title: Single, very low dose (0.03 mg) of recombinant human thyrotropin (rhTSH) effectively increases radioiodine uptake in the I-131 treatment of large nontoxic multinodular goiter.
abstract: BACKGROUND
  Radioiodine therapy (RIT) in patients with large nontoxic multinodular goiter (MNG) recently becomes more common method in comparison to surgery (especially in elderly patients and with contraindications because of severe chronic diseases other systems). Repeatedly low thyroid radioactive iodine uptake (RAIU) decreases effectiveness of RIT or makes it impossible. The recombinant human thyrotropin can increase RAIU and improve the results of RIT.
  
  
  OBJECTIVE
  was to assess the influence of a single very low dose (0.03 mg) of rhTSH on RAIU and thyroid function in euthyroid (MNG-EU) and subclinical hyperthyroid (MNG-SC) patients with a large multinodular goiter.
  
  
  METHODS
  40 patients (14 male, 26 female, age 57-80 yr) with large non-toxic MNG over 80 grams and with baseline RAIU < 40% were included into the double-blind randomized study and divided into two groups: rhTSH-group and control group. First group received the single intramuscular injection of 0.03 mg rhTSH and the second received placebo. The RAIU were measured 24 and 48 hours after the rhTSH and then all the patients were administered therapeutic doses of I-131. TSH and free thyroxine levels were measured at 1st and 2nd day after the injection of rhTSH and later, at 4 and 8 weeks after the RIT.
  
  
  RESULTS
  The mean RAIU increased significantly from 30.44 ± 7.4% to 77.22 ± 8.7% (p < 0.001). There were no statistically significant differences in RAIU between euthyroid (MNG-EU) and subclinically hyperthyroid (MNG-SC) patients. The peak of serum TSH was noticed 24 hours after rhTSH injection and in MNG-EU patients it has remained within normal range, similarly as fT4. In the MNG-SC group the administration of rhTSH resulted in a significant increase in the TSH values after 24 hours, whose mean level slightly exceeded the upper limit of the normal range with normalization at 48 hours. 8 weeks after the RIT, the TSH and fT4 levels did not exceed the normal range and did not differ in a statistically significant way.
  
  
  CONCLUSIONS
  Even the single very low dose of rhTSH increases the values of RAIU in significant way, in euthyroid and subclinically hyperthyroid patients. The administration of rhTSH is well-tolerated. Neoadjuvant administration of a low dose (0.03 mg) of rhTSH before I-131 seems to be an optimal method of management which may increase the effectiveness of RIT and decrease the exposure of the patients to absorbed doses of ionizing radiation.
authors: Nuclear Medicine Department, Medical University of Bialystok, Poland. m.mojsak@outlook.com.
authors: Małgorzata Natalia
authors: MN
authors: Mojsak
authors: Saeid
authors: S
authors: Abdelrazek
authors: Piotr
authors: P
authors: Szumowski
authors: Franciszek
authors: F
authors: Rogowski
authors: Monika
authors: M
authors: Sykała
authors: Jerzy
authors: J
authors: Kostecki
authors: Agnieszka
authors: A
authors: Kociura-Sawicka
authors: Dorota
authors: D
authors: Jurgilewicz
authors: Janusz
authors: J
authors: Myśliwiec
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006044:Goiter, Nodular / Q000150:complications / Q000378:metabolism* / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D006980:Hyperthyroidism / Q000150:complications; D007457:Iodine Radioisotopes / Q000378:metabolism* / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins / Q000494:pharmacology; D013972:Thyrotropin / Q000494:pharmacology*
chemical_list: D007457:Iodine Radioisotopes; D011994:Recombinant Proteins; D013972:Thyrotropin
keywords: I-131; large goiter; multinodular goiter; radioiodine therapy; radioiodine uptake; rhTSH