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Dyslipidemia
Published in Gia Merlo, Kathy Berra, Lifestyle Nursing, 2023
Susan Halli-Demeter, Lynne T. Braun
Some individuals have a genetic predisposition for familial hypercholesterolemia (FH) (Type IIa hyperlipidemia), familial combined hyperlipidemia (Type IIb hyperlipidemia), familial dysbetalipoproteinemia (Type III hyperlipidemia), and familial hypertriglyceridemia (Type IV hyperlipidemia). Genetic testing can assist in confirming the diagnosis of FH. Other conditions, such as thyroid disease, diabetes, impaired fasting glucose, chronic kidney disease, metabolic syndrome, polycystic ovarian syndrome, obesity, human immunodeficiency virus (HIV), anorexia nervosa, autoimmune disorders (lupus and Cushing’s disease), liver disease (cirrhosis and fatty liver disease), pregnancy, and conditions that increase female hormones, can affect the lipid profile, and must be evaluated and treated. Medications can also adversely affect the lipid panel; these include corticosteroids, anabolic steroids, steroid hormones, beta blockers, amiodarone, loop and thiazide diuretics, Sodium-glucose Cotransporter-2 (SGLT2) inhibitors, antiviral therapy, immunosuppressants, antipsychotics, anticonvulsants, retinoids, and growth hormone. Environmental factors that can contribute to dyslipidemia include a high saturated/trans-fat and/or high sugar diet, physical inactivity, physical stress, excessive alcohol, and tobacco use.
Atherosclerosis
Published in George Feuer, Felix A. de la Iglesia, Molecular Biochemistry of Human Disease, 2020
George Feuer, Felix A. de la Iglesia
In familial dysbetalipoproteinemia or Type III lipoprotein disorder, remnant lipopoteins accumulate in plasma. This is due to substitution of cysteine for arginine in apoE.479 Plasma concentration of cholesterol and triglycerides are increased; the plasma appears turbid. The electrophoretogram shows an elevated β-lipoprotein band extended diffusely into the pre-β-lipoprotein zone. Since apoE is essential for the efficient clearance of chylomicrons and VLDL remnants from the plasma,172 affected individuals have highly elevated levels of these lipoproteins in their bloodstream. The abnormality of the β-lipoprotein band is related to an abnormal triglyceride content many time greater than that found in normal β-lipoproteins. Postheparin lipoprotein lipase activity is low. Xanthomas and other clinical signs of atherosclerosis are present.253 Low cholesterol and unsaturated fatty acid diets are usually advised.
The Diagnosis and Management of Lipoprotein Disorders
Published in Jack L. Leahy, Nathaniel G. Clark, William T. Cefalu, Medical Management of Diabetes Mellitus, 2000
Ernst J. Schaefer, Leo J. Seman
A much rarer form of combined elevations of cholesterol and triglyceride is familial dysbetalipoproteinemia (type III hyperlipoproteinemia) in which affected subjects have accumulations of chylomicron remnants and VLDL in the fasting state. These patients usually are homozygous for a mutation in the apo E protein (apo E-II/II phenotype) or rarely have apo E deficiency, resulting in defective hepatic clearance of chylomicron and VLDL remnants as well as increased VLDL production. They may also have tuboeruptive and planar xanthomas. Precise diagnosis requires quantitation of lipoprotein cholesterol values following ultracentrifugation and apo E genotyping. Treatment consists of diet, niacin, gemfibrozil, or an HMGCoA reductase inhibitor. These patients are also very responsive to gemfibrozil or niacin. Patients with both familial combined hyperlipidemia and familial dysbetalipoproteinemia often have obesity, glucose intolerance, and hyperuricemia.
The clinical and laboratory investigation of dysbetalipoproteinemia
Published in Critical Reviews in Clinical Laboratory Sciences, 2020
Christopher S. Boot, Ahai Luvai, Robert D. G. Neely
Familial dysbetalipoproteinemia (FDBL) has several synonyms including type III hyperlipoproteinemia, floating beta disease, broad beta disease and remnant hyperlipidemia. The fact that the precise definition is not universally agreed upon influences the prevalence estimates reported in different studies. However, the presence of mixed hyperlipidemia with markedly increased chylomicron remnants and very low-density lipoprotein (VLDL) remnants (cholesterol-enriched VLDL) together with pathogenic mutations in the apolipoprotein E (apo E) gene are reliable hallmarks of the disease [1–3]. Using this definition, the prevalence of this form of hyperlipidemia is probably only about 1 in 5000–10,000 (although estimates vary markedly) whereas the frequency of the apo E2/2 genotype is about 1 in 100 in the general population. It is therefore apparent that additional metabolic factors that provoke an increased concentration of either chylomicron or VLDL remnants must also be present for hyperlipidemia to ensue [4]. Such factors include obesity, diabetes, untreated hypothyroidism, excessive alcohol use, medications or other genetic disorders. FDBL carries an increased risk for the future development of premature cardiac and diffuse vascular disease, necessitating early precise diagnosis to enable effective lifestyle and lipid modifying treatment and assessment of other family members who may be affected [5–7]. The clinical presentation, inheritance and typical laboratory findings of FDBL/type III hyperlipoproteinemia are compared to the other Frederickson classifications of hyperlipoproteinemia in Table 1.
Recent developments in pharmacotherapy for hypertriglyceridemia: what’s the current state of the art?
Published in Expert Opinion on Pharmacotherapy, 2020
Matilda Florentin, Michael S Kostapanos, Panagiotis Anagnostis, George Liamis
Hypertriglyceridemia may be secondary in the setting of several disorders, such as insulin resistance or frank diabetes mellitus (DM), obesity, alcohol abuse, chronic kidney disease and several endocrine diseases (e.g. hypothyroidism, Cushing’s disease), or occurs in the context of genetic disorders. Mild to moderate hypertriglyceridemia may be a feature of familial dysbetalipoproteinemia, familial combined hyperlipidemia (FCH) or familial hypertriglyceridemia (FHTG), while extremely high TG levels are a feature of familial chylomicronemia syndrome (FCS) or apolipoprotein (apo) C-II deficiency [18,19]. Familial dysbetalipoproteinemia and FCH are clearly associated with increased coronary heart disease (CHD) risk, whereas this risk is lower in patients with FHTG [17,19]. On the other hand, individuals with FCS or apoC-II deficiency have high chances to suffer from pancreatitis rather than CHD [17,19].
Lipoprotein(a) in atherosclerosis: from pathophysiology to clinical relevance and treatment options
Published in Annals of Medicine, 2020
Andreja Rehberger Likozar, Mark Zavrtanik, Miran Šebeštjen
Higher plasma levels of Lp(a) have been linked to increased risk of CVD, and especially of MI, stroke, and aortic valve stenosis due to calcification [46]. This risk is usually increased two-fold for patients who have mostly small apo(a) isoforms (which are smaller due to the lower levels of KIV subtype 2), as this leads to rapid production of, and thus higher levels of, Lp(a). Also, patients who have FH have greater risk of developing CVD [62]. According to the 2019 European Society of Cardiology/European Atherosclerosis Society guidelines, Lp(a) measurements should be considered at least once in the lifetime of each adult, to identify those with very high inherited Lp(a) levels (>180 mg/dL; >430 nmol/L). These people might have a lifetime risk of atherosclerotic CVD that is equivalent to that associated with heterozygous FH [10]. The 2016, the Canadian Cardiovascular Society guidelines for the management of dyslipidemia suggested that Lp(a) might aid risk assessment in subjects at intermediate Framingham risk or with a family history of premature CAD. Particular attention should be given to individuals with Lp(a) levels >30 mg/dL, for whom CVD risk is increased by approximately two-fold [63]. The 2018 American College of Cardiology/American Heart Association guidelines on blood cholesterol defined Lp(a) ≥50 mg/dL, or ≥125 nmol/L, as a risk-enhancing factor; according to their guidelines, this is a relative indication for its measurement with a family history of premature CVD. HEART UK recommended that Lp(a) is only measured in specific cohorts, rather than in all adults, to identify those with a lower Lp(a) threshold than 430 nmol/L. They recommended the management of Lp(a)-associated risk in those with Lp(a) levels >90 nmol/L. They also recommend measuring Lp(a) levels in patients with personal or family history of premature atherosclerotic CVD (<60 years of age), in those with FH or other genetic dyslipidemias (e.g. familial combined hyperlipidaemia, familial dysbetalipoproteinemia, familial hypertriglyceridaemia), in those whose first-degree relative has Lp(a) levels >200 nmol/L, in those who have calcific aortic valve stenosis, and in those with borderline increased (but <15%) 10-year risk of CV events [13]. A single measurement of serum Lp(a) appears sufficient for cardiovascular risk assessment [13, 63], as for most patients repeat measurement is only indicated if a secondary cause is suspected (e.g. chronic kidney disease, nephrotic proteinuria, hypothyroidism, liver disease) or if therapeutic measures to lower levels have been introduced [13]. Hyperlipoproteinemia(a) should be considered as a hereditary and quantitative risk factor that can be mitigated by controlling the CV risk factors, and in particular by reduction of Lp(a) levels by treatment [64].