It is not clear whether or not subclinical hypothyroidism (SH) is associated with an increased risk for cardiovascular disease.
We prospectively examined 43 women with SH and 49 healthy controls of similar age.
Fasting blood levels of thyrotropin, free thyroxin, antibodies to thyroid peroxidase and thyroglobulin, glucose, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and insulin were measured. Body mass index, waist and hip circumferences, blood pressure, homeostasis model assessment 2-insulin resistance index, and the presence of metabolic syndrome (MS) were also evaluated.
Mean systolic blood pressure was increased in SH patients versus controls (128.6 vs. 120.7 mm Hg; P = 0.04). Mean values of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and insulin were not different in patients with SH compared with controls. SH had significantly higher triglyceride levels (1.50 ± 0.65 mmol/L) and glucose levels (5.26 ± 0.63 mmol/L) compared with controls (1.27 ± 0.59, 5.05 ± 0.52; P = 0.04, P = 0.04, respectively). Although body mass index values were similar in both groups, patients had greater waist circumference than controls (90.7 ± 13 cm vs. 81.8 ± 10.6; P = 0.0007). The percentages of patients with SH having hypertension (34.1%), hypertriglyceridemia (37.2%), hyperglycemia (20.9%), and greater waist circumference (51.2%) were higher than the percentages in controls. Thus, the percentage of MS in patients (41.5%) was significantly higher than in controls (12.2%; P = 0.003). SH had significantly higher likelihood of cardiovascular risks (odds ratio, 6.26; 95% confidence interval, 1.6–4.49; P = 0.008 for MS).
We conclude that SH is associated with greater probability of MS. This may increase the risk of accelerated atherosclerosis and premature cardiovascular disease in these patients.