Department of Endocrinology and Medicine, Aalborg Hospital, Aarhus University Hospital, 9000 Aalborg, Denmark.
Eur J Endocrinol. 2011 Mar;164(3):317-23. doi: 10.1530/EJE-10-1021. Epub 2011 Jan 5.
Subclinical hypothyroidism (SCH) is a common condition that is often observed without therapy. However, no evidence-based recommendation exists with regards to how patients with untreated SCH should be monitored. Monitoring involves regular assessment of symptoms and signs of hypothyroidism (HYPO) and biochemical tests of thyroid function. An important question when repeated tests of thyroid function are performed is how large a difference in test results is needed to be confident that the change is real and not just due to chance variation. Recent data show that the least significant difference between two tests in SCH is 40% for TSH and 15% for free thyroxine and free triiodothyronine, with 90% confidence. Furthermore, monitoring has to be based on biochemical function testing because serial evaluation of symptoms and signs related to HYPO is rather insensitive in detecting worsening of thyroid insufficiency. When the presence of thyroid peroxidase auto-antibodies (TPO-Ab) in serum has been demonstrated, repeated measurements do not add much useful information in the monitoring of individual subclinical hypothyroid patients, as levels of TPO-Ab vary in parallel with TSH in these patients. Lastly, we discuss how differences in the monitoring procedure influence the diagnostic outcome, and we suggest a follow-up approach for untreated subclinical hypothyroid patients.
亚临床甲状腺功能减退症（SCH）是一种常见的病症，通常无需治疗即可观察到。然而，目前尚无循证医学推荐意见，针对未经治疗的 SCH 患者应如何进行监测。监测包括定期评估甲状腺功能减退症（HYPO）的症状和体征，以及甲状腺功能的生化检查。当进行重复的甲状腺功能检查时，一个重要的问题是需要多大的测试结果差异才能有信心认为这种变化是真实的，而不是仅仅由于随机变异所致。最近的数据表明，SCH 中两次测试之间 TSH 的最小有意义差异为 40%，游离甲状腺素和游离三碘甲状腺原氨酸的最小有意义差异为 15%，置信区间为 90%。此外，监测必须基于生化功能测试，因为连续评估与 HYPO 相关的症状和体征在检测甲状腺功能减退症恶化方面相当不敏感。当已经证明血清中存在甲状腺过氧化物酶自身抗体（TPO-Ab）时，在监测个别亚临床甲状腺功能减退症患者时，重复测量并没有增加太多有用的信息，因为在这些患者中，TPO-Ab 水平与 TSH 平行变化。最后，我们讨论了监测程序的差异如何影响诊断结果，并为未经治疗的亚临床甲状腺功能减退症患者提出了一种随访方法。
