Effects of routine and intermittent protocols, on rising TSH level and clinical manifestations of hypothyroidism in 60 patients with differentiated thyroid carcinoma, preparing for whole body scan wit

Introduction: it is favorable to obtain an optimal level of TSH with a minimum of clinical manifestations of hypothyroidism in patients with differentiated thyroid carcinoma, preparing for whole body scan with I131. Methods: We compared two protocol: routine and intermittent. .In routine protocol , 4-6 weeks after surgery , levothyroxin discontinued and liothyronin (50 μg/day) prescribed for two weeks , then liothyronin discontinued for 2 weeks and TSH measured at the end of this time.In intermittent protocol , levothyroxin prescribed 100 μg every other day and after 30 days levothyroxin discontinued and TSH was measured. If TSH was 30 μu/ml or more scan performed and if TSH was lower than 30 μu/ml, we asked for patients to comeback one week later and TSH was measured again. Results:.Mean of age was 40.5 years. Fifty patients were female and 10 cases were male. Fifty-three patients (88.3%) had papillary and 7 cases(11.7%) had follicular carcinoma. Twenty-two patients performed intermittent protocol and 38 patients were on routine protocol.There was no significant difference in mean of age (p=0.145) ,female to male ratio (p=0.9) and type of carcinoma between two groups. (p=0.95)There was no significant difference in pulse rate per minute(p=0.128), skin dryness (p=0.7),constipation(p=0.73),paresthesia(p=0.2) ,puffiness(p=0.15),change in weight(p=0.157), systolic (p=0.05) and diasolic(p=0.119)blood pressures. Abnormal reflexes were not seen in any patients in two groups.In routine protocol 14 days after discontinuation of levothyroxin TSH reached to 53.7 μu/ml . In intermittent protocol mean of TSH 30 days after every other day use of levothyroxine was 16.2 μu/ml and 10.5 days after complete discontinuation of levothyroxine was 46.8 μu/ml . there was no significant difference in TSH level between two groups at the end of two protocol. (p=0.08) Conclusion: Severity of hypothyroid manifestations in intermittent protocol was not different with routine protocol.Exposure to high levels of TSH and its outcomes is less in intermittent protocol . It is reasonable to check TSH level before whole body scan in any of two methods to be sure of reaching to optimal level of TSH.