Endocrine Abstracts

Introduction: Graves’ disease (GD) is an autoimmune disorder causing hyperthyroidism. Variations of functional profile as well as type and titer of thyroid specific antibodies makes the control often difficult. One treatment option is adding levothyroxine to anti-thyroid drugs (ATDs), so-called block-replace therapy (BRT).

Aim: To study the BRT impact on lipid profile, thyroid function tests (TFTs) and TSH receptor antibodies (TRAb).

Materials & Methods: A prospective, observational study which enrolled 108 patients with active Graves’ disease, aged >18 years, with new diagnosis or relapse of GD who are receiving medical therapy. Pregnant women, patients treated with radiotherapy or surgery were excluded. We compare the data regarding TFTs, TRAb and lipid profile from diagnosis (visit 0) and during BRT (3 visits). Mean time between visit 1 and 2 was 137.2 days, respectively 105.3 days between visit 2 and 3. Data were analyzed with Microsoft Excel and Minitab v21. Data are presented as mean±SD.

Results: 90 women, aged 45.07±13.73 years and 18 men, aged 54±14.03 years were included. Out of 108 patients, only 95 had measured their lipid profile at diagnosis and 6 of them were on therapy with statin. The mean of total cholesterol at visit 0 was 161.64 mg/dl, significantly lower than during the BRT (194.51 mg/dl at visit 1; 194.61 mg/dl at visit 2 and 202.42 mg/dl at visit 3, P<0.001). The mean of low density lipoprotein (LDL-cholesterol) progressively raised from 92.29 mg/dl (N:<100 mg/dl) at diagnosis to 116.45 mg/dl at visit 1 and 122.01 mg/dl at visit 3. No impact was observed on the levels of triglycerides. For 102 patients, the mean of fT4 during BRT was 13.237 pmol/l (N:9-19) on a dose of 46.15±17.48 μg of levothyroxine daily. Mean dose of methimazole at diagnosis was 29.73±15.43 mg/day and 16.70±12.93 mg/day during BRT. Mean levels of T3 decreased from 364.53 ng/dl at diagnosis to 126.86 ng/dl (visit 1). Also, TRAb decreased from a mean of 17.07 UI/l (visit 0) to 8.71 UI/l (visit 3) (P=0.002).

Limitations: Small number of patients, limited time for observation, heterogeneous group.

Conclusion: Controlling hyperthyroidism in a block and replace regimen normalized the thyroid function, and worsened the lipid profile. This could be explained by the previously altered lipid profile before developing thyrotoxicosis, masked at the moment of diagnosis. A dynamic risk evaluation of lipid profile is suggested while treating thyrotoxicosis. Key words: hyperthyroidism, Graves’ disease, block-replace therapy, lipid profile.