Table 1.

Types of lipoproteins in normal plasmaa

LipoproteinPhysiologic FunctionRelative Content (%)bApolipoproteinsc
TGChPlPr
ChylomicronTransport of dietary TG from gut to peripheral tissue and liver90532B-48, C-II, C-III, A-IV, E
VLDLTransport of endogenous TG from liver to peripheral tissues6020146B-100, C-II, C-III, E
IDLIntermediary of VLDL metabolism; usually present in small concentrations in plasma but elevated in kidney failure20402218B-100, E
LDLTransport of cholesterol from liver to peripheral tissues7502221B-100
HDLReverse transport of cholesterol from peripheral tissues to liver5252644A-I, A-II, A-IV
Lp(a)Unknown5452026apo(a), B-100
  • a apo, apolipoproteins; Ch, cholesterol; CKD, chronic kidney disease; IDL, intermediate-density lipoprotein; LCAT, lecithin:cholesterol acyltransferase; Lp(a), Lipoprotein(a); Pl, phospholipids; Pr, proteins; TG, triglycerides.

  • b Relative content of TG, Ch, Pl, and Pr in the various plasma lipoproteins. Data are based on individuals without CKD. Lp(a) contains additionally 4% carbohydrates.

  • c Only the major (apolipoproteins) or the ones with particular pathogenetic importance in uremia are presented for each lipoprotein. ApoB is a ligand for cellular receptors for lipoprotein uptake. ApoC-II is an activator of lipoprotein lipase that hydrolyzes triglycerides, whereas apoC-III is an inhibitor of the lipases. ApoE is a ligand for hepatic receptors that mediate the uptake of VLDL and IDL. ApoA-I is an activator of LCAT, which catalyzes the esterification and hence the reverse transport of cholesterol from periphery to liver. ApoA-IV is another activator of LCAT and lipoprotein lipase. ApoA-II is an activator of another lipase, the hepatic lipase, which also hydrolyzes TG from lipoproteins. Increased apoC-III levels, decreased lipoprotein lipase activity, and low apoA-I and apoA-II levels are hallmarks of uremic dyslipidemia, resulting in the accumulation of apoB-containing lipoproteins (e.g., IDL) and low levels of HDL cholesterol in plasma.