanding of the physiology of hypothalamic-pituitary-thyroid axis and tissue regulation of thyroid hormones exposes as clearly erroneous the widely held belief that the TSH is an accurate marker of the body’s overall thyroid status.
TSH 与垂体 T3 水平呈负相关；但有生理压力 (1-32)、抑郁症 (33-38)、胰岛素抵抗和糖尿病 (28,39,116,117)、衰老 (30,40-49)、卡路里剥夺 (节食)(27, 50-57)、炎症(5-8,22,108,109-111)、PMS (58,59)、慢性疲劳综合征和纤维肌痛 (60,61)、肥胖 (112,113,114) 和许多其他疾病 (1-32)，垂体 T3 水平升高通常与细胞和组织 T3 水平降低，身体其他部位 T3 水平升高（1-62）（见垂体图）。垂体在解剖学和生理学上都是独一无二的，对炎症、慢性卡路里减少（节食）和生理压力的反应不同于身体中的其他组织 (1-20,50-52,62,63)。在生理压力或节食期间，T4 向 T3 的转化减少，全身组织中抗甲状腺逆向 T3 的形成增加，垂体除外，垂体是增加垂体 T3 水平的局部机制 (1-63) .
三端双向可控硅/四端双向可控硅
Physiologic stress, depression, emotional stress and chronic dieting also result in the abnormal stimulation other mechanisms that reduce cellular thyroid activity but is not detected by standard blood tests. This abnormal metabolic pathway converts T4 into a substance called tetraiodothyroacetic acid (Tetrac) and T3 into a substance called triiodothyroacetic acid (Triac) (128-132). The levels of Tetrac and Triac increase two to twelve-fold with dieting or physiologic stress (129-132). Both these substances are selectively taken up by the pituitary and suppress TSH production but have no effect in the rest of the body (128,129,134-137). Everts et al found that Triac is twice as potent as T3 at suppressing TSH secretion and 20 times more potent than T4 at suppressing TSH secretion (137). Thus, with physiologic or emotional stress, chronic dieting, depression and inflammation, the pituitary T3 levels do not correlate with T3 levels in the rest of the body–the TSH does not rise despite significant cellular hypothyroidism. This is another reason that the TSH is not a reliable or sensitive marker of an individual’s true thyroid status if such common conditions are present and is another reason that a TSH cannot be relied upon as an accurate marker for tissue thyroid status.
