Abstract

DEGROSSI, O.J. et al. Rapid iterative stimulation (IS) of endogenous tsh (En-TSH) utilizing thyrotropin releasing hormone (TRH) in patients with differentiated thyroid carcinoma (DTC). Rev. argent. endocrinol. metab. [online]. 2007, vol.44, n.2, pp.67-77. ISSN 1851-3034.

In the follow up (F) of p with DTC it is necessary to obtain high figures of serum TSH for determination of serum Tg and ¹³¹I scan (WBS). For this object, he method, for a long time, was to withdrawal thyroid hormone therapy (generally l-T4) that produce hypothyroidism with the inconvenient for the p, dramatics in certain cases. Our objective was to increase TSH by IS to shortening time of L-T4 withdrawal for F, ablation (A) or treatment (T) with ¹³¹I. In 37 p. with DTC (G-1), aged 19-78 y., 34 with pap. DTC and 3 with foll. form, 25 females, 12 males, 43 studies were carried out; 6 p carried 2 studies. The group was divided in 2 sub-groups: G-1A,7 p derived for A; G-1 B 36 p. for F or T with ¹³¹I. Six p carried out 2 studies; 4 of them for A and for F and 2 realizes 2 times F. All p treated with l-T4 replaced this hormone for T3 during 3 weeks ,that was withdrawal the day before IS. In G-1A, between 8/10 days after surgery they begin IS. IS: At days 1, 3, 5 and 6, the p were injected i.v. with 200 mcg of TRH; at 30 minutes of the 3^rd injec. blood TSH determination ; immediately 370 MBq of ^99mT was administered and at 30 minutes a WBS was carried out. At 30 minutes of the 4^th injec. blood figures of TSH, Tg and Tg-ab were determined; immediately the activity of ¹³¹I indicated for each group was given to the p; in G-1A, at 8 days and in G1-B, at 48 hours WBS were carried out. As a control group (G-2) 41 studies in 35 DTC p. that withdrawal l-T4 for 4/5 weeks, were studied, aged 18-81 years, 31 females and 4 males; 32 with pap. and 3 folli.c form; 18 for A (G-2A) and 23 for F (G-2B); 6 p carried out 2 studies. One for A and the second as the first control. In G-1, TSH values obtained were 26-360 UI/L ( 83 ± 54. In G-1A : 137 ± 109 and in G-1B 62 ± 52). The 2 tracers ¹³¹I and ^99mTc-Tc, produce show similar figures. In G-1A all p present thyroid remnants and elevated Tg. In G-1B, 7 p showed positive WBS and Tg; 8 p present Tg positive and WBS negative and 21 WBS and Tg negative. In G-2, the TSH values obtained were 23-179 UI/L (63 ± 39 ); G-2A 71 ± 41 and G-2B 63 ± 42. These findings indicate that the methods is adequate to shortened the time of withdrawal of l-T4 and reduce the signs/symptoms of hypothyroidism to an acceptable status. Also allow us to considered the use of ^99mTc as an indicator of existence of remnants, relapses or metastases and avoid blind use of therapeutic activities of ¹³¹I.

Keywords : TRH-TSH; Differentiated thyroid carcinoma; Rapid stimulation.

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