八、预后
亚临床甲亢患者可以进展为显性甲亢，部分患者甲功可自行恢复正常，血清TSH被抑制程度是预测亚临床甲亢进展为显性甲亢的最佳指标。
轻度亚临床甲亢进展为显性甲亢的自然病程目前尚不清楚，在TEARS研究中，对2 024名患者进行随访，7年后大约0.7%的患者发展为显性甲亢。2项前瞻性研究经过长期随访证实，25%～50%的轻度亚临床甲亢患者恢复正常。而每年有5%～8%的重度亚临床甲亢的患者进展为显性甲亢，TSH在0.1mIU/L以下时与显性甲亢之间存在相关性。
目前还不确定亚临床甲亢的潜在病因是否是进展为显性甲亢的预测因素。大多数患Graves病的亚临床甲亢患者最终结局发展为显性甲亢或者TSH恢复正常，一直维持原状的可能性较小。有一项研究评估了病因为Graves病的亚临床甲亢患者5年的自然病程，发现对于65岁以下的患者而言，通常在发病后的第一年是发展为显性甲亢的发病高峰，应激和怀孕可以加速这一进程[16]。由自身免疫因素导致的亚临床甲亢，如果TSH水平自发地恢复正常，通常说明患者合并短暂的甲状腺炎或者轻度Graves病。在多结节性甲状腺肿患者，如果患有亚临床甲亢，这种状态会持续很长时间，特别是在碘缺乏地区。而在非碘缺乏地区，每4～5年大约有10%的患者由非毒性结节性甲状腺肿进展为毒性结节性甲状腺肿。此外，在碘缺乏区，病因为毒性结节性甲状腺肿的重度亚临床甲亢患者通常会进展为显性甲亢，尤其是在补碘治疗或者应用含碘造影剂（碘源性甲亢）之后。
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