High-density lipoprotein subfractions measured in stored serum

Area of Science:

• Clinical Chemistry
• Lipid Metabolism
• Biochemistry

Background:

• Accurate measurement of high-density lipoprotein (HDL) subfractions is crucial for cardiovascular risk assessment.
• The stability of serum samples during storage can impact the reliability of HDL subfraction analysis.
• Different analytical methods may exhibit varying sensitivities to sample degradation.

Purpose of the Study:

• To compare the effects of serum freezing on HDL subfraction determination using two dual-precipitation methods (HM/DS and DS/DS) and ultracentrifugation.
• To evaluate the long-term stability of HDL subfractions in serum stored at -70°C.

Main Methods:

• Serum samples were stored at -70°C, -20°C, and 4°C.
• HDL subfractions were analyzed using heparin and manganese chloride/dextran sulfate (HM/DS) precipitation, dextran sulfate/dextran sulfate (DS/DS) precipitation, and ultracentrifugation.
• Cholesterol levels in total HDL and HDL3 subfractions were quantified.

Main Results:

• Storage at -70°C for up to 1 year showed no significant changes in HDL subfractions by the HM/DS method.
• Ultracentrifugation and the DS/DS method showed reduced HDL3-cholesterol after 1 month at -70°C.
• Serum stored at 4°C showed declining total HDL-cholesterol after 3 days, and at -20°C, both total and HDL3-cholesterol decreased after 1 month.

Conclusions:

• The HM/DS method is robust for determining HDL subfractions in serum and plasma stored at -70°C for up to one year.
• Serum storage conditions significantly affect the accuracy of HDL subfraction measurements, with -70°C being optimal for long-term preservation.
• The findings support the use of -70°C storage for reliable HDL subfraction analysis in clinical and research settings.