Crinò A, Borrelli P, Salvatori R, Cortelazzi D, Roncoroni R, Beck-Peccoz P
Dipartimento di Endocrinologia, Ospedale Pediatrico Bambino Gesù, IRCCS, Roma, Italy.
J Endocrinol Invest. 1992 Feb;15(2):113-20. doi: 10.1007/BF03348675.
In the present study, we report the uncommon case of a 9.6-yr-old girl with circulating anti-T3 autoantibodies (T3-Ab) and hyperthyroidism due to inappropriate secretion of TSH (IST). The diagnosis of IST was based on the findings of normal TSH levels (2.4 mU/L) in the presence of high free T4 (28.2 pmol/L) and free T3 (FT3) levels, as measured by direct measurement methods based on "one-step" analog tracer (28.0 pmol/L) and "two-step" Lisophase (13.3 pmol/L) techniques. The discrepancy between the two measurements suggested a methodological interference due to T3-Ab in "one-step" technique, being the "two-step" methodology unaffected by the presence of such autoantibodies. T3-Ab were documented by high nonspecific binding of serum to labeled T3 (38.0% vs 4.3 +/- 2.1% in controls). The clinical picture of hyperthyroidism, the qualitatively normal TSH responses to TRH and T3 suppression tests, the normal pituitary imaging and the values of some parameters of peripheral thyroid hormone action compatible with hyperthyroidism indicated that the patient was affected by pituitary resistance to thyroid hormones (PRTH). Chronic treatment with dopaminergic agent bromocriptine (7.5 mg/day) did not cause TSH secretion to be suppressed, while the administration of thyroid hormone analog TRIAC (1.4 mg/day) inhibited TSH release (from 2.4 to 0.2 mU/L). As a consequence, circulating thyroid hormone levels normalized and euthyroidism was restored. During TRIAC administration, FT3 levels, measured by "one-step" analog tracer technique, gave spuriously high values due to the methodological interference of T3-Ab (15.2 vs 4.3 pmol/L as measured by "two-step" Lisophase technique).(ABSTRACT TRUNCATED AT 250 WORDS)
在本研究中，我们报告了一例罕见病例，一名9.6岁女孩存在循环抗T3自身抗体（T3-Ab）且因促甲状腺激素（TSH）分泌不当（IST）导致甲状腺功能亢进。IST的诊断基于以下发现：采用基于“一步法”类似物示踪剂（28.0 pmol/L）和“两步法”Lisophase（13.3 pmol/L）技术的直接测量方法，在游离T4水平较高（28.2 pmol/L）和游离T3（FT3）水平较高时，TSH水平正常（2.4 mU/L）。两种测量方法之间的差异表明“一步法”技术中T3-Ab造成了方法学干扰，而“两步法”不受此类自身抗体存在的影响。通过血清与标记T3的高非特异性结合记录到T3-Ab（38.0%，而对照组为4.3±2.1%）。甲状腺功能亢进的临床表现、TSH对促甲状腺激素释放激素（TRH）和T3抑制试验的定性正常反应、垂体影像学正常以及一些与甲状腺功能亢进相符的外周甲状腺激素作用参数值表明该患者患有垂体性甲状腺激素抵抗（PRTH）。用多巴胺能药物溴隐亭（7.5 mg/天）进行长期治疗未导致TSH分泌受到抑制，而给予甲状腺激素类似物三碘甲状腺乙酸（TRIAC，1.4 mg/天）可抑制TSH释放（从2.4降至0.2 mU/L）。结果，循环甲状腺激素水平恢复正常，甲状腺功能恢复正常。在给予TRIAC期间，采用“一步法”类似物示踪剂技术测量FT3水平时，由于T3-Ab的方法学干扰得出了假性高值（“两步法”Lisophase技术测量值为4.3 pmol/L，而此处为15.2 pmol/L）。（摘要截断于250字）
