Influence of discontinuance of methimazole and propylthiouracil on 24 h radioactive iodine uptake in normal rats / 中华核医学与分子影像杂志

ABSTRACT

Objective To investigate the influence of discontinuance of methimazole (MMI) and propylthiouracil (PTU) on 24 h radioactive iodine uptake(RAIU) in normal rats.Methods A total of 66 female SD rats were randomly divided into 3 groups by simple random sampling method.MMI group (30 rats) received MMI with a dose of 0.6 mg · ml-1 · d-1 orally for 2 weeks,PTU group (30 rats) received PTU with a dose of 6 mg · ml-1 · d-1 orally for 2 weeks.At 1,3,5,7 and 9 d after MMI or PTU was discontinued,6 rats were sacrificed to measure 24 h RAIU respectively.The control group (6 rats) received normal saline with a dose of 1 ml/d orally for 2 weeks,and then they were sacrificed to measure 24 h RAIU too.Data were analyzed with two-sample t test or t'test.Results Thyroid 24 h RAIU in normal rats was (14.6±4.3) ％.The 24 h RAIU on 1,3,5,7 and 9 d was (4.6±0.7) ％,(24.2±7.2) ％,(13.1 ±2.9) ％,(14.1±2.6) ％,(16.1 ±3.7)％ respectively after MMI withdrawal.The 24 h RAIU was significantly lower than that in control group at day 1 (t'=5.55,P＜0.01),higher at day 3 (t=-2.83,P＜0.05),and returned to the normal level at day 5,7,9 (t =0.68,0.24,-0.67,all P＞0.05).The 24 h RAIU on 1,3,5,7 and 9 d was (1.9±0.8)％,(3.3±1.2)％,(7.7±2.4)％,(29.0±4.0)％,(17.1±4.8)％ respectively after PTU withdrawal.It was lower than that in control group (t=7.01,6.10,3.40,all P＜0.05) at day 1,3,5,and higher at day 7 (t=-5.97,P＜0.01).The 24 h RAIU of 9 d showed no difference when compared with that in control group (t=-0.95,P＞0.05).Conclusions MMI and PTU can inhibit the iodine uptake of thyroid,the 24 h RAIU returns to normal level at day 5 after withdrawal of MMI and at day 9 after withdrawal of PTU in euthyroid rats.