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Etiology and PathogenesisTop
Classification and etiology of severe hypertriglyceridemia:
1) Type V hyperlipoproteinemia: A combination of genetic, demographic, and clinical factors. Causes include obesity, diabetes mellitus, untreated hypothyroidism, HIV infection, lipodystrophy, anorexia, Cushing syndrome, sarcoidosis, systemic lupus erythematosus, alcohol consumption, and certain drugs (oral estrogen, glucocorticoids, protease inhibitors, hydrochlorothiazide, nonselective beta-blockers, retinoic acid, tamoxifen, raloxifene, cyclosporine [INN ciclosporin], sirolimus).
2) Familial chylomicronemia syndrome: Genetic (type I hyperlipoproteinemia according to the Fredrickson classification).
Type V hyperlipoproteinemia includes fasting chylomicronemia and high very low-density lipoprotein (VLDL) levels. The very rare type I hyperlipoproteinemia does not predispose to atherosclerosis, as chylomicrons are too large to penetrate the arterial wall. Nevertheless, there is still an increased risk of cardiovascular disease.
Clinical Features and DiagnosisTop
Clinical symptoms of severe hypertriglyceridemia with the presence of chylomicrons: Abdominal pain, acute pancreatitis.
Lipid profile: High TG levels, usually >11.3 mmol/L (1000 mg/dL). Low-density lipoprotein cholesterol (LDL-C) levels are low, whereas total cholesterol may be high, depending on the cholesterol content of chylomicrons and in type V hyperlipoproteinemia also of VLDL.
Chylomicronemia is usually an incidental diagnosis, which is prompted either by the occurrence of acute pancreatitis or by finding turbid plasma in a fasting patient or high serum TG levels in routine laboratory tests. The diagnosis is confirmed by identifying flotation of chylomicrons in the patient’s serum left overnight at 4 degrees Celsius. If chylomicrons are present, a creamy supernatant of varying thickness (depending on the concentration of chylomicrons) is observed. Under the fatty supernatant, the serum is transparent in patients with type I hyperlipoproteinemia and turbid in patients with type V hyperlipoproteinemia.
The main goal of treatment is prevention of acute pancreatitis.
1. A very low-fat diet (<10% of daily caloric requirements covered by fats), including both saturated and unsaturated fats. Additionally, reduce the intake of carbohydrates, particularly simple carbohydrates.
2. Abstinence from alcohol.
3. Fibrates (see Atherogenic Dyslipidemia).
4. Statins are used after lowering TG levels if the LDL-C target level is not reached.