Combined hyperlipidemia

In medicine, combined hyperlipidemia (or -aemia) is a commonly occurring form of hypercholesterolemia(elevated cholesterollevels) characterised by increased LDLand triglycerideconcentrations, often accompanied by decreased HDL. On lipoprotein electrophoresis(a test now rarely performed) is shows as a hyperlipoproteinemia type IIB.

The elevated triglyceridelevels (>5 mmol/l) are generally due to an increase in VLDL(very low density lipoprotein), a class of lipoproteinthat is prone to cause atherosclerosis.

There are roughly two forms of this lipiddisorder:

• Familiar combined hyperlipidemia (FCH) is the familiar occurrence of this disorder, probably caused by polymorphismsin molecules and enzymesthat participate in lipoproteinmetabolism, such as ApoCII and ApoCIII and CETP (cholesterylester transferring protein).
• Acquired combined hyperlipidemia is extremely common in patients who suffer from other diseases from the metabolic syndrome("syndrome X", incorporating diabetes mellitustype II, hypertension, central obesityand CH). Excessive free fatty acidproduction by various tissues leads to increased VLDLsynthesis by the liver. Initially, most VLDL is converted into LDLuntil this mechanism is saturated, after which VLDL levels elevate.

Both conditions are treated with fibratedrugs, which act on the peroxisome proliferator-activated receptors(PPARs), specifically PPARα, to decrease free fatty acid production. Statindrugs, especially the synthetic statins (atorvastatinand rosuvastatin) can decrease LDL levels by increasing hepatic reuptake of LDL due to increased LDL-receptor expression.

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It uses material from the http://en.wikipedia.org/wiki/Combined+hyperlipidemia Wikipedia article Combined hyperlipidemia.