内科学：35-甲状腺机能减退症

1、甲状腺机能减退症,由于多种病因引起的甲状腺素合成、分泌或生物效应不足所致的全身性低代谢综合症。,Regulation of Thyroid Hormones,病因与发病机理,原发性（甲状腺性）甲状腺功能减退症： 获得性： 甲状腺因自身免疫损伤, 炎症、手术、放疗、同位素或肿瘤广泛破坏 甲状腺素合成障碍：碘缺乏或碘过多、药物 先天性： 孕妇缺碘或口服过量抗甲状腺药 胎儿甲状腺素合成酶系统异常 先天性甲状腺不发育 异位甲状腺,病因与发病机理,继发性（中枢性）甲状腺功能减退症 TRH或TSH分泌减少 下丘脑、垂体的炎症、肿瘤、手术、放疗、 缺血坏死、损伤，特发性 甲状腺素抵抗综合症, TSH 或TH

2、不敏感综合征,临床表现,成年型甲减：怕冷、少汗、乏力、少言、动作缓慢、体重不减或增加 精神神经系统：记忆力下降、智力低下、反应迟钝、嗜睡、抑郁，严重者精神分裂 肌肉与关节：软弱无力、暂时性肌强直、痉挛、疼痛，偶有肌无力、肌萎缩，跟腱反射减弱 心血管系统：窦性心动过缓、心浊音界扩大、心音减弱，心包积液,临床表现,消化系统：厌食、腹胀、便秘，麻痹性肠梗阻或黏液水肿性巨结肠 内分泌系统：性欲减退、阳痿，月经过多、经期延长及不育 黏液性水肿：表情淡漠，面色苍白，眼睑浮肿，唇厚舌大，皮肤干燥、肿胀、粗糙脱屑，毛发稀少。部分出现指甲厚、脆、多裂纹。 黏液性水肿昏迷：嗜睡、低体温（ 350C）、呼吸缓慢、心

3、动过缓、血压下降、肌肉松弛、反射减退或消失，严重者昏迷、休克，心肾功能不全。,(A) The classic torpid facies of severe myxedema in a man. The face appears puffy, and the eyelids are edematous. The skin is thickened and dry. (B) The facies in pituitary myxedema is often characterized by skin of normal thickness, covered by fine wrinkles. P

4、uffiness is usually less than in primary myxedema. The eyelids are often edematous. The palpebral fissure may be narrwowed because of blepharoptosis, due to diminished tone of the sympathetic nervous fibers to Mllers levator palpebral superious muscle and is the opposite of the lid retraction seen i

5、n thyrotoxicosis. The modest measurable exophthalmos seen in some patients with myxedema is presumably related to accumulation of the same mucous edema in the orbit as is seen elsewhere. It is not progressive and carries no threat to vision, as in the ophthalmopathy of Graves disease. The tongue is

6、usually large, occasionally to the point of clumsiness. Sometimes a patient will complain of this problem. Sometimes it is smooth, as in pernicious anemia (of course, pernicious anemia may coexist). Patients do not usually complain of soreness of the tongue, as they may in pernicious anemia. When an

7、emia is marked, the tongue may be pale, but more often it is red, in contrast to the pallid face.,临床表现,呆小病：起病越早病情越重，体格智力发育迟缓，特殊面容。 幼年型甲减：介于成人型与呆小病之间。,(Left panel) Infant with severe, untreated congenital hypothyroidism diagnosed prior to the advent of newborn screening. (Right panel) Infant with con

8、genital hypothyroidism identified through newborn screening. Note the striking difference in the severity of the clinical features.,实验室检查与影象学检查,一般检查：贫血、血糖正常或偏低、血脂高 甲状腺功能检查：TSH、T3、T4、rT3 131I吸收降低,实验室检查与影象学检查,病变部位: TSH T3 T4 rT3 TRH 400 g ivdrip后TSH 原发性 继发性 无（垂体）/延迟（下丘脑） 亚临床 轻度 正常 正常或 正常或 影象学检查 病因检查：

9、病史、体征、特殊检查、TPOAb、 TGAb,诊断,临床表现 TT3、 TT4、 FT3 、FT4 、TSH TRH兴奋试验,鉴 别 诊 断,1、贫血 2、特发性水肿 3、心包积液 4、低T3综合征 5、蝶鞍增大,治 疗,原 则 甲状腺激素终生替代 支持疗法，补充营养及维生素B 病因治疗,治疗,替代治疗： 初始：左甲状腺素（L-T4）25-50g qd. 加量：每2-4周增加 12.5g qd- 25g qd. 维持：75-150 g qd （1.4-1.6g / kg标准体重） 疗效指标： TSH 恒定在正常范围内， 每6-12个月检查一次 个体化：年龄、伴发病、药物、妊娠 监测：体重、心功能、血脂、骨质疏松,治疗,对症治疗：贫血、高血脂 病因防治,治疗注意事项,1、小剂量开始，个体化，监测TSH、FT4 2、慎用镇静剂和麻醉剂，注意保暖和防治 感染 3、伴肾上腺皮