Clinical and laboratory evaluation of hyperlipemic and hypothyroid patients

Abstract

Objective -To determine the frequency of hypothyroidism in a sample of hyperlipemic patients and evaluate clinical and laboratory factors indicative of thyropathy among them. Methods -Fifty-one hyperlipemic patients, grouped according to an earlier or recent diagnosis of their thyroid function into euthyroid and hypothyroid, were evaluated with clinical and laboratory examinations of blood levels of free T 4 and TSH (by radioimmunoassay Clinical and Laboratory Evaluation of Hyperlipemic and Hypothyroid Patients Original ArticleHypothyroidism is a clinical syndrome resulting from a decrease in the thyroid hormones thyroxin (T 4 ) and triiodothyronine (T 3 ). It is classified as primary, secondary, or tertiary, according as to whether the cause of the disease is localized respectively in the thyroid, the hypophysis [resulting from thyroid stimulating hormone (thyrotrophin-TSH) deficiency], or the hypothalamus [resulting from TSH releasing hormone (TRH) deficiency]. In primary hypothyroidism a concomitant increase in thyrotrophin (TSH) occurs in an attempt to stimulate the thyroid gland to produce T4 and T3. In these cases, as long as healthy thyroid tissue is available, normalization of T 4 will occur, characterizing a condition of subclinical hypothyroidism 1 . Both subclinical and symptomatic hypothyroidism are associated with various risk factors for atherosclerotic disease, including systemic arterial hypertension, hypercholesterolemia, hypertriglyceridemia, increased lipoprotein a 2 , and endothelial dysfunction 2,3 . The occurrence of 2.6 to 10% of cases of hypothyroidism traced to hyperlipemia including its subclinical form could only be detected in the laboratory by increases in TSH and normal T 4 4-6 . Several studies suggest that hyperlipemic patients should be tested for the presence of hypothyroidism [4][5][6] . The objectives of the present work were to determine the frequency of hypothyroidism in patients seen at the dyslipemia outpatient clinic of the Clinics Hospital of the School of Medicine of Botucatu (HCFMB), to determine the frequency of the arrival of new cases of hypothyroidism in this clinic by analyzing patients' blood concentration of free T 4 and TSH, and to classify hyperlipemic patients, clinically and in the laboratory, according to their functional thyroid condition. MethodsFollowing exclusion of patients with disease conditions interfering with their lipid profile or thyroid function (diabetes mellitus and uremia) 7-9 51 of 85 patients followed at the outpatient dyslipemia clinic of the HCFMB between

Prevalence of Hypothyroidism in Patients with Dyslipidemia: Tehran Thyroid Study (TTS)

“…Vierhapper et al [23] showed increased LDL-C levels in overt hypothyroidism, although not significant. Since thyroid hormones activate the gene expression of the LDL-C receptor in the liver, variability in the association between lipid profile and hypothyroidism is probably related to the gene expression variation [1,8,13]. The results of our study, in contrast to the study of Decastro et al [13], showed that mean HDL-C did not differ in these 3 groups.…”

“…Since thyroid hormones activate the gene expression of the LDL-C receptor in the liver, variability in the association between lipid profile and hypothyroidism is probably related to the gene expression variation [1,8,13]. The results of our study, in contrast to the study of Decastro et al [13], showed that mean HDL-C did not differ in these 3 groups. Effects of overt hypothyroidism on HDL-C and TG levels have been variable [1,14,24]; after adjusting for sex and age, no significant association was found between high levels of TC, TG, LDL-C, or low HDL levels and overt or subclinical hypothyroidism.…”

Lipid Profile in Hypothyroid Patients: A Cross Sectional Study

“…Serum concentrations of high density lipoprotein cholesterol was reported to be higher among newly diagnosed hypothyroid patients (subclinical or clinical) whereas serum concentrations of HDL cholesterol were significantly lower among euthyroid and previously reported hypothyroid cases who were on thyroxine replacement therapy 8 . Studies done by Michalopoulou 21 , Diekman 22 , Tsmihodimos 23 and Olukoga 24 showed average serum concentration of HDL higher in subclinical or clinical hypothyroidism.…”

“…Serum concentration of high density lipoprotein cholesterol was reported to be higher among newly diagnosed hypothyroid patients with the value more than 40 mg/dL in subclinical or clinical hypothyroidism whereas serum concentrations of HDL cholesterol were significantly lower among euthyroid and previously reported hypothyroid cases who were on thyroid replacement therapy 8 . Hypothyroid patients usually exhibit elevated levels of high density lipoprotein cholesterol (HDL-C) mainly due to increased concentration of HDL2 particles 9 .…”

Plasma Thiobarbituric Acid-Reactive Substance Levels in Subclinical Hypothyroidism

“…Similarly, Milionis et al [17] have found no alteration on plasma paraoxonase-1 activity in subclinical hypothyroid patients before and after levothyroxine therapy. It has been shown in several studies that serum concentration of HDL could be increased in subclinical hypothyroidism [18,19] . The underlying mechanism of the elevated HDL concentration in hypothyroidism is not clear.…”