A study Of The Relation Of Thyroid Functions To Components Of Metabolic Syndrome And It's Possible Relation To Cardiovascular Complications

Abstract

Metabolic syndrome constitutes a cluster of risk factors characterized by hypertension, atherogenic dyslipidemia, hyperglycemia, prothrombotic and proinflammatory conditions.

Metabolic syndrome affects approximately one quarter of the population in developed countries. Its presence is a major risk for development of both type 2 diabetes mellitus and atherosclerosis. The prevalence of cardiovascular disease is 2–3 times higher in individuals with metabolic syndrome than in age-matched controls.

Sub-clinical hypothyroidism and overt hypothyroidism are recognized risk factors for atherosclerotic cardiovascular disease, hyperlipidemia, low grade inflammation and hypercoagulability.

Subclinical hypothyroidism is a prevalent condition among adult population, however it is frequently overlooked. Thyroid functions affect metabolic syndrome parameters including HDL cholesterol, triglycerides, blood pressure and plasma glucose. On the other hand, the relation between metabolic syndrome and thyroid dysfunction is not clearly identified.

The aim of the study was tostudy relation of thyroid function to components of metabolic syndrome and to identify the cardiovascular risk involved in the association of thyroid dysfunction and metabolic syndrome. The study was conducted on 50 patients with metabolic syndrome according to the (NCEP – ATP III criteria) (NCEP, 2001) of both sexes (age range 18-55 years), recruited from the outpatient clinic and inpatient Endocrinology Unit , Internal Medicine Department, Ain Shams University Hospital. Patients were compared to 50 control subjects appropriately age and sex matched. Informed consent was obtained from all subjects. Patients were divided into three groups: • Group I: 25 patients with Metabolic syndrome and thyroid dysfunction, includingpatients with and without cardiovascular system affection. • Group II: 25 patients with Metabolic syndrome and normal thyroid function, includingpatients with and without cardiovascular system affection • Group III: 50 control subjects appropriately matched for age and sex.

Exclusion criteria involved patients with previous treatment with thyroid hormones or antithyroid medications,thyroid tumors, patients taking amiodarone, renal or hepatic diseases, severe debilitating illness, type 1 DM, and congenital heart diseases. Subjects were subjected to the following: -Detailed clinical history and thorough physical examination. -Anthropometric measurements: weight, height, waist and hip circumference and BMI (weight in Kg/ squared height in meter) (Speroff et al., 2005). -Laboratory tests including CBC,LFTs, RFTs, fasting blood glucose, two hour postprandial blood glucose, HbA1c, HOMA-IR test, total cholesterol level, serum HDL level, serum LDL level, serum triglycerides, serum uric acid, serum TSH, FT3, FT4 (measured by ELISA),thyroid antibodies (antithyroid peroxidase antibodies) as needed , as well as high sensitivity C reactive protein (HsCRP). -Radiological tests including thyroid ultrasound , and imaging as needed, as well as abdominal ultrasound to detect fatty liver. -Electrocardiography and echocardiography. In our study, we found non significant statistical difference between the studied groups regarding smoking, gender, weight, BMI and waist circumference. Regarding fatty liver, it was significantlyhigher in group I, 19 patients had fatty liver as opposed to 17 patients in group II. Regarding cardiovascular involvement, there was highly significant statistical difference between the patients groups (I and II). In group I, 4 patients had IHD (16%). In group II, there was no IHD Regarding blood pressure, it was significantly higher between each of the patients groups (I and II)than group III. Regarding serum lipid profile, total cholesterol and triglycerides, LDL levels were significantly higher and serum HDL level significantly lower in group I compared to group II and III. Regarding thyroid function, group I showed significantly higher serum TSH and significantly lowerfree T3 and free T4 levels compared to group II and III. In group I, 21 had subclinical hypothyroidism, 4 had overt hypothyroidism. Regarding the number of metabolic syndrome components, there was ahighly significant statistical difference between the studied groups. Patients with all 5 components of the syndrome were only found in group I. Regarding blood glucose, fasting and postprandial blood glucose, HbA1C and HOMA- IR , there was non significant statistical difference between patient groups I and II .They weresignificantly higher in each of patients groups (I and II)than group III. Regarding high sensitivity C reactive protein (HsCRP) it was significantly higher in group Ithan group II. The patients groups (I and II)had significantly higher CRP than group III. There was a significant positivecorrelation of HsCRP with waist circumference, TSH and with number of metabolic syndrome components. In group I, HsCRP showed a highly significant positive correlation with waist circumference, BMI and HOMA-IR.