Gurnell M, Rajanayagam O, Barbar I, Jones M K, Chatterjee V K
Department of Medicine, University of Cambridge, Addenbrooke's Hospital, United Kingdom.
Thyroid. 1998 Aug;8(8):679-82. doi: 10.1089/thy.1998.8.679.
We report pituitary enlargement after radioiodine ablation in a patient with elevated thyroid hormones and features of hyperthyroidism. Serum thyrotropin (TSH) levels were elevated despite normal circulating thyroid hormones, suggesting inappropriate TSH secretion associated either with a TSH secreting pituitary adenoma or resistance to thyroid hormone (RTH). Normal serum glycoprotein alpha-subunit levels and a preserved TSH response to thyrotropin-releasing hormone (TRH) favored RTH and this diagnosis was confirmed by showing the patient to be heterozygous for a missense mutation (R438H) in the thyroid hormone beta receptor (TRbeta) gene. Thyroxine replacement in supraphysiological doses were required to normalize TSH levels and resulted in regression of the pituitary enlargement, suggesting hyperplasia rather than coincident tumor. This case illustrates the need to avoid thyroid ablation in RTH patients and the importance of supraphysiological thyroxine replacement to prevent pituitary hyperplasia.
我们报告了一例甲状腺激素升高且有甲状腺功能亢进特征的患者在放射性碘消融后出现垂体增大的情况。尽管循环甲状腺激素水平正常，但血清促甲状腺激素（TSH）水平升高，提示存在与分泌TSH的垂体腺瘤或甲状腺激素抵抗（RTH）相关的不适当TSH分泌。血清糖蛋白α亚基水平正常以及TSH对促甲状腺激素释放激素（TRH）的反应保留支持RTH，通过显示该患者甲状腺激素β受体（TRβ）基因存在错义突变（R438H）的杂合性证实了这一诊断。需要超生理剂量的甲状腺素替代来使TSH水平正常化，并导致垂体增大消退，提示为增生而非巧合的肿瘤。该病例说明了避免对RTH患者进行甲状腺消融的必要性以及超生理剂量甲状腺素替代对预防垂体增生的重要性。
