甲状腺功能减退症(甲减)Hypothyroidism 中山大学附属第一医院内分泌科肖海鹏甲减的定义多种原因引起的甲状腺激素合成,分泌或生物学效应不足所致。以低代谢率，粘多糖在组织和皮肤堆积为特征，严重者表现为粘液性水肿（Myxedema ）及粘液性水肿性昏迷。甲减的分类根据病变部位分类原发性甲减(甲状腺性) 继发性甲减（垂体性）三发性甲减(下丘脑性) 受体性甲减（外周性）甲减的分类据病因分类药物性甲减[3]I 治疗后甲减手术后甲减特发性甲减甲减的分型呆小病（克丁病Cretinism ）幼年型甲减成年型甲减临床表现一般表现：疲劳、畏寒怕冷、出汗减少、皮肤干燥、萎黄虚肿、面容虚浮、声音嘶哑、毛发稀少干枯精神神经：乏力淡漠、少言嗜睡、反应迟钝心血管症状：心率减慢、心肌病、心包积液消化症状：纳差、便秘、腹胀其他症状：贫血、性欲减退、月经过多、泌乳甲状腺功能检查1 、TSH 增高，FT4 降低2 、131I 摄取率降低3 、TPOAb 、TgAb 阳性4 、TRH 兴奋试验Regulation of Thyroid Hormones 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 、伴肾上腺皮质功能减退者，先补皮质激素，以免诱发肾上腺危象4 、亚临床甲减替代治疗指征：高胆固醇TSH>10mu/L, 甲状腺自身抗体强阳性粘液水肿性昏迷的治疗1、补充甲状腺激素2 、保温、供氧、保持呼吸道通畅3 、氢化可的松的应用4 、补液，摄入水不宜过多5 、处理诱因或合并存在的疾病* Figure 15-11. (Left panel) Infant with severe, untreated congenital hypothyroidism diagnosed prior to the advent of newborn screening. (Right panel) Infant with congenital hypothyroidism identified through newborn screening. Note the striking difference in the severity of the clinical features. Figure 15-12. Ten year old female with severe 1° hypothyroidism due to primary myxedema before (A) and after (B) treatment. Presenting complaint was poor growth. Note the dull facies, relative obesity and immature bod proportions prior to treatment. At age 10 years she had not lost a single deciduous tooth. After treatment was initiated (indicated by the arrow in Panel C), she lost 6 teeth in 10 months and had striking catch up growth. Bone age was 5 years at a chronologic age of 10 years. TSH receptor blocking antibodies were negative.  Figure 9-3. (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. Puffiness 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 Müller's levator palpebral superious muscle and is the opposite of the lid retraction seen in 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 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 anemia is marked, the tongue may be pale, but more often it is red, in contrast to the pallid face. Figure 9-5. Flow-diagram for the biochemical diagnosis of hypothyroidism.  诊断Figure 4-3. Basic elements in the regulation of thyroid function. TRH is a necessary tonic stimulus to TSH synthesis and release. TRH synthesis is regulated directly by thyroid hormones. T4 is the predominant secretory product of the thyroid gland, with peripheral deiodination of T4 to T3 in the liver and kidney supplying roughly 80% of the circulating T3. Both circulating T3 and T4 directly inhibit TSH synthesis and release independently; T4 via its rapid conversion to T3. SRIH = somatostatin. *