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Query: UMLS:C0242339 (dyslipidemia)
 13,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Disorders in lipoprotein metabolism (dyslipidemia) can result in premature atherosclerosis or pancreatitis. Dyslipidemias can be classified as hypercholesterolemia, hypertriglyceridemia, combined hyperlipidemia, and low levels of high density lipoprotein (HDL) cholesterol. All of the dyslipidemias can be primary or secondary. Both elevated levels of low density lipoprotein cholesterol and decreased levels of HDL cholesterol predispose to premature atherosclerosis. Triglyceride levels greater than 1,000 mg/dL increase the risk for pancreatitis. In the appraisal of the dyslipidemias, measurement of serum cholesterol, triglycerides, HDL-cholesterol and obtaining the LDL cholesterol by Friedewald equation is usually sufficient in the majority of patients. However, in some cases, such as the diagnosis of the Type III dyslipidemia and when triglycerides are > or = 400 mg/dL, ultracentrifugation is required to determine the VLDL or LDL cholesterol. Lipoprotein electrophoresis can be useful in the diagnosis of Type III dyslipidemia (broad beta band) and also to detect chylomicrons. In young subjects with coronary artery disease with a normal LDL cholesterol an apolipoprotein B-100 level may be a useful test. In children and young adults with severe hypertriglyceridemia, measurement of lipoprotein lipase activity or assaying apolipoprotein C-II levels can be useful in elucidating the cause. Also, laboratory tests are useful in excluding a secondary cause of dyslipidemia (urinalysis, plasma creatinine, TSH, glucose, protein electrophoresis, alkaline phosphatase and transaminases). Thus, laboratory investigations play an important role in the management of dyslipidemia.
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PMID:A practical approach to the laboratory diagnosis of dyslipidemia. 870 23

Thyroid hormones influence all major metabolic pathways. Their most obvious and well-known action is an increase in basal energy expenditure obtained acting on protein, carbohydrate and lipid metabolism. With specific regard to lipid metabolism, thyroid hormones affect synthesis, mobilization and degradation of lipids, although degradation is influenced more than synthesis. The main and best-known effects on lipid metabolism include: (a) enhanced utilization of lipid substrates; (b) increase in the synthesis and mobilization of triglycerides stored in adipose tissue; (c) increase in the concentration of non-esterified fatty acids (NEFA); and (d) increase of lipoprotein-lipase activity. While severe hypothyroidism is usually associated with an increased serum concentration of total cholesterol and atherogenic lipoproteins, the occurrence of acute myocardial infarction (AMI) in hypothyroid patients is not frequent. However, hypothyroid patients appear to have an increased incidence of residual myocardial ischemia following AMI. Even in subclinical hypothyroidism, which is characterized by raised serum TSH levels with normal serum thyroid hormone concentrations, mild hyperlipidemia is present and may contribute to an increased risk of atherogenesis. Prudent substitution therapy with L-thyroxine is indicated in patients with both overt and subclinical hypothyroidism, with or without angina, to counteract the cardiovascular risk resulting from hyper-dyslipidemia.
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PMID:Thyroid and lipid metabolism. 1099 23

The composition and the transport of lipoproteins are seriously disturbed in thyroid diseases. Overt hypothyroidism is characterized by hypercholesterolaemia and a marked increase in low-density lipoproteins (LDL) and apolipoprotein B (apo A) because of a decreased fractional clearance of LDL by a reduced number of LDL receptors in the liver. The high-density lipoprotein (HDL) levels are normal or even elevated in severe hypothyroidism because of decreased activity of cholesteryl-ester transfer protein (CETP) and hepatic lipase (HL), which are enzymes regulated by thyroid hormones. The low activity of CETP, and more specifically of HL, results in reduced transport of cholesteryl esters from HDL(2) to very low-density lipoproteins (VLDL) and intermediate low-density lipoprotein (IDL), and reduced transport of HDL(2) to HDL(3). Moreover, hypothyroidism increases the oxidation of plasma cholesterol mainly because of an altered pattern of binding and to the increased levels of cholesterol, which presents a substrate for the oxidative stress. Cardiac oxygen consumption is reduced in hypothyroidism. This reduction is associated with increased peripheral resistance and reduced contractility. Hypothyroidism is often accompanied by diastolic hypertension that, in conjunction with the dyslipidemia, may promote atherosclerosis. However, thyroxine therapy, in a thyrotropin (TSH)-suppressive dose, usually leads to a considerable improvement of the lipid profile. The changes in lipoproteins are correlated with changes in free thyroxine (FT(4)) levels. Hyperthyroidism exhibits an enhanced excretion of cholesterol and an increased turnover of LDL resulting in a decrease of total and LDL cholesterol, whereas HDL are decreased or not affected. The action of thyroid hormone on Lp(a) lipoprotein is still debated, because both decrease or no changes have been reported. The discrepancies are mostly because of genetic polymorphism of apo(a) and to the differences between the various study groups. Subclinical hypothyroidism (SH) is associated with lipid disorders that are characterized by normal or slightly elevated total cholesterol levels, increased LDL, and lower HDL. Moreover, SH has been associated with endothelium dysfunction, aortic atherosclerosis, and myocardial infarction. Lipid disorders exhibit great individual variability. Nevertheless, they might be a link, although it has not been proved, between SH and atherosclerosis.
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PMID:Thyroid disease and lipids. 1203 52

Obesity and starvation have opposing affects on normal physiology and are associated with adaptive changes in hormone secretion. The effects of obesity and starvation on thyroid hormone, GH, and cortisol secretion are summarized in Table 1. Although hypothyroidism is associated with some weight gain, surveys of obese individuals show that less than 10% are hypothyroid. Discrepancies have been reported in some studies, but in untreated obesity, total and free T4, total and free T3, TSH levels, and the TSH response to TRH are normal. Some reports suggest an increase in total T3 and decrease in rT3 induced by overfeeding. Treatment of obesity with hypocaloric diets causes changes in thyroid function that resemble sick euthyroid syndrome. Changes consist of a decrease in total T4 and total and free T3 with a corresponding increase in rT3. untreated obesity is also associated with low GH levels; however, levels of IGF-1 are normal. GH-binding protein levels are increased and the GH response to GHRH is decreased. These changes are reversed by drastic weight reduction. Cortisol levels are abnormal in people with abdominal obesity who exhibit an increase in urinary free cortisol but exhibit normal or decreased serum cortisol and normal ACTH levels. These changes are explained by an increase in cortisol clearance. There is also an increased response to CRH. Treatment of obesity with very low calorie diets causes a decrease in serum cortisol explained by a decrease in cortisol-binding proteins. The increase in cortisol secretion seen in patients with abdominal obesity may contribute to the metabolic syndrome (insulin resistance, glucose intolerance, dyslipidemia, and hypertension). States of chronic starvation such as seen in anorexia nervosa are also associated with changes in thyroid hormone, GH, and cortisol secretion. There is a decrease in total and free T4 and T3, and an increase in rT3 similar to findings in sick euthyroid syndrome. The TSH response to TRH is diminished and, in severe cases, thyroid-binding protein levels are decreased. In regards to GH, there is an increase in GH secretion with a decrease in IGF-1 levels. GH responses to GHRH are increased. The [table: see text] changes in cortisol secretion in patients with anorexia nervosa resemble depression. They present with increased urinary free cortisol and serum cortisol levels but without changes in ACTH levels. In contrast to the findings observed in obesity, the ACTH response to CRH is suppressed, suggesting an increased secretion of CRH. The endocrine changes observed in obesity and starvation may complicate the diagnosis of primary endocrine diseases. The increase in cortisol secretion in obesity needs to be distinguished from Cushing's syndrome, the decrease in thyroid hormone levels in anorexia nervosa needs to be distinguished from secondary hypothyroidism, and the increase in cortisol secretion observed in anorexia nervosa requires a differential diagnosis with primary depressive disorder.
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PMID:Effect of obesity and starvation on thyroid hormone, growth hormone, and cortisol secretion. 1205 88

The stress system coordinates the adaptive responses of the organism to stressors of any kind.(1). The main components of the stress system are the corticotropin-releasing hormone (CRH) and locus ceruleus-norepinephrine (LC/NE)-autonomic systems and their peripheral effectors, the pituitary-adrenal axis, and the limbs of the autonomic system. Activation of the stress system leads to behavioral and peripheral changes that improve the ability of the organism to adjust homeostasis and increase its chances for survival. The CRH and LC/NE systems stimulate arousal and attention, as well as the mesocorticolimbic dopaminergic system, which is involved in anticipatory and reward phenomena, and the hypothalamic beta-endorphin system, which suppresses pain sensation and, hence, increases analgesia. CRH inhibits appetite and activates thermogenesis via the catecholaminergic system. Also, reciprocal interactions exist between the amygdala and the hippocampus and the stress system, which stimulates these elements and is regulated by them. CRH plays an important role in inhibiting GnRH secretion during stress, while, via somatostatin, it also inhibits GH, TRH and TSH secretion, suppressing, thus, the reproductive, growth and thyroid functions. Interestingly, all three of these functions receive and depend on positive catecholaminergic input. The end-hormones of the hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoids, on the other hand, have multiple roles. They simultaneously inhibit the CRH, LC/NE and beta-endorphin systems and stimulate the mesocorticolimbic dopaminergic system and the CRH peptidergic central nucleus of the amygdala. In addition, they directly inhibit pituitary gonadotropin, GH and TSH secretion, render the target tissues of sex steroids and growth factors resistant to these substances and suppress the 5' deiodinase, which converts the relatively inactive tetraiodothyronine (T(4)) to triiodothyronine (T(3)), contributing further to the suppression of reproductive, growth and thyroid functions. They also have direct as well as insulin-mediated effects on adipose tissue, ultimately promoting visceral adiposity, insulin resistance, dyslipidemia and hypertension (metabolic syndrome X) and direct effects on the bone, causing "low turnover" osteoporosis. Central CRH, via glucocorticoids and catecholamines, inhibits the inflammatory reaction, while directly secreted by peripheral nerves CRH stimulates local inflammation (immune CRH). CRH antagonists may be useful in human pathologic states, such as melancholic depression and chronic anxiety, associated with chronic hyperactivity of the stress system, along with predictable behavioral, neuroendocrine, metabolic and immune changes, based on the interrelations outlined above. Conversely, potentiators of CRH secretion/action may be useful to treat atypical depression, postpartum depression and the fibromyalgia/chronic fatigue syndromes, all characterized by low HPA axis and LC/NE activity, fatigue, depressive symptomatology, hyperalgesia and increased immune/inflammatory responses to stimuli.
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PMID:Hypothalamic-pituitary-adrenal axis, neuroendocrine factors and stress. 1237 95

Dyslipidemia and obesity are common in adult patients with hypopituitarism. Possible contributions of age, sex and hormone deficiencies to hypercholesterolemia and obesity in adult hypopituitary patients were analyzed in 1, 272 Japanese cases based on a database of a national survey on adult hypopituitarism. In patients on routine hormone replacement therapy, 30.5% of male and 40.7% of female subjects were considered hypercholesterolemic. In univariate analysis, hypercholesterolemia was more prevalent in female, aged, untreated Gn-deficient and TSH-deficient groups. In multivariate analysis, sex of female, age older than 40 yr and TSH deficiency were the independent contributing factors to hypercholesterolemia. Obesity (body mass index (BMI) > or = 25 kg/m2) was more prevalent in male, TSH-deficient and ADH-deficient groups. Severe obesity (BMI > or = 30) was observed in high prevalence in the youngest group. These findings suggest that hypercholesterolemia and obesity were prevalent in different age and gender groups in Japanese adult patients with hypopituitarism. Insufficient replacement of thyroid hormone and possibly gonadotropin deficiency might contribute to hypercholesterolemia. In contrast, hypothalamic dysfunction as well as hormone deficiencies might play roles in obesity in these patients.
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PMID:Hypercholesterolemia and obesity in adult patients with hypopituitarism: a report of a nation-wide survey in Japan. 1470 49

Hyperlipidemia is a secondary disorder associated with many metabolic disorders including hypothyroidism. The occurrence of dyslipidemia in subclinical hypothyroidism is controversial. Hyperphosphatemia may accompany the dyslipidemia in some metabolic disorders. Both hyperlipidemia and hyperphosphatemia are considered to be risk factors for the coronary heart diseases. In the present study, we investigated the occurrence of dyslipidemia and altered serum phosphate concentrations in patients with thyroid disorders. The results indicated a significantly elevated serum cholesterol and triglyceride concentrations in the hypothyroid patients. The dyslipidemia was accompanied with significantly elevated serum phosphate level. On the other hand, no significant difference was evident in the serum lipid or phosphate concentrations of subclinical hypothyroid patients compared to euthyroid subjects. A significantly reduced serum phosphate level was shown in hyperthyroid patients with unaltered serum lipid levels. Significant correlations were evident between TSH and T(4) levels as independent parameters and the serum concentrations of triglyceride, cholesterol and phosphate. The results indicate in hypothyroidism that a secondary hyperphosphatemia may aggravate myocardial and arterial abnormalities induced by the secondary hyperlipidemia, which may need correction.
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PMID:The secondary dyslipidemia and deranged serum phosphate concentration in thyroid disorders. 1501 Feb 97

Subclinical hypothyroidism (sHT) is associated with dyslipidemia and enhanced cardiovascular risk. We assessed carotid artery intima-media thickness (IMT, high-resolution ultrasonography) and lipoprotein profile in 45 sHT patients (aged 37 +/- 11 yr) at baseline and after 6 months of randomized, placebo-controlled L-T(4) replacement. In comparison with 32 age- and sex-matched controls, sHT patients had elevated total and low-density lipoprotein (LDL) cholesterol and ApoB levels (P = 0.002, P = 0.0007, and P = 0.01, respectively) and higher mean-IMT values (P < 0.0001). In stepwise regression analysis, mean-IMT was positively related (r(2) = 0.71, P < 0.0001) to age, TSH, and LDL cholesterol. L-T(4) replacement significantly reduced both total and LDL cholesterol (P < 0.0001 for both) and mean-IMT (by 11%, P < 0.0001). The decrement in IMT was directly related to the decrements of both total cholesterol and TSH (P = 0.02 and P = 0.0001, respectively). We conclude that early carotid artery wall alterations are present in sHT patients. Whether such IMT increase is related to an early atherosclerotic involvement of the arterial wall cannot be clearly decided on the basis of the present results. However, the fact that L-T(4) replacement therapy was able to improve both the atherogenic lipoprotein profile and intima-media thickening suggests that lipid infiltration of arterial wall may represent a major mechanism underlying IMT increase in subclinical hypothyroidism.
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PMID:Effect of levothyroxine replacement on lipid profile and intima-media thickness in subclinical hypothyroidism: a double-blind, placebo- controlled study. 1512 26

Cushing's syndrome is characterized by endogenously increased production of glucocorticoids. The activity of immune system is regulated mainly by two systems in the body. Glucocorticoids and NF-kappaB counteract the effects of each other on the immune system. It has been reported that immune response is exaggerated after the amelioration of Cushing's syndrome. We report a rare case of exacerbation of Graves' disease after unilateral adrenalectomy for Cusing's syndrome. A 50-yr-obese woman with hypertension, dyslipidemia, impaired glucose tolerance and insulin resistance wasadmitted to outpatients clinic of endocrinology. The results of evaluation of glucocorticoids metabolism and adrenal magnetic resonance imaging revealed the Cusing's syndrome. We also assessed thyroid function tests because of the diagnosis of goiter and thyroid hormone replacement in her medical history, and the presence of exophthalmia and tachycardia in examination. Althoug TSH level was detected at the lower border of normal range, free T4 and free T3 were in normal range and autoantibody of thyroidal peroxidase and thyroglobulin was higer than normal reference range. An operation was performed and a mass was removed from her left adrenal gland. The pathologic examination confirmed adrenal adenoma. She was re-admitted to the outpatient clinic 9 months after with complaints of palpitation, malaise and weight loss. Tests carried out to determine the thyroid function revealed Graves' disease. We prescribed propylthiouracil and beta-blocker treatment.
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PMID:Exacerbations of Graves' disease after unilateral adrenalectomy for Cushing's syndrome. 1571 57

Pulse wave velocity (PWV) is known to represent arterial stiffness and is established as a marker for cardiovascular risk and a prognostic factor for mortality in the case of chronic renal failure or hypertension. The application of an automated apparatus for measuring brachial-ankle pulse wave velocity (baPWV) has made PWV measurement non-invasive, easier to screen for cardiovascular risk and as a result, baPWV measurements have become widely applied in clinical practice in recent years. We assessed the baPWV in 7 flank hypothyroidism patients and 28 subclinical hypothyroidism patients. In comparison with age matched healthy controls, 3 hypothyroid patients had advanced values and by replacement therapy, all 7 subjects showed improvement in their baPWV values (1531.2 +/- 242.7 to 1330.2 +/- 208.6 cm/s, p<0.05). In 28 subclinical hypothyroid subjects, 71% also had accelerated baPWV values for their age. Ten subjects (36% of all) had neither hypertension, hyperlipidemia, diabetes nor were taking any medication, and yet 8 patients out of 10 showed advanced baPWV values compared to age matched mean values. The baPWV was not correlated to TSH or total cholesterol levels, and was associated with only age and blood pressure (p = 0.01, <0.001, respectively), which are widely demonstrated as the characteristics for baPWV. In two subclinical hypothyroid subjects, who were normotensive and had no dyslipidemia, thyroxine treatment was performed and the baPWV decreased with unchanged blood pressure and total cholesterol levels. We concluded that the arterial wall stiffness tends to be increased in both overt and subclinical hypothyroid patients, and an appropriate treatment could reverse the abnormalities. It is possible that the initiation of adequate treatment in subclinical hypothyroidism may reduce the cardiovascular risk.
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PMID:Increased risk for atherosclerosis estimated by pulse wave velocity in hypothyroidism and its reversal with appropriate thyroxine treatment. 1575 64


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