Does a mild form of subclinical hypothyroidism need treatment?

Abstract

Background: Overt hypothyroidisms warrants L-T4 treatment, but treatment in subclinical hypothyroidism (ScH), especially in mild form of ScH (TSH between 4,2-10mU/l and normal free thyroxine) is unknown.

Objectives: To compare the presence of risk factors for atherosclerosis in patients with mild form of ScH to euthyroid subjects.

Methods: Prospectively 67 consecutive patients with newly diagnosed ScH, and 30 healthy subjects were recruited from the outpatient department of University clinic of endocrinology in Skopje, R. of N. Macedonia. Measurement of thyroid hormones, thyroid antibodies, blood pressure, lipids, and carotid intima media thickness (CIMT) were performed in all patients.

Results: Mean TSH value in ScH group was 8.71± 1,9 mU/l. TSH value above 7mU/l was associated and positively correlated with symptoms of hypothyroidism. Prevalence of hypertension in ScH group was higher than the control group (35.4% vs. 13.3%, P = 0,03), with a 3.5 times higher risk for hypertension (OR= 3,5 95%CI 1,1 – 11,4). In patients with mild form of SCH statistical significant difference in percentages of patients with arterial hypertension, hypertriglyceridemia, and values of total cholesterol/HDL-C and LDL/HDL above upper reference value were found (33.9 vs. 13.3%, 33.9 vs. 10%, 26.5 vs. 6.9%, 30.6% vs. 10.3%, respectively P < 0.05). Mean CIMT was statistically significantly higher in ScH patients than the control group (0.61 ± 0.1 vs. 0,56 ± 0,1 mm, P=0.03), but not different between the mild form of ScH and control group (P=0.08). Positive thyroid antibodies in the ScH group have no statistically significant influence on the CIMT.

Conclusions: In a small study, mild form of ScH was associated with higher risk for atherosclerosis, so these patients may benefit with L-T4 treatment.

Key words. Subclinical hypothyroidism, risks factors, atherosclerosis, carotid intima media thickness