Paraoxinase-1 Activity in Patients with Subclinical Hypothyroidism: A link to Atherosclerosis

Objective: To investigate paraoxinase-1 (PON-1) activity in subclinical hypothyroidism (SCH) patients in comparison with acute coronary syndrome (ACS) patients and to determine the prevalence of SCH among patients with ACS.

Background: Paraoxonase1 (PON1) is an antioxidant enzyme that plays an important role in lipoprotein metabolism; it is an indicator of the risk of atherosclerosis and coronary artery disease development. Thyroid hormones are associated with both the oxidant-antioxidant balance and lipoprotein metabolism; SCH and its correlation with the atherosclerotic cardiovascular diseases is a subject of debate.

Subjects and Methods: This study included 95 subjects from Menou????ia University Hospital after exclusion of all known cardiovascular risk factors, classi????ied into :Group I (control group) (n=15); Group II (ACS subjects) (n=46), Group III (SCH subject) (n=20) and Group IV (subjects with both ACS and SCH) (n=14).Thorough history taking; complete physical examination, thyroid function tests, lipid pro????ile, PON-1 activity, electrocardiogram (ECG) and echocardiographic examination of the heart were done.

Results: PON-1 activity was highly signi????icant lower in group II and IV than group III than control; there are a signi????icant negative correlation between PON-1 activity and thyroid stimulating hormone and a highly signi????icant positive correlation with FT4.In addition the severity of dyslipidemia and the prevalence of diastolic dysfunction in group III were comparable to that in group II and the prevalence of SCH among ACS patients is 23.3%.

Conclusion: This study suggests that SCH is an independent risk factor for ACS, and the prevalence of SCH among patient with ACS was 23.3%.

Keywords: Atherosclerosis, Paraoxinase-1, Subclinical Hypothyroidism.