Subclinical hypothyroidism may be associated with elevated high-sensitive c-reactive protein (low grade inflammation) and fasting hyperinsulinemia

The association between coronary heart disease and subclinical hypothyroidism (SCH) is unclear. We aimed to determine hs-CRP concentrations in patients with SCH. Seventy-seven patients (age 34.6 +/- 13.7 yr) with SCH (TSH >4.2 muIU/ml and serum free thyroxine level between 0.932-1.71 ng/dL), and 80 control subjects (age 33.9 +/- 13.3 yr) were studied. Thyroid hormones, C-reactive protein, insulin, glucose, total, HDL, LDL and VLDL-cholesterol levels and HOMA-IR index were also determined. TSH levels of SCH group were higher than control (7.4 +/- 2.9 and 1.55 +/- 0.78 muIU/ml, respectively, p=0.0001). However, FT4 levels were lower than control subjects (1.18 +/- 0.22 ng/dL and 1.38 +/- 0.26, respectively, p=0.001). Serum hs-CRP levels of subjects with SCH were higher than control subjects (4.2 +/- 0.8 mg/l and 1.05 +/- 0.3 mg/l respectively, p=0.0001). Insulin levels of SCH group were higher than control (8.5 +/- 4.3 muU/ml and 7.1 +/- 3.1 muU/ml respectively, p<0.02) but, Homa-IR levels of the two groups were not different. Mean total and LDL-cholesterol levels of SCH group were higher than control (p=0.01 and p<0.02). We also found a positive correlation between hs-CRP levels and insulin (r=0.362, p=0.002 in men, r=0.358, p=0.0001 in women), TSH (r=0.611, p=0.0001 in men, r=0.411 p=0.0001 in women), and prolactin (r=0.340, p=0.01 in men r=0.553, p=0.0001 in women). Conclusions: Patients with SCH, irrespective of gender, have higher serum hs-CRP, insulin, total and LDL-cholesterol levels than healthy subjects. 2-High hs-CRP level, and thereby low grade inflammation may be associated with fasting hyperinsulinemia before insulin resistance becomes evident in patients with SCH.