Lipoprotein measurements are diagnostic indicators for hyperlipidemia and hypolipidemia. Hyperlipidemia is classified as types I, IIa, IIb, III, IV, and V. Lipids are fatty substances made up of cholesterol, cholesterol esters (liquid compounds), triglycerides, nonesterized fatty acids, and phospholipids. Lipoproteins are unique plasma proteins that transport otherwise insoluble lipids. They are categorized as chylomicrons, β-lipoproteins (low-density lipoproteins [LDLs]), pre-β-lipoproteins (very-low-density lipoproteins [VLDLs]), and α-lipoproteins (high-density lipoproteins [HDLs]). Apolipoprotein A is mainly composed of HDL, chylomicrons, and VLDL. Apolipoprotein B is the main component of LDL. Lipids provide energy for metabolism, serve as precursors of steroid hormones (adrenals, ovaries, testes) and bile acids, and play an important role in cell membrane development. A lipid profile usually includes cholesterol, triglycerides, LDL, and HDL levels.
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