Estimating the long-term effects of storage at -70 degrees C on cholesterol, triglyceride, and HDL-cholesterol measurements in stored sera.
We estimated the effects of long-term storage at -70 degrees C on serum total cholesterol, HDL-cholesterol, and triglycerides in specimens that had been stored for up to 7 years. These estimates were made using measurements in serial specimens collected from the placebo control group of the Air Force/Texas Coronary Atherosclerosis Prevention Study over a period of approximately 5 years. We compared the group means for pairs of serial specimens taken at 6- and 12-month intervals, assuming that (a) a negligible placebo effect occurred between the serial specimen pairs; (b) in the absence of storage effects, the variation in the group means would reflect only normal biological variation and would not materially affect the group means for the serial specimens; (c) any systematic changes in these group means would reflect storage-related changes; and (d) storage-related changes are cumulative, i.e., the overall changes for a given storage period are the sum of the changes during previous storage periods. We observed average decreases of 2.0% per year for total cholesterol over 7 years and 2.8% per year in triglycerides for the first 5 years. HDL-cholesterol decreased by 1.3% per year, but this change was not statistically significant. This approach may be useful for estimating storage-related changes for studies in specimens stored for a period of years and for which stability data may not be available.
Shih
W J
WJ
Merck Research Laboratories, Rahway, NJ 07065, USA.
Bachorik
P S
PS
Haga
J A
JA
Myers
G L
GL
Stein
E A
EA
D001800:Blood Specimen Collection; D002784:Cholesterol / Q000097:blood*; D008076:Cholesterol, HDL / Q000097:blood*; D006801:Humans; D013997:Time Factors; D014280:Triglycerides / Q000097:blood*
D008076:Cholesterol, HDL; D014280:Triglycerides; D002784:Cholesterol