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Query: UMLS:C0020473 (hyperlipidemia)
 15,891 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypothyroidism is a cause of secondary hyperlipidaemia. This study investigates the frequency of biochemically diagnosed hypothyroidism and its relationship with plasma cholesterol concentration in apparently healthy people. Thyroid function tests (total T4, TSH, and free T4) were performed on 272 apparently healthy men and women (179 vegetarians, 93 meat eaters) with a plasma cholesterol concentration above 7 mmol/l and on 90 individuals with a plasma cholesterol below 4.1 mmol/l who were matched for age, sex and dietary habits. Six per cent of those with a plasma cholesterol above 7 mmol/l had biochemical evidence of hypothyroidism as defined by a TSH greater than 10 mIU/l (reference range 1-6) and a low free T4 below 10 pmol/l (reference range 10.1-25). Eighty per cent of these people had a high titre of thyroid anti-microsomal antibodies. Of the 90 individuals with a plasma cholesterol level below 4.1 and the 25 randomly selected participants none had biochemical evidence of hypothyroidism. Hypothyroidism is relatively common in apparently healthy people with a raised plasma cholesterol. It appears no commoner in vegetarians than in meat eaters.
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PMID:Asymptomatic hypothyroidism and hypercholesterolaemia. 143 76

Hypothyroidism is associated with an increased risk of coronary artery disease. This observation may in part be related to the lipid abnormalities in patients with this condition. The lipid profiles of 268 patients with primary hypothyroidism and 27 with secondary hypothyroidism, who were examined in the Thyroid Clinic at the Mayo Clinic during a 1-year period, were reviewed. Hyperlipidemia was commonly associated with both primary and secondary hypothyroidism. The lipid values decreased with treatment of hypothyroidism. Type IIa hyperlipidemia was the most common lipid abnormality in patients with primary hypothyroidism, whereas type IIb was the most common in those with secondary hypothyroidism. Total/high-density lipoprotein cholesterol and low-density lipoprotein/high-density lipoprotein cholesterol ratios were increased in both male and female patients with primary and secondary hypothyroidism, and they decreased with restitution of the euthyroid state, although this decrease achieved statistical significance only in female patients. Significant associations with total thyroxine were noted for total cholesterol and triglycerides and with thyroid-stimulating hormone (thyrotropin) for total cholesterol and low-density lipoprotein cholesterol. Thus, both primary and secondary hypothyroidism are commonly associated with an atherogenic lipid profile, which improves with replacement of thyroid hormone. Even after restitution of the euthyroid state, however, the lipid profile remains atherogenic in male patients. In comparison with primary hypothyroidism, the lipid profile is more atherogenic in secondary hypothyroidism because of the lower high-density lipoprotein cholesterol levels associated with this condition.
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PMID:Hyperlipidemia in patients with primary and secondary hypothyroidism. 837 4

Thyroid hormone directly affects the heart and peripheral vascular system. The hormone can increase myocardial inotropy and heart rate and dilate peripheral arteries to increase cardiac output. An excessive deficiency of thyroid hormone can cause cardiovascular disease and aggravate many preexisting conditions. In severe systemic illness and after major surgical procedures changes in thyroid function can occur, leading to the "euthyroid sick syndrome." Patients will have normal or decreased levels of T4, decreased free and total T3, and usually normal levels of thyroid stimulating hormone. This syndrome may be an adaptive response to systemic illness that usually will revert to normal without hormone supplementation as the illness subsides. Recently, however, many investigators have explored the benefits of thyroid hormone supplementation in those diseases associated with euthyroid sick syndrome. Thyroid hormone's effects on the cardiovascular system make it an attractive therapy for those patients with impaired hemodynamics and low T3. Thyroid hormone has also been considered a treatment for patients with congestive heart failure, for patients undergoing cardiopulmonary bypass and heart transplantation, and for patients with hyperlipidemia. At present there is no evidence suggesting a favorable treatment outcome using thyroid hormone supplementation for any systemic condition except in those patients with documented hypothyroidism.
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PMID:Thyroid hormone and cardiovascular disease. 948 64

The development of sensitive assays for thyrotropin (TSH) has led to the discovery that many older patients have abnormal TSH levels without other alterations in serum thyroid hormone levels, conditions termed subclinical hypothyroidism (isolated elevation of TSH levels) and subclinical hyperthyroidism (isolated suppression of TSH levels). Subclinical hypothyroidism occurs in 5% to 10% of elderly subjects, and is especially prevalent in elderly women. Subclinical hyperthyroidism is less common, affecting less than 2% of the elderly population. The causes of subclinical thyroid disease in the elderly are similar to those of thyroid disease in the general population, although medications and iodine-containing compounds may play an increased role. Potential risks of subclinical hypothyroidism in the elderly include progression to overt hypothyroidism, cardiovascular effects, hyperlipidemia, and neurological and neuropsychiatric effects. Potential risks of subclinical hyperthyroidism in the elderly include progression to overt hyperthyroidism, cardiovascular effects (especially atrial fibrillation), and osteoporosis. Decisions to treat elderly subjects with subclinical thyroid disease should be based on a careful assessment of these risks in the individual patient.
Thyroid 1998 Sep
PMID:Subclinical thyroid disease in the elderly. 977 54

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 significance of subclinical hypothyroidism in regard to ensuing hyperlipidemia remains unclear. Because an unfavorable lipid profile would provide a possible explanation for the reported association of coronary-heart disease with this syndrome, we have evaluated the relationship of thyrotropin (TSH) with total cholesterol, low-density-lipoprotein (LDL) cholesterol, and triglycerides in patients with normal thyroid function (n = 4886) as well as subclinical (n = 1055) and manifest (n = 92) hypothyroidism. Serum concentrations of LDL cholesterol were similar in euthyroid persons (134+/-39 mg/dL) and in patients with subclinical hypothyroidism (137+/-40 mg/dL) but were higher (178+/-70 mg/dL, p < 0.01) in overt hypothyroidism. Within the group of subjects with subclinical hypothyroidism there was no apparent relationship between serum concentrations of TSH ranging from 4.0 to 49.0 microU/mL and concentrations of LDL cholesterol. Thus, there is no "threshold value" of TSH in these patients per se necessitating substitution therapy with thyroxine.
Thyroid 2000 Nov
PMID:Low-density lipoprotein cholesterol in subclinical hypothyroidism. 1112 26

Thyroid hormones (TH) are potent modulators of adaptive thermogenesis and can potentially contribute to development of obesity. The decrease of T(3) in association with reduction of calorie intake is centrally regulated via decreases in leptin and melanocortin concentrations and peripherally via a decrease in deiodinase activity, all aimed at protein and energy sparing. The use of TH in the treatment of obesity is hardly justified except in cases of elevated thyrotropin (TSH) with low/normal T(3) and T(4) and/or a low T(3) or T'(3)/T(4) or a high TSH/T(3) ratio. TH treatment with small doses of T(3) can also be exceptionally applied in obese patients resistant to dietary therapy who are taking beta-adrenergic blockers or with obesity developed after cessation of cigarette smoking and with hyperlipidemia and a concomitant high thryrotropin/T(3) ratio. Supplementation with Se(2+) and Zn(2+) may be tried along with more severe calorie restriction to prevent decline of T(3).
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PMID:Thyroid hormones in the pathogenesis and treatment of obesity. 1200 27

Hypothyroidism affects 4% to 10% of women, increasing with age. Symptoms, which are often nonspecific and subtle, can include: lethargy, mild weight gain, edema, cold intolerance, constipation, mental impairment, dry skin, depression, irregular menses, hoarseness, myalgias, hyperlipidemia, and bradycardia. TSH determination is usually warranted when some of these are present. Confirmation of diagnosis is based on laboratory tests, not symptoms. With Hashimoto's thyroiditis, the most common cause, the thyroid is usually firm and irregular to palpation. Screening is recommended by the American Thyroid Association, American Association of Clinical Endocrinologists and ACOG. Studies indicate that even slight hypothyroidism is associated with increased miscarriage, late fetal demise and lower IQ of offspring. Many believe all women intending conception or pregnancy should be screened. Most patients with even slightly elevated TSH should be treated, though controversy remains. Hypothyroidism is usually permanent, and treatment is life-long; postpartum thyroiditis may be transient. Levothyroxine is the standard treatment. Because of variable bioavailability of some levothyroxine preparations, designation of a specific high-quality brand is appropriate; TSH should be monitored to titrate the dose. The third-generation super-sensitive TSH is the most accurate test for both hypo- and hyperthyroidism. Because estrogen increases levels of thyroid binding globulin, women who are on HRT or OCs, or are pregnant, usually have total T4 levels above the reference range.
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PMID:Hypothyroidism and women's health. 1208 Dec 57

Few treatments for obesity exist and, whereas efficacious therapeutics for hyperlipidemia are available, further improvements are desirable. Thyroid hormone receptors (TRs) regulate both body weight and cholesterol levels. However, thyroid hormones also have deleterious effects, particularly on the heart. The TR beta subtype is involved in cholesterol lowering and possibly elevating metabolic rate, whereas TR alpha appears to be more important for control of heart rate (HR). In the current studies, we examined the effect of TR beta activation on metabolic rate and HR with either TR alpha 1-/- mice or the selective TR beta agonist KB-141 in mice, rats, and monkeys. 3,5,3'-triiodi-l-thyronine (T3) had a greater effect on increasing HR in WT than in TR alpha-/- mice (ED15 values of 34 and 469 nmol/kg/day, respectively). T3 increased metabolic rate [whole body oxygen consumption (MVO2)] in both WT and TR alpha-/- mice, but the effect in the TR alpha 1-/- mice at the highest dose was half that of the WT mice. Thus, stimulation of MVO2 is likely due to both TR alpha and -beta. T3 had equivalent potency for cholesterol reduction in WT and TR alpha-/- mice. KB-141 increased MVO2 with selectivities of 16.5- and 11.2-fold vs. HR in WT and TR alpha 1-/- mice, respectively. KB-141 also increased MVO2 with a 10-fold selectivity and lowered cholesterol with a 27-fold selectivity vs. HR in rats. In primates, KB-141 caused significant cholesterol, lipoprotein (a), and body-weight reduction (up to 7% after 1 wk) with no effect on HR. TR beta-selective agonists may constitute a previously uncharacterized class of drugs to treat obesity, hypercholesterolemia, and elevated lipoprotein (a).
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PMID:Selective thyroid hormone receptor-beta activation: a strategy for reduction of weight, cholesterol, and lipoprotein (a) with reduced cardiovascular liability. 1288 25

Subclinical and overt hypothyroidism are relatively common disorders in the general population. Thyroid hormone is known to play a role in regulating the synthesis, metabolism, and mobilization of lipids. In patients with overt hypothyroidism there is an increase in serum total cholesterol, low-density lipoprotein (LDL) cholesterol, apolipoprotein B, lipoprotein(a) levels, and possibly triglyceride levels. The effects of subclinical hypothyroidism on serum lipid values are less clear. The preponderance of evidence suggests that total cholesterol, LDL cholesterol, and possibly triglycerides are increased in patients with subclinical hypothyroidism, whereas high-density lipoprotein (HDL) cholesterol and Lp(a) remain unchanged. Most lipid abnormalities in patients with overt hypothyroidism will resolve with thyroid hormone replacement therapy. However, clinical trials to date have not shown a beneficial effect of thyroid hormone treatment on serum lipid levels in patients with subclinical hypothyroidism. The lipid-altering effects of thyroid hormone make it an appealing target for drug development. The development of specifically targeted thyroid hormone analogues that could potentially treat hyperlipidemia without causing systemic thyrotoxicosis is currently ongoing.
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PMID:Hypothyroidism and dyslipidemia: modern concepts and approaches. 1548 7


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