Endocrine Abstracts

Background: The impact of subclinical hyperthyroidism (sHT) on lipids concentration is still unclear. The aim of the study was to prospectively evaluate the changes in lipid profile in patients with sHT and following restoration of euthyroid state.

Patients and methods: The studied group consisted of 44 patients (37 females, 7 males), diagnosed with endogenous sHT in the course of either toxic multinodular goiter, diffused thyroid autonomy or autonomously functioning thyroid nodule. All patients were treated with radioiodine. We measured TSH, fT3, fT4, total cholesterol (TC), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), triglycerides (TG), and sex hormone binding globulin (SHBG) serum concentrations at admission, and at every check-up visit until the last visit, which was scheduled 6 months after the restoration of euthyroidism.

Results: The restoration of euthyroidism was associated with a statistically significant increase in LDL cholesterol from 114.3 to 121.9 mg/dl (P=0.018) and HDL cholesterol from 64.02 to 66.25 mg/dl (P=0.041). An increase in serum triglycerides from 95.2 to 102.6 mg/dl was also observed but it was not statistically significant (P=0.273). The total cholesterol serum concentration also increased after treatment (from 204.6 to 211.1 mg/dl), however the increase was statistically nonsignificant (P=0.11).

Conclusion: Treatment of sHT results in a statistically significant increase in LDL cholesterol and HDL cholesterol serum concentration. The rise in serum triglycerides and in total serum cholesterol did not reach statistical significance. Further studies assessing the impact of sHT treatment on lipid metabolism are still needed. It is still unclear how different treatment modalities and different causes of sHT impact lipid metabolism and whether the observed changes are clinically relevant in terms of cardiovascular risk.