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Table of Content - Volume 21 Issue 3 - March 2022


 

Elevated lipid profile in hypothyroidism patients and risk of CAD

 

Suresh Ade1, Deepali Vidhate2, Sandhya Jathar2, Mahesh Padsalge3*, Thomas Becky4, Murarka Arpith5,

Honey Mittal5, Vivek Harikumar5, Vidisha Jariwala5, Thomas James6

 

1Assistant Professor, Department of Medicine, {2Professor, Department of Biochemistry}, {5MBBS Student}, D Y Patil Deemed to Be University School of Medicine and Hospital, Nerul, Navi Mumbai, INDIA.

3Associate Professor, Department of Medicine, 6Department Of Cardiovascular and Thoracic Surgery (CVTS), D Y Patil School of Medicine and Hospital, Nerul, Navi Mumbai, INDIA.

4Professor Head Research, Christ Deemed to Be University, Lavasa, Pune, INDIA.

Email: drmaheshpadsalge@gmail.com

 

Abstract              Background: Hypothyroidism and dysfunctional thyroid gland is one of the major conditions observed in the middle-aged population. It has been observed that females are more prone for hypothyroidism. Further it has also been observed that obesity, deranged lipid profile, high blood sugar and hypertension were the common features in most of the cases. Metabolic syndrome was considered to play a key role in hypothyroidism. Various factors are associated with it and the molecular cascade is not yet very well understood. The aim of the present study is to evaluate the association between the risk of CAD in hypothyroidism. Results: Serum cholesterol were observed high in hypothyroidism cases than controls [250.75 (±40.15)/ 180.32 (±34.42)], triglycerides concentration was also increased in hypothyroidism cases than controls [285.91(±65.55)/ 125.45(±48.86)]. While decreased levels of HDL were observed in hypothyroidism cases than controls. Fasting blood glucose and HbA1c were significantly high in hypothyroidism group as compared to controls. Conclusion: The present study observed high WC, Deranged lipid profile, hyperglycaemia and high BP in hypothyroidism cases than controls.

Key words: Hypothyroidism, Lipid profile, CAD

 

INTRODUCTION

Hypothyroidism is one of the common endocrine disorders observed mostly in females of peri and post-menopausal phase. Most of the times it remains undiagnosed due to various reasons. It may be due to the similarity of symptoms with that of menopausal period. Early diagnosis and thyroid hormone replacement therapy may play an important role in prevention as well progression of atherosclerosis.1,2 In hypothyroidism it has been observed that there is increase in weight, BMI.3,4 High levels of TSH were observed due to insufficiency of thyroid gland towards the secretion of thyroid hormones. Hence the treatment is based mainly on TSH levels. Due to low levels of thyroid hormone various metabolic pathways are affected. Derangements in metabolism leads to weight gain due to accumulation of TG.5,6 Low levels of T3 also affects the uptake of cholesterol by liver. Hence circulatory levels of LDL were increased. Higher levels of LDL increase the risk of atherosclerosis and mainly associated with CAD.7-9 The present study was carried out to understand the biochemical reason for the derangements in metabolism and its association with CAD in hypothyroidism patients. The aim of the present study is to evaluate the association of metabolic syndrome in hypothyroidism.

 

METHODS
In the present study 123 hypothyroidism cases and 154 controls were enrolled.
The present study was carried out at D.Y. Patil hospital, Nerul, Navi Mumbai. Patients were recruited from outpatient department (OPD) and Indoor patient department (IPD). Informed consent was obtained in written form from all the study participants.

Inclusion criteria: Newly diagnosed hypothyroidism cases.

Exclusion criteria: Chronic Hypothyroidism cases on medication, pregnant females. Age and sex matched healthy individuals without clinical evidence of hypothyroidism. Fasting venous blood samples were collected from hypothyroidism cases and controls. Routine biochemical tests were performed on autoanalyzer.

 

RESULTS

The present study observed a significant difference in Body Mass Index (BMI) [25.7(±2.35)/ 22.9 (±2.84)]. Circulatory levels of cholesterol were elevated in hypothyroidism cases than controls [250.75 (±40.15)/ 180.32 (±34.42)], further triglycerides were also shown increased concentration in hypothyroidism cases than controls [285.91(±65.55)/ 125.45(±48.86)]. Lower levels of HDL have been observed in hypothyroidism cases than controls. Even Fasting blood glucose and HbA1c were significantly elevated in hypothyroidism group as compared to controls.


 

Table 1: Clinical and Biochemical Characteristics of study subjects

Variables

Hypothyroidism (n=123)

Controls (n=154)

P value

Age

55.79(± 10.8)

44.22(± 12.8)

NS

Males %

41

46

NS

Females %

49

54

NS

BMI

25.7 (±2.35)

22.9 (±2.84)

NS

FBS (mg%)

127.66 (±55.49)

96.37 (±28.36)

0.000

HbA1c (mg%)

7.09 (±1.77)

5.72 (±1.43)

0.000

Insulin

12.39 (±8.84)

9.64 (±6.00)

0.004

Triglycerides (mg%)

285.91 (±65.55)

125.45 (±48.86)

0.001

Cholesterol (mg%)

250.75 (±40.15)

180.32 (±34.42)

0.001

LDL (mg%)

110.52 (±43.30)

105.20 (±42.50)

0.005

HDL (mg%)

36.27 (±15.12)

49.35 (±17.45)

0.001

 

Table 2: Correlation of TSH with circulatory Cholesterol, TG levels

Variable

r2

P

TSH/ Serum Cholesterol

0.843

0.000*

TSH/ Serum Triglycerides

0.606

0.001*

 In the present study significantly more cases of metabolic syndrome patients were observed in hypothyroidism subjects. Pearson’s correlation showed a significant association of TSH levels with serum cholesterol.

 


DISCUSSION

This present study showed a significant variation in lipid profile, blood sugar and blood pressure in hypothyroidism cases than controls. The present study reported the incidence of metabolic syndrome with hypothyroidism acts as a risk factor for development of fatty liver and even associated with development of CAD. Low rate of removal of LDL from circulation is thought to be due to diminished LDL receptors in the liver with lesser receptor functioning.12-15 It has been also reported that, liver-specific enzyme 7α-hydroxylase is inhibited by T3. This results in lowering the rate of cholesterol catabolism. As a result, higher levels of serum cholesterol were found in hypothyroidism.13,14 Hence the risk of CAD in hypothyroidism patients actually linked with hypercholesterolemia due to lower T3 levels.15 Medications such as thyroid hormone tables reverse the risk ratio by maintaining T3 levels. If it remained un-diagnosed it may result in atherogenesis and CAD. Thyroid hormone is a key regulator of lipogenesis, fatty acid β-oxidation, cholesterol synthesis and the reverse cholesterol transport. Thyroid hormones primary hormonal target is liver. Liver is a central organ for metabolism. Derangement in thyroid profile will affect liver. The lower levels of thyroid hormones result in stimulation of anabolic pathways lipid metabolism and slowdown of lipid oxidative pathways. Hence low levels thyroid hormone is also associated with metabolic diseases involving the liver, like hypercholesterolemia and NAFLD.10,11 Thyroid hormone is crucial for normal lipid metabolism and many studies observed that a dysfunctional thyroid gland was associated with high lipid profile.5 While elevated parameters of lipid profile did not affect the thyroid function. Han and colleagues demonstrated that excess iodine combined with high-fat diet could cause damage to thyroid glands and lead to thyroid hormone disorder in mice. In another study, Shao and colleagues found that rats fed a high-fat lard diet for 24 weeks had significantly increased serum triglyceride levels in both the serum and thyroid tissue, decreased serum total T4 and free T4 levels in parallel with elevated serum TSH levels, and altered macro and micro morphology of the thyroid gland. Further researches are warranted to evaluate the potential role of dietary factors that may influence the occurrence of thyroid hypofunction in the susceptible population.

 

REFERENCES

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