The impact of achieving euthyroidism on plasma osteopontin levels and cardiovascular risk parameters among newly diagnosed hypothyroid patients

The Impact of Achieving Euthyroidism on Plasma Osteopontin Levels and Cardiovascular Risk Parameters among Newly Diagnosed Hypothyroid Patients Objective: Hypothyroidism is one of the most common endocrine disorders in population. Unfavorable effects of hypothyroidism on cardiovascular system are well-known. Bradycardia, systemic hypertension, narrowing of pulse pressure, systolic and diastolic heart disease, dyslipidemia, endothelial dysfunction, atherosclerosis and ischemic heart disease can be detected in such patients. High blood pressure, low-density lipoprotein cholesterol, C-reactive protein, homocysteine, plasminogen activator inhibitor-1 (PAI-1) and D-dimer are well-recognized atherogenic risk factors and are affected by hypothyroidism. Osteopontin (OPN) is a new marker of inflammation which is first isolated from bone and proposed to associate with immunity, inflammation and some malignancies. The purpose of this study is to investigate the use of plasma Osteopontin measurement as a predictor of cardiovascular risk in newly diagnosed hypothyroid patients. Material and Methods: Thirty-nine patients whose Thyroid Stimulating Hormone (TSH) levels are found to be above laboratory limits for the first time and 11 healthy euthyroid subjects were enrolled in the study. The patient group consisted of 4 (10.2 %) subclinical and 35 (89.8%) overt hypothyroid cases. Patients' TSH, free T4 (FT4), fibrinogen, C-reactive protein (CRP), fasting glucose, total cholesterol (T-chol), low-density lipoprotein cholesterol (LDL-chol), high-density lipoprotein cholesterol (HDL-chol), triglyceride, and OPN levels were measured at inclusion and on the third month after euthyroidism was sustained with levothyroxine treatment. Flow-mediated arterial dilatation measurement from brachial artery was performed twice simultaneously with laboratory analyses. Results: At inclusion, body mass index (BMI), T-chol, LDL-chol and triglyceride levels were statistically higher in hypothyroid group (p=0.01, p=0.01, p=0.02 and p=0.01 respectively). The FMD value was lower in same group (p=0.02). Fibrinogen, CRP and osteopontin levels were similar between groups (p> 0.05). Pre and post-treatment (after achieving euthyroidism) study parameters were compared in hypothyroid group. Statistically significant decrease in T-chol, LDL-chol, HDL-chol, and OPN levels (all p=0.000), and significant increase in FMD levels (p=0.000) were observed. There was no difference in other follow-up parameters. There was also no correlation between plasma osteopontin levels and FMD. Conclusion: Basal cardiovascular risk profile of our hypothyroid group is in accordance with literature. Lower FMD values at inclusion in patient group supports this finding, as well. Indifferent basal plasma OPN levels between both groups, makes it difficult to identify OPN as a cardiovascular risk factor for our study. However, besides amelioration in well-recognized cardiovascular risk factors with achieving euthyroidism, decrease in plasma OPN levels with accompanying increase in FMD was observed in hypothyroid group. This finding makes us think that OPN may be used as a marker for cardiovascular risk in hypothyroid patients. Our data needs to be proven with further studies.