Background: Subclinical hypothyroidism has been associated with hypercholesterolemia and atherosclerosis, so screening and treatment have been advocated to prevent cardiovascular disease. Objectives: clarification of cardiovascular risk of subclinical hypothyroidism.
Patients and Methods: 300 patients were admitted with coronary heart disease and data collected for demographic characteristics, baseline TSH and T4 levels., baseline cardiovascular risk factors such as diabetes, blood pressure, smoking, LDL and HDL-cholesterol serum levels, baseline used drug therapy . The 300 patients were divided into two groups; Gr.(1): 160 patients with coronary heart disease and subclinical hypothyroidism. Gr. (2) 140 patients with coronary heart disease and euthyroidism. Statistical correlation between coronary heart disease events and different TSHserum levels was followed.
Results: As regards to age, sex and FT4 serum levels, there were no statistical differences. Actually, we noticed that patients whatever with unstable angina (50%), revascularization (21.25%), or presented with acute myocardial infarction (15%), had TSH serum level 4.5 or greater and less than 20 mIU/L with normal serum levels of L-thyroxine, which undergo what is known as underactive thyroid or subclinical hypothyroidism.
Conclusion: subclinical hypothyroidism is associated with an increased risk of coronary heart disease especially in those with higher TSH levels and significantly elevated in adults with TSH levels of 10 mIU/L or greater. The results of our present study may help in refining a TSH threshold at which larger clinical benefits of thyroxine replacement would be expected.

Keyword:TSH-CHD-Atherosclerosis-Dyslipidemia-Controversy of TSH level.

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