ECE2015 Guided Posters Thyroid – hypothyroidism (10 abstracts)
1Thyroid Research Group, IMEM, Cardiff University, Cardiff, UK; 2Department of Medical Biochemistry and Immunology, University Hospital of Wales, Wales, UK.
Introduction: The effects of mild subclinical hypothyroidism (SH; TSH <10 mU/l) on metabolic outcomes are unclear. This may relate to differences in aetiology, including thyroid autoimmunity or genetic factors such as TSH-receptor mutations (TSHR-M) and FOXE1 polyalanine tract length (FOXE1PTL) polymorphisms, which are associated with altered thyroid function. We hypothesised that the metabolic manifestations of SH may depend upon its aetiology.
Aims: i) To establish whether free T4, free T3, or TSH associate with metabolic parameters and blood pressure (BP) in SH. ii) To investigate whether SH aetiology has a differential effect on metabolic parameters and BP.
Methods: A total of 208 adults with primary untreated SH (TSH ≥5 mU/l) were recruited and underwent a medical/lifestyle history, resting BP and BMI measurement, genetic evaluation (for TSHR-M and FOXE1PTL status), thyroid function, anti-TPO antibody measurement, and metabolic assessments (HOMA-IR, full lipid profile). Associations were examined using stepwise multivariate regression analyses.
Results: TSH showed a small positive association with free T3 (R +0.6, P=0.01) and a negative association with free T4 (R −1.1, P<0.001) but no association with metabolic factors or BP. Free T3 showed a positive association with BP (systolic R +10, P<0.001 and diastolic R +3, P=0.02) and HOMA-IR (R +1.3, P=0.009). No significant metabolic associations were found for TSHR-M or TPO antibody positivity. The 14/14 FOXE1PTL (60% of cohort) was positively associated with free T3 compared to other genotypes (R +0.2, P=0.007) and negatively associated with BP (systolic R −6, P=0.006 and diastolic R −4, P=0.01).
Conclusions: Free T3 correlated positively with BP and HOMA-IR in this cohort, irrespective of SH aetiology. An unexpected association between FOXE1PTL polymorphisms and BP was revealed.
Disclosure: Society for Endocrinology grant.