The effect of recombinant human TSH on 123I thyroid uptake after intravenous iodide contrast agent

Recombinant human thyroid stimulating hormone (rhTSH) increases the thyroid radioactive iodine uptake (RAIU) in euthyroid and multinodular goiter patients. Furthermore, rhTSH is a well-known complementary tool in the management and treatment of differentiated thyroid cancer patients.

To evaluate the effect of rhTSH on RAIU in subjects without thyroid disease exposed to iodinated contrast agent during computed tomography (CT).

Nine euthyroid patients, seven female and two male, with ages ranging from 22 to 58 years, have signed a consent form approved by the hospital's Ethics Committee and had their TSH levels and RAIU evaluated in three moments: baseline (M1), 96 h after intravenous iodinated contrast agent (M2) and 24 h after intramuscular injection of 0.1 mg of rhTSH (M3). Each patient acted as his own control.

There was significant variation throughout the study of TSH (mean+/-SD): M1=2.39+/-0.92 microUI/ml; M2=2.54+/-1.28 microUI/ml; M3=7.54+/-2.96 microUI/ml (P=0.004) and of RAIU (mean+/-SD): M1: 8.76+/-2.4%; M2=6.54+/-1.77%; M3=18.75+/-8.24% (P=0.002). In both cases, there was a significant increment from M1 and M2 to M3.

It was shown that a single dose of 0.1 mg of rhTSH, given 96 h after the exposure to computed tomography iodinated contrast media, enhances the RAIU in nine euthyroid patients 4 h after 123I administration. These results indicate that rhTSH could be useful for avoiding delay in the treatment of patients with 131I.