Pattern of Dyslipidemia in Hypothyroid Patients-A cross sectional study

Background: An association between thyroid dysfunction and dyslipidemia prevails. Levels of total cholesterol, low density lipoprotein cholesterol, triglycerides tend to increase as thyroid function declines. Objective: To find out the pattern of dyslipidemia in hypothyroid patients. Methods: Sixty cases were selected as a sample of convenience in this cross sectional study from in-patient department of Medicine and Endocrinology, BSMMU. Meticulous history taking and thorough clinical examinations were done. Report of lipid profile and thyroid function tests were recorded from patients file. All the information's were recorded in a pre-desigaed structured questionnaire. Collected data were classified, edited, coded and entered into the computer for statistical analysis by using SPSS. Results: Among the 60 cases, 43 (72%)were female; 17(28%) were male. Age range was24-59 years with a mean age of 38.80 (+10.35) years. Majority 38(65%) were housewife, followed by service holder Il(18.33%),08(13.3%) were business men and O2(3.3%) had other occupations. Majority 42(70%) patients were taking thyroxin. Mean Total cholesterol (TC), LDL cholesterol, Triglyceride (TG) and HDL were222.20(+42.25); 138.63(+31.51); 243.36(+83.13) and 37.30(+5.12) respectably. Conclusion: All hypothyroid subjects had dyslipidemia. The present study indicated that hypothyroidism was associated with an abnormal lipid profile, especially with respect to the levels of total cholesterol and triglyceride.

mediated catabolism of LDL and LDL is the main cause of the hypercho lesterolemia ob s erved in hypothyroidi sm. 6us hypothyroidism constitutes a significant cause of secondary dislipidemia. 7rum concentration of high density lipoprotein (HDL) cholesterol.was reported to be higher among newly diagnosed hypothyroid patients whereas serum concentra- tion of HDL cholesterol were signific antly lower among euthyroid and previously reported hypothyroid cases who were on thyroid replacement therapy.tIt is mainly due to increased concentration of HDL particles.eHDL choles- terol level was found reduced in some studies on hypothy- Hypothyroidism is a clinical syndrome resulting from a deficiency of thyroid hormones, which in turn results in a generahzed slowing down of metabolic process.lIt is a common metabolic disorder in general populatton.zThe thyroid dysfunction increases with dga, especially in women. 3Hypothyroidism is associated with many biochemical abnormalities.An association between thyroid dysfunction and dyslipidemia was first reported in 1930.4Levels of total cholesterol (TC) and low density lipoprotein (LDL) cholesterol tends to increase as thyroid function declines.2Decreased thyroid secretion greatly increase the plasma concentration of cholesterol because of decreased rate of cholesterol secretion in the bile and consequent diminished loss in the faeces due to decreased number of LDL receptors on liver cells.sDecreased activ- ity of LDL receptors resulting in decreased receptor-  Many studies were done regarding the biochemical status of hypothyroid patients including lipid profile and its consequences in developed countries but there is no such study in our population.In our country hypothyroid cases are diagnosed late due to limited health facilities and many other reasons which may lead to more adverse consequences in our population.So, we have designed this study for evaluation of TC, HDL, LDL and TG level in hypothyroid patients.

Methods :
This Cross-sectional study was conducted in the Indoor and Outdoor patient Department (OPD) of Medicine & Endocrinology, Bangabandhu Sheikh Mujib Medical Universify from July 2012 to December 2012.A total of 60 cases were selected by convenient sampling.Clinically and biochemically diagnosed cases of hypothyroidism with age ranges between 12 to 60 years, irrespective of sex, whether or not on thyroxine were included.Patients with known secondary hypothyroidism, chronic renal failure, diabetes mellifus, liver diseases, pregnancy, were on lipid lowering medications and who did not give consent were excluded.Informed written consent was taken from the patients.Socio-demographic and relevant information were gathered through face to face interview, general medical condition of the patients was evaluated through history, physical examination and with the help of investigations .Datawere collected in a predesigned structured questionnaire.After collection, data editing and clearing was done manually and the data were entered in a computer and analysis was done by using SPSS version 14.
Those who had LDL level <130 mg/dl showed mean TSH Though Iodine deficiency is endemic in Bangladesh, the magnitude of thyroid problem and its consequences is not-entirely known and the exact relationships to other 1,57 20t3 Jul is a clinical state resulting from an insufficient aruount of circulating thyroid hormone to support nonnal body function.It may exist in utero or develop in infancy, child- hood or even in adult life.This is a cross-sectional study, was conducted to compare lipid profile status in hypothy- roid patients.
Thyroid disorders are known to influence lipid metabo- lism and are common in dyslipidemic patients.llThese hormones appear to serve as a general pacemaker, acceler- ating the metabolic processes and they may also be associ- ated with metabolic syndromes.l2The serum cholesterol level generally varies inversely with the thyroid activity.13 This condition is more conlmon in the elderly.laAlso, women are more likely than men to develop thyroid disease."In this study, the percentage of female subjects in the hypothyroid group was signific arftLy higher than that of the male subjects.Moreover, the hypothyroid respondents were more commonly found in the elderly group rather than in the young or the middle aged groups.
These results were well correlated with the findings of other research groups.l4'rsSerum total cholesterol was significantly increased in the hypothyroid subjects.Some other studies have also supported this finding.16Specifi cally, the thyroid hormone stimulates the hepatic de novo cholesterol synthesis by inducing HMG-CoA reductase that catalyzes the conversion of HMG-Co A to Mevalonate, the first step in the biosynthesis of cholesterol.lTDespite the reduced activity of HMG- CoA reductase, hypercholesterolaemia in hypothyroidism probably results from the reduced catabolism of lipoproteins, a phenomenon that may be explained by a decreased expression of lipoprotein receptors and 158 LDL cholesterol."Hypothyroid patients usually exhibit elevated levels of HDL, mainly due to the decreased activity of the cholesterol ester transfer protein (CETP), resulting in reduced transfer of cholesteryl esters from HDL to VLDL, thus increasing the HDL cholesterol levels.Furtherrnore, the decreased activity of hepatic lipase (HL) leads to the decreased catabolism of HDL2 HDL OR }JDL2 Particles."But no significant difference was found between these groups and the values remained within the reference range.This result corroborated the findings of a previous study.14The serum triglyceride levels were also higher in the subjects with hypothyroidism, which concuffed with the reports of a previous sfudy.l2These changes were attributable to the decreased activity of lipoprotein lipase (LPL), which resulted in a decreased clearance of triglyceride-rich lipoproteins.l7Allthese abnormalities resolved as the serum T4 concentration became normal."Furthefinore, the clearance of the chylomicron remnants was found to be decreased in hypothyroidism."Higher TC and TG were observed to be common in hypothyroidism.But no significant relation was found for HDL and LDL.
Hypothyroidism has been generally considered as a cardiovascular risk factor in a majority of sfudies, mainly because of its association with elevated serum total and LDL cholesterol.Important associations have been identi- fied for other risk factors for atherosclerosis.
The present study indicated that hypothyroidism was associated with an abnormal lipid profile, especially with respect to the levels of TC and TG.Hence, persons suffering from hypothyroidism should make lifestyle and dietary adjustments to avoid future cardiovascular complications.A large-scale study is warranted to further validate the findings of the present study.

Conclusion :
A11 hypothyroid subjects had dyslipidemia.The present study indicated that hypothyroidism was associated with an abnormal lipid profile, especially with respect to the levels of TC and TG.
roid patients.eDecreased thyroid secretion greatly increases the plasma concentration of triglycerides.tIt is due to decreased activity of lipoprotein lipase (LPL), which results in decreased clearance of triglyceride lipoproteins.2Multiple epidemiologic studies have demonstrated a strong relationship between serum cholesterol and Introduction : coronary heart disease (CHD).Randomized controlled clinical trials have unequivocally documented that lower- ing plasma cholesterol reduces the risk of clinical events due to atheroselerosis.loSo earLy diagnosis and proper management signific antly reduce the mortality and morbidity of dyslipidemic cardiovascular diseases.

Table - V
Mean TSH and FT4 according to Triglyceride gG) level

Table - II
Thyroxine taken or not taken in the study population

Table - III
Mean TSH and FT4 with Total cltolesterol (fq kvel