European Journal of Cardiovascular Medicine

Thyroid conditions are among the most common endocrine disorders globally, just as they do in India [1]. According to data from the third National Health and Nutrition Examination Survey (NHANES III), the general population's prevalence of hypothyroidism was 4.6%. Hypothyroidism is caused by insufficient thyroid hormone secretion. Subclinical hypothyroidism occurs when free thyroid hormones are normal and TSH is increased to make up for decreased thyroid output. TSH levels continue to grow while T4 levels decrease as thyroid disease progresses. At this point, the patient is considered to have overt or clinical hypothyroidism, the TSH is typically more than 10 mU/l, and symptoms start to show [2]. A range of conditions known as hypothyroidism are characterized by abnormal thyroid function tests, which may or may not be linked to clinical symptoms. Thyroid hormone production rate irregularities are the root cause of most thyroid disorders. While hypothyroidism is brought on by insufficient production, hyperthyroidism is characterized by hyperactive tissue inside the thyroid gland, which leads to overproduction and an excess of circulating free thyroid hormones: thyroxin (T4), triiodothyronine (T3), or both [3]. Heat sensitivity, tremor, palpitations, anxiety, weight loss despite normal or increased hunger, increased frequency of bowel movements, and shortness of breath are common symptoms of hyperthyroidism [4].

Fatigue, weight gain, difficulty enduring cold, joint and muscle discomfort, dry skin or dry, thinning hair, heavy or irregular menstruation cycles or fertility issues, decreased heart rate, and depression are common clinical manifestations of hypothyroidism [5].

The scientific community has discussed hypothyroid patients' increased risk of coronary artery disease because of alterations in their lipoprotein profiles that have atherogenic effects [6]. HDL-C is decreased by hypothyroidism, but total and LDL cholesterol levels are decreased by hyperthyroidism due to increased cholesterol excretion and rapid low density lipoprotein (LDL) turnover [7].

Thyroid hormones have a major effect on chylomicron clearance and triglyceride turnover, and they also influence hepatic lipogenesis in both hyperthyroidism and hypothyroidism. Thyroid hormones reduce the production of hepatic total cholesterol and very low-density lipoproteins (VLDL) by increasing the oxidation of nascent fatty acids and decreasing re-esterification. People with hypothyroidism had higher hepatic VLDL secretion [8]. Hypothyroidism results in a larger ratio of low-density lipoprotein (LDL) to high-density lipoprotein (HDL), while hyperthyroidism results in a lower ratio [9].

Aim: The purpose of this research to determine the connection between lipid levels and aberrant thyroid functioning

This cross-sectional study was conducted in a tertiary care Indian hospital. The study sample comprised of 102 participants attending out-patient and in- patient departments during the study period.

The participant pool was divided into three groups:

Hypothyroid group, hyperthyroid group and euthyroid group (34 participants in each group)

Inclusion Criteria:

• Patient’s ≥ 18 years of age with both genders
• Patients diagnosed with hypothyroidism, Hyperthyroid or euthyroid
• Patients with no history of thyroxine and hypolipidemic drugs
• Patients who provide written informed consent for the study

Exclusion Criteria:

• Patient’s less than18 years of age
• Patients having diabetes mellitus, pregnancy, hypercortisolism or pituitary diseases
• History of drugs including; thyroxine, hypolipidemic, oral contraceptives, androgens, steroids, and immunosuppressant
• Patients who not provides written informed consent for the study

In the present study, 102 patients with thyroid disorders were recruited. Among patient’s majority of them (39.2%) were 41- 50 years age group, with female predominance (62.7%). Most of them (59.8%) were residing at urban area and 48% belong to middle socio-economic class. 38.2% patients were obese (Table I).

Table 1: Socio-demographic characteristics of study participants

Results of lipid assays (Table.2) mean serum levels of TC, TG VLDL, LDL cholesterol and LDL/HDL ratio indicated significantly higher among hypothyroid group as compared to euthyroid group (p<0.05), whereas mean HDL level were significantly lower in hypothyroid group as compared to euthyroid group (p<0.05).

Table 2: Comparisons of lipid profile parameters in hypothyroid and euthyroid group

Mean serum levels of TC, TG, VLDL, LDL cholesterol and LDL/HDL ratio were significantly lower among hyperthyroid group as compared to  euthyroid  group (p<0.05), whereas mean HDL level were significantly higher in hyperthyroid group as compared to euthyroid group (p<0.05).

Table3: Comparisons of lipid parameters in hyperthyroid and euthyroid group

Although it is frequently under diagnosed, hypothyroidism is the second most prevalent endocrine condition behind diabetes mellitus. Numerous investigations have shown that hypothyroidism is associated with a variety of lipid problems. All metabolic pathways, including lipid metabolism, are influenced by thyroid hormone. Hypothyroidism can cause early atherosclerosis and its complications if left untreated. One of the main causes of human death and morbidity is atherosclerosis, which is the underlying cause of CAD in particular.

The current investigation revealed a female preponderance, which was consistent with research by Agarwal et al. [11] and Kebamo et al. [10]. There may be a sex difference in the prevalence of autoimmune illnesses, which could explain the higher prevalence of thyroid dysfunction in women.

In our study majority of the subjects were 41-50 years age group; concordance findings also reported by Al‑odat et al [12] and RK Yadav et al [13].

The average serum total cholesterol levels of the hypothyroid group were statistically substantially higher than those of the euthyroid group during the current study. Previous studies by Upadhyay P. et al. [15] and Bansal A. et al. [14] have reported a comparable rise in total cholesterol. The odified hepaticlipase activity could be one reason for this rise. Notably, a reduction in lipoprotein lipase activity has been associated with hypothyroidism.

According to Zhenjiang H. et al. [16] and Chaudhuri et al. [17], the average serum triglyceride level in the hypothyroid group was significantly higher than that of the normal euthyroid group. Reduced lipoprotein lipase activity is assumed to be the reason of the hypothyroid group's higher triglyceride levels. In patients with hypothyroidism, fractional clearance of endogenous and exogenous triglycerides is markedly decreased, but plasma triglyceride synthesis remains unchanged.

When compared to the euthyroid group, the hypothyroid group's HDL levels in our study dramatically dropped; our results are consistent with those of Madhura NS et al. [18] and Jawzal K et al. [19]. These results demonstrate that both overt and subclinical hypothyroidism have an atherogenic lipid profile.

The present study showed a significant reduction in total cholesterol, triglycerides, LDL, VLDL, and LDL: HDL ratio within the hyperthyroid group as compared to euthyroid group, our results were consistent with the Ramachandran, et al [20] and James SR, et al [21].

Current research discovered that the hypothyroid group's mean LDL/HDL ratio was much higher than the euthyroid group's. These outcomes are consistent with what K Ambrish, et al [22], and Ashwani, et al [23]

The hypothyroid group's mean LDL readings were statistically significantly higher than those of the euthyroid group, in accordance with the Machandrareddy, et al [24].Reduced fractional clearance of LDL particles may be the cause of this.

Dyslipidemia and thyroid dysfunction were found to be significantly correlated. The lipid profile, a major risk factor for cardiovascular diseases, may vary significantly as a result of dysregulated thyroid activity. Therefore, lipid profiles may be significantly impacted by thyroid disease. To lower or avoid the risk of atherosclerosis and cardiovascular illnesses, thyroid dysfunction screening is essential for all dyslipidemic individuals.

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