Ridgway E C, Cooper D S, Walker H, Rodbard D, Maloof F
J Clin Endocrinol Metab. 1981 Dec;53(6):1238-42. doi: 10.1210/jcem-53-6-1238.
Twenty patients with serum levels of T4 and T3 within the normal range but with elevated serum concentrations of TSH were evaluated before and after treatment with L-T4. This therapy increased serum T4 (5.5 +/- 1.1 to 8.8 +/- 1.8 microgram/dl) and T3 (116 +/- 20 to 137 +/- 28 ng/dl) levels. Cardiac systolic time intervals (STI) were significantly (P less than 0.01) reduced by this therapy. The preejection period (123 +/- 18 to 114 +/- 14 msec; n = 12), the change in preejection period (+17 +/- 17 to +6 +/- 15 msec; n = 12), the ratio of preejection period to left ventricular ejection time (0.412 +/- 0.068 to 0.357 +/- 0.063 msec; n = 12), and the interval from the Q wave of the electrocardiogram to the pulse wave arrival time at the brachial artery (224 +/- 10 to 200 +/- 13 msec; n = 10) were consistently reduced. Cardiac STI were significantly correlated with serum TSH and T4 levels, but not with serum T3 levels. Normalization of serum TSH levels was associated with changes in QKd measurements even in those patients with minimal elevations in serum TSH. These studies demonstrate that patients having the combination of elevated TSH but T4 and T3 levels in the normal range have alterations in STI which can be changed significantly by L-T4 in doses which normalize TSH secretion. These data suggest that such patients have a mild form of primary hypothyroidism.
对20例血清T4和T3水平在正常范围内但血清促甲状腺激素（TSH）浓度升高的患者在接受L-T4治疗前后进行了评估。该治疗使血清T4水平（从5.5±1.1微克/分升降至8.8±1.8微克/分升）和T3水平（从116±20纳克/分升降至137±28纳克/分升）升高。该治疗使心脏收缩时间间期（STI）显著缩短（P<0.01）。射血前期（从123±18毫秒降至114±14毫秒；n = 12）、射血前期的变化（从+17±17毫秒降至+6±15毫秒；n = 12）、射血前期与左心室射血时间的比值（从0.412±0.068降至0.357±0.063毫秒；n = 12）以及心电图Q波至肱动脉脉搏波到达时间的间期（从224±10毫秒降至200±13毫秒；n = 10）均持续缩短。心脏STI与血清TSH和T4水平显著相关，但与血清T3水平无关。即使在血清TSH轻度升高的患者中，血清TSH水平的正常化也与QKd测量值的变化相关。这些研究表明，TSH升高但T4和T3水平在正常范围内的患者存在STI改变，而L-T4以使TSH分泌正常化的剂量可显著改变这些改变。这些数据提示此类患者患有轻度原发性甲状腺功能减退症。
