Prasch F, Knosp S E, Steinbach R, Wogritsch S, Hurtl I, Greifeneder M, Holm C, Najemnik C, Dudczak R
Institut für Nuklearmedizin, Krankenhaus Lainz.
Acta Med Austriaca. 1999;26(1):32-6.
Elevated levels of free triiodothyronine (fT3) of 8.8 ng/dl (normal range 2.0 to 4.2) and free thyroxin (fT4) of 3.5 pg/ml (0.8 to 1.7) were found in the course of an examination of a 53-year old patient due to a planned hysterectomy. As thyrotropin (TSH) also was elevated with 5.8 mU/l (0.4 to 4.5), these findings corresponded to an inappropriate secretion of TSH (IST). Additional examinations revealed a blunted rise of TSH secretion after i.v. injection of 200 micrograms thyrotropin releasing hormone (TRH) as well as lacking suppression of TSH secretion after oral doses of 75 micrograms T3 during one week. alpha-TSH levels with 3.7 micrograms/l were elevated in comparison to a matched normal sample just as the molar ratio alpha-TSH/TSH with 6.95 and sex hormone-binding globulin (SHBG) with 175 nmol/l and showed an absence of inhibition in the T3 suppression test. These results were suggestive of neoplastic inappropriate secretion of TSH (nIST) due to a TSH-secreting pituitary adenoma. In concordance, the magnetic resonance imaging (MRI) showed a 1 cm tumor in the sella. The adenoma could also be visualized by 111In-octreotide and 123I-epidepride scintigraphies of the pituitary gland. After transsphenoidal resection, histological examination of the tumor resulted in the finding of a TSH-secreting adenoma. Postoperative TSH levels were not detectable, indicating the complete removal of the adenoma. Levels of fT3 and fT4 were slightly below normal with 1.9 pg/ml and 0.7 ng/dl, respectively. A control scintigraphy with 111In-octreotide following an equivocal MRI showed no uptake in the pituitary.
在对一名53岁因计划进行子宫切除术的患者进行检查过程中，发现其游离三碘甲状腺原氨酸（fT3）水平升高至8.8 ng/dl（正常范围2.0至4.2），游离甲状腺素（fT4）水平升高至3.5 pg/ml（0.8至1.7）。由于促甲状腺激素（TSH）也升高至5.8 mU/l（0.4至4.5），这些发现符合促甲状腺激素不适当分泌（IST）。进一步检查显示，静脉注射200微克促甲状腺激素释放激素（TRH）后，TSH分泌的上升减弱，且在口服75微克T3一周后，TSH分泌缺乏抑制。与匹配的正常样本相比，α-TSH水平为3.7微克/升升高，α-TSH/TSH摩尔比为6.95以及性激素结合球蛋白（SHBG）为175 nmol/l也升高，并且在T3抑制试验中显示缺乏抑制。这些结果提示由于分泌TSH的垂体腺瘤导致肿瘤性促甲状腺激素不适当分泌（nIST）。与此一致，磁共振成像（MRI）显示蝶鞍内有一个1厘米的肿瘤。通过垂体的111In-奥曲肽和123I-依匹必利闪烁扫描也可观察到腺瘤。经蝶窦切除术后，肿瘤的组织学检查结果为分泌TSH的腺瘤。术后TSH水平检测不到，表明腺瘤已完全切除。fT3和fT4水平分别略低于正常，为1.9 pg/ml和0.7 ng/dl。在MRI结果不明确后进行的111In-奥曲肽对照闪烁扫描显示垂体无摄取。
