Effect of storage at 4 degrees C and -20 degrees C on lipid, lipoprotein, and apolipoprotein concentrations.
We have investigated the effects on lipid, apolipoprotein, and lipoprotein measurements of storing unfractionated serum at 4 degrees C for 10 days and at -20 degrees C for 10 days or 3 months. Total serum concentrations of lipids were stable, although apolipoprotein B showed a 5.3% increase after 3 months at -20 degrees C (P < 0.001). Increases in low-density (LDL) and high-density lipoprotein (HDL) triglyceride and very-low-density lipoprotein (VLDL) esterified cholesterol concentrations and decreases in free cholesterol concentrations in LDL and HDL after storage of serum for 10 days at 4 degrees C were verified by fractionation of lipoproteins by sequential flotation ultracentrifugation. Ten days' storage of serum at -20 degrees C resulted in increases in VLDL triglyceride and phospholipid concentrations, with decreases in HDL concentrations in triglycerides and phospholipids; changes were more extensive after 3 months at -20 degrees C. We conclude that ultracentrifugation of serum for lipoprotein analysis should be performed as soon as possible after collection.
Evans
K
K
Department of Clinical Biochemistry and Metabolic Medicine, University of Newcastle upon Tyne, Medical School, UK.
Mitcheson
J
J
Laker
M F
MF
D001053:Apolipoproteins / Q000097:blood*; D002784:Cholesterol / Q000097:blood; D004355:Drug Stability; D005260:Female; D005615:Freezing; D006801:Humans; D008055:Lipids / Q000097:blood*; D008074:Lipoproteins / Q000097:blood*; D008075:Lipoproteins, HDL / Q000097:blood; D053419:Lipoproteins, IDL; D008079:Lipoproteins, VLDL / Q000097:blood; D008297:Male; D014280:Triglycerides / Q000097:blood
D001053:Apolipoproteins; D008055:Lipids; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D053419:Lipoproteins, IDL; D008079:Lipoproteins, VLDL; D014280:Triglycerides; D002784:Cholesterol