Lability of HDL-cholesterol during serum storage

In many clinical and research situations it would be desirable to store, for extended periods, specimens on which measurements of high density lipoprotein cholesterol (HDL-C) levels were desired. To test the effects of storage on subsequent HDL-C levels, divided serum specimens from 46 subjects were frozen at -80 degrees C and analyzed at intervals throughout a 12-month period. A statistically significant increase in the HDL-C levels was found (P < 0.01). Thus, caution must be exercised in interpreting the results of HDL-C analysis done on specimens stored for prolonged periods even at -80 degrees C.