Metabolic and cardiological changes in patients with subclinical hypothyroidism; evaluation of L-Thyroxine treatment

Objectives: Subclinical hypothyroidism is defined as a mild elevation in serum TSH (thyroid stimulating hormone) level while serum fT4 (free T4) and fT3 (free T3) levels are in reference range. Main problem with these patients is whether they will receive therapy or not. In many studies, positive effects of levothyroxine treatment on hypothyroidism symptoms, serum lipid levels and cardiac functions were shown. In this prospective clinical study, we aimed to evaluate the metabolic changes in the newly diagnosed patients with subclinical hypothyroidism and the effects of thyroxine treatment in these patients.Material and Methods: Fifty-three newly diagnosed patients with subclinical hypothyroidism who did not receive any therapy before were included in the study group. Randomly choosen 29 patients received therapy while the remaining 24 patients formed the control group and followed without any treatment. Patients were asked for symptoms and examined physically at the beginning of the study and at the end of sixth month. Thyroid function tests, lipid parameters, holter ECG and ECO at the beginning of the study and at the end of sixth month were compared between the 2 groups.Results: There were 40 (75.5%) female, 13 (24.5%) male patients; mean values of age and BMI were 44.02±13.9 years and 29.4±6.4 kg/m2. Mean TSH levels and mean fT3 levels were significantly decreased in the sixth month with respect to the begining in the patient with treatment when compared to the control group (p=0.005 and p=0.017 in the control group; p=0.00 and p=0.34 in the patient with treatment).In the beginning mean levels of serum LDL cholesterol were 108±34 mg/dl (normal), Lp(a): 87.6±284 mg/dl (high). Mean cholesterol level showed a significant increase in the control group in the sixth month (p=0.01), whereas minimal decrease in the patient with treatment (p=0.75). Serum Lp(a) level showed no difference during the six months time in the control group (p=0.52), whereas an insignificant decrease was seen in the patient with treatment (p=0.93). There was no significant change during six months period with respect to EF in both grups (p=0.43). Em showed a decrease in both groups and this decrease was more significant in the control group (p=0.013). In the control group, Em/Am ratio showed a significant decrease during this period (p=0005). At the beginning of the study, mean IVRZ levels of the patients were elevated (123±45.8msec). In the control group, IVRZ continued to increase in the six month period and this increase was statistically significant (p=0.012). On the other hand, in the patient with treatment, IVRZ level showed no significant difference in the six month (p=0.87)Conclusions: In this study, we found that the symptoms of clinical hypothyroidism mostly existed in patients with subclinical hypothyroidism, and clinical, cardiological and metabolic changes in these patients improved with levothyroxine therapy.