Guimaraes V, DeGroot L J
Department of Medicine, University of Chicago, Illinois 60637, USA.
Thyroid. 1996 Apr;6(2):69-73. doi: 10.1089/thy.1996.6.69.
Patients who have undergone thyroidectomy for thyroid carcinoma are frequently subjected to periods of induced severe hypothyroidism in preparation for 131I whole body scanning and measurement of serum TG. These two tests are crucial in evaluating the patient's clinical status and determining administration of 131I or other necessary treatment. Severe hypothyroidism produces fatigue, weight gain, depression, inability to carry out usual activities, and occasionally significant illness. We compared the efficacy of inducing moderate hypothyroidism by cutting replacement therapy in half, to a standard method. In the standard preparation, patients substituted triiodothyronine for thyroxine replacement over a 3-week period, and then omitted hormone therapy for 3 weeks. For the subsequent scan, 6 to 12 months later, the thyroxine dosage was cut in half. TSH levels were assessed 4 weeks later, and if adequately elevated, whole body scanning was conducted at the end of the fifth week. Pulse, weight, clinical symptoms, thyroid hormone levels, and some clinical chemistries were evaluated prior to each scan, and some of the tests were also carried out during the interval between scans. Moderate hypothyroidism induced by the half-dose protocol induced TSH elevations above the target level (25-30 microU/mL) at 5 weeks in most patients. Typically TSH of 15 microU/mL in the previous week predicted adequate elevation of TSH at the time of scan. Half dose therapy can be prolonged, if necessary, especially in patients who begin with extreme suppression of TSH, or if a higher TSH is desired. Pulse, weight gain, and cholesterol were significantly different in the two protocols, and the patient's subjective evaluation of hypothyroid symptoms was significantly reduced. Reduction of thyroxine replacement dosage to half the usual amount, in patients with thyroid cancer, allows after 5 weeks in most patients sufficient elevation of TSH for whole body scanning and measurement of TG levels. This simple and economical procedure drastically reduces symptomatology of hypothyroidism and makes this key procedure much more tolerable to patients.
因甲状腺癌接受甲状腺切除术的患者，在准备进行131I全身扫描和血清TG测定时，经常会经历一段诱导性严重甲状腺功能减退期。这两项检查对于评估患者的临床状况以及确定131I或其他必要治疗的给药至关重要。严重甲状腺功能减退会导致疲劳、体重增加、抑郁、无法进行日常活动，偶尔还会引发严重疾病。我们将把替代疗法减半以诱导中度甲状腺功能减退的效果与标准方法进行了比较。在标准准备方案中，患者在3周内用三碘甲状腺原氨酸替代甲状腺素替代治疗，然后停用激素治疗3周。在随后6至12个月进行扫描时，将甲状腺素剂量减半。4周后评估TSH水平，如果充分升高，则在第五周结束时进行全身扫描。在每次扫描前评估脉搏、体重、临床症状、甲状腺激素水平和一些临床化学指标，并且在扫描间隔期间也进行一些检查。半剂量方案诱导的中度甲状腺功能减退在大多数患者中于5周时使TSH升高至目标水平（25 - 30微单位/毫升）以上。通常前一周TSH为15微单位/毫升可预测扫描时TSH会充分升高。如有必要，半剂量治疗可以延长，特别是对于开始时TSH极度受抑制的患者，或者如果需要更高的TSH水平。两种方案在脉搏、体重增加和胆固醇方面有显著差异，并且患者对甲状腺功能减退症状的主观评估显著降低。对于甲状腺癌患者，将甲状腺素替代剂量减至通常剂量的一半，在大多数患者中5周后可使TSH充分升高以进行全身扫描和TG水平测定。这种简单且经济的方法极大地减轻了甲状腺功能减退的症状，使这个关键程序对患者更易于耐受。
