Endocrine Abstracts

Introduction: The BSPED UK thyrotoxicosis study has been running for 10 years. The primary objective is to assess biochemical control on block and replace (BR) and dose titration (DT) regimens. The final patient was recruited towards the end of 2011 and study will finish in 2015. We would like to describe the baseline characteristics of study patients and the initial response to anti-thyroid drug therapy (ATD).

Methods: We focused on patient age, sex, BMI and the initial change in levels of TSH and free thyroxine (FT₄) following initiation of anti-thyroid drug. We also examined the time taken for FT₄ and TSH to normalise according to local reference values.

Results: 81 patients have been recruited (41BR, 40 DT). 77% were female, median age at presentation was 13 years (range 3–16 years) and 83% were aged 10–15 years. The median BMI SDS was 0.08 with a range from −1.92 to 2.4. The median baseline FT₄ was 48 (range 13.5–150 pmol/l). The percentage of FT₄ values in the range <25, 25–50, 51–75, 76–100 and >100 pmol/l was 6, 47, 15, 23 and 6% respectively. In 98% cases TSH was suppressed at diagnosis. The average starting dose of ATD (Carbimazole) was 0.65 mg/kg per day and FT₄ normalised in 60% of cases within 4weeks and in 95% patients within 16weeks. Only 12% achieved normal TSH values within 4weeks and 45% by 16weeks. There was no relationship between baseline thyroid function and time taken for FT₄ to normalise.

Conclusions: UK patients with thyrotoxicosis are not thin at presentation. Parents can be informed that FT₄ will be within the normal range or close to normal range within 4 weeks if a dose of Carbimazole between 0.5 and 0.75 mg/kg is administered. TSH levels cannot be used to guide therapy in this early phase of treatment.