In the follow up (F) of patients with DTC it is necessary to obtain high figures of serum TSH for determination of serum Tg and {sup 131}I scan (WBS). For this object, the method, for a long time, was to withdrawal thyroid hormone therapy (generally l-T4) that produced hypothyroidism with the inconvenient for the patients, 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 {sup 131}I. In 37 patients with DTC (G-1), aged 19-78 years, 34 with papillary DTC and 3 with follicular forms, 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 patients derived for A; G-1 B 36 patients for F or T with {sup 131}I. Six patients carried out 2 studies; 4 of them for A and for F and 2 realizes 2 times F. All patients treated with I-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 patients were injected i.v. with 200 mcg of TRH; at 30 minutes of the 3rd injection blood TSH determination; immediately 370 MBq of {sup 99m}T was administered and at 30 minutes a WBS was carried out. At 30 minutes of the 4th injection blood figures of TSH, Tg and Tg-ab were determined; immediately the activity of {sup 131}I indicated for each group was given to the patients; 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 patients that withdrawal-T4 for 4/5 weeks, were studied, aged 18-81 years, 31 females and 4 males; 32 with papillary and 3 follicular 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 7, 62 {+-} 52). The 2 tracers {sup 131}I and {sup 99m}Tc-Tc, produces show similar figures. In G-1A all p present thyroid remnants and elevated Tg. In G-1B, 7 patients showed positive WBS and Tg; 8 patients 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-2 A 71 {+-} 41 and G-2B, 63 {+-} 42. These findings indicate that the methods is adequate to shortened the time of withdrawal of I-T4 and reduce the signs/symptoms of hypothyroidism to an acceptable status. Also allow us to considered the use of {sup 99m}Tc as an indicator of existence of remnants, relapses or metastases and avoid blind use of therapeutic activities of {sup 131}I. (author) [Spanish] En el CDT es indispensable elevar los valores de TSH para efectuar Tg y barrido (RCT) con {sup 131}I, debiendose suspender la opoterapia (HT) durante 4/5 semanas con el consecuente hipotiroidismo (H) y los trastornos que conlleva. Nuestro objetivo fue incrementar en forma rapida TSH-E acortando el tiempo de abstinencia. Se efectuaron 43 estudios en 37 pacientes con CDT (G-1); de entre 19 y 78 anios, 34 con forma papilar y 3 folicular de CDT, 12 de sexo masculino y 25 femenino. Se consideraron 2 subgrupos, G-1A, 7 pacientes para ablacion (A); G-1B, 36 pacientes para seguimiento (S) y/o tratamiento (T) entre 6 meses y 5 anios poscirugia; 6 pacientes efectuaron dos estudios, 4 para A y S y 2 para 2 veces S. Como comparacion se revisaron 41 estudios en 35 p (G-2) que efectuaron suspension de opoterapia por 4/5 semanas, entre 18 y 81 anios; 28 de sexo femenino y 7 masculino; 32 papilares y 3 foliculares; 18 para A (G-2 A) y 21 para S, primer control (G-2B); 4 pacientes efectuaron 2 estudios, A y S. G-1A: entre 8/10 dias poscirugia se les administra TRH 200 …