title: Primary hypothyroidism in the community: Lower daily dosages of levothyroxine replacement therapy for Asian patients.
abstract: The goal of treatment in patients with primary hypothyroidism is to attain euthyroidism guided by the stipulated thyroid-stimulating hormone (TSH) levels range so as to minimize any potential long-term adverse effects. However, various factors may result in their Levothyroxine (T4) under and over-replacement.Our study aimed to evaluate the mean daily dose of L-T4 replacement for Asian patients with primary hypothyroidism. The secondary aims were to determine the proportion of those who were either over or under-replaced, and the factors associated with their thyroid function status and replacement adherence.Data collected using questionnaire survey from targeted patients managed in a typical public primary care center in Singapore: socio-demographic characteristics, clinical parameters, laboratory investigations, mean daily L-T4-replacement doses, and replacement regimens. The thyroid status of patients was classified based on thyroid function investigations.Complete data of 229 patients were analyzed. A total of 59.8% of patients had TSH within the normal range, 27.5% and 12.7% were under and over-replaced, respectively. About 60% of Asian patients with primary hypothyroidism achieved normal TSH status requiring average of 1.1 μg of daily L-T4/kgBW (kg body weight). Subjects who were over-replaced had a higher daily L-T4 dose/kgBW when compared to the euthyroid and the under replaced groups. Those with L-T4 over-replacement were largely due to excessive dosage. Patients who were younger, from lower socioeconomic strata, and higher BMI were more likely to be over or under-replaced.Majority of Asian patients with hypothyroidism required replacement of 1.1 μg of daily L-T4/kgBW. Their thyroid status was influenced by demographic and dosing factors.
authors.affiliation: Department of Research, SingHealth Polyclinics Duke NUS Medical School, Singapore Faculty of Medicine, University of New South Wales, Sydney, Australia Department of Endocrinology, Changi General Hospital, Singapore.
authors.forename: Ngiap Chuan
authors.initials: NC
authors.lastname: Tan
authors.forename: Rong Quan
authors.initials: RQ
authors.lastname: Chew
authors.forename: Yi Ling Eileen
authors.initials: YLE
authors.lastname: Koh
authors.forename: Reena Chandini
authors.initials: RC
authors.lastname: Subramanian
authors.forename: Usha
authors.initials: U
authors.lastname: Sankari
authors.forename: Meykkumar
authors.initials: M
authors.lastname: Meyappan
authors.forename: Li Wei
authors.initials: LW
authors.lastname: Cho
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D020249:Hormone Replacement Therapy / Q000379:methods*; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy* / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D012846:Singapore; D012959:Socioeconomic Factors; D013974:Thyroxine / Q000008:administration & dosage / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D013974:Thyroxine