Journal of Thyroid Disorders & Therapy
Open Access

Abstract

Metabolic and Cardiovascular Aspects of Subclinical Hypothyroidism: Effects of L-Thyroxin Replacement Therapy

Mehtap Evran, Murat Sert, Tamer Tetiker and Murat Çaylı

Background: Subclinical hypothyroidism (SH) is a common clinical issue, presented with high serum TSH and normal T4, T3 levels. Various clinical and metabolic derangements were reported related to SH. L-T4-replacement is a challenge in daily practice. We investigated the efficacy of L-T4-replacement on certain metabolic and cardiovascular parameters in subjects with SH.

Methods: Fifty-three (40 female; 13 male) subjects were included. Of the 53 subjects, 29 were randomly given L-T4 replacement, 24 were followed as control group through 6-months. Before L-T4 replacement (basal) and at the end of the study; symptoms, physical examination, serum metabolic parameters, Holter ECG and trans-thoracic echocardiography were performed. Two groups were compared.

Results: Mean age of the patients was 44.02 ± 13.9; body mass index 29.4 ± 6.4 kg/m2. In the T4-replacement group, there was a significant difference between serum TSH and FT3 levels compared to the basal measurements (p = 0.005 and p = 0.017). LDL-cholesterol levels of the replacement group were not changed significantly, but of the control group significantly increased (p=0.01). Mean ejection fraction (EF) did not show significant change at both basal and 6-month. Peak transmitral early diastolic flow speed (E) decreased in the control group (p = 0.013). Peak transmitral late diastolic flow speeds (Em/Am) of the controls were found to be decreased compared to the basal ratio (p = 0.005). Isovolumetric relaxation times (IVRT) of both groups were prolonged at the time of basal measurements (123 ± 45.8 msc). Long IVRT persisted in the control group through the study (p=0.012).

Conclusion: Symptoms of hypothyroidism are common in subjects with SH, and L-T4 replacement can improve the Cand metabolic derangements.