Subclinical hypothyroidism and its association with cardiovascular risk factors.
Subclinical hypothyroidism (SH) represents the mildest form of thyroid hormone deficiency and may be associated with adverse consequences [Subclinical hypothyroidism was defined as a TSH level > 4.0 mIU/L and a normal free thyroxine level 0.6-1.8 ng/dL]. The identification of patients with subclinical hypothyroidism having an increased cardiovascular risk (CVR) is important. The aim of the study was to evaluate atherosclerotic risk factors in patients with subclinical hypothyroidism. Forty patients with subclinical hypothyroidism and forty healthy euthyroid controls, age and gender matched were included in the study. Serum total triiodothyronine (T3), thyroxine (T4), TSH, free T3 (FT3) and free T4 (FT4) were measured by enzyme linked immunosorbent assay (ELISA). Atherosclerotic risk factors measured were high sensitivity-CRP (hs-CRP), Lipoprotein (a) [Lp (a)] and lipid parameters. Lipid parameters (triglycerides, total cholesterol and high density lipoprotein cholesterol) were analysed by enzymatic colorimetric, endpoint method whereas the hs-CRP and Lp (a) were measured by quantitative latex turbidimetric method. Patients with subclinical hypothyroidism had significantly higher levels of serum hs-CRP, Lp (a), total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) when compared to same parameters of controls. Further, a significant positive correlation was observed between TSH and hs-CRP, Lp (a), LDL-C and TC in subjects with subclinical hypothyroidism. However, TG levels showed no significant correlation with TSH levels. We concluded that the SH patients presented increased concentration of some CVR factors. The potential benefits of diagnosis and treatment of subclinical hypothyroidism may have possible advantages firstly by preventing the progression to overt hypothyroidism and secondly decrease the risk of death from cardiovascular disease (CVD) by starting appropriate therapy to improve lipid parameters. Further research is needed on subclinical hypothyroidism and the associated atherosclerotic risk factors.