Atherosclerosis 152 (2000) 259
Letter to the Editor
www.elsevier.com/locate/atherosclerosis
Lipoprotein (a) and chronic obstructive pulmonary disease
Dear Sir,
We read with great interest the paper by Basili et al. [1] assessing the lipoprotein (a) (Lp(a)) serum levels in patients affected by chronic obstructive pulmonary dis-ease (COPD). The authors found significantly lower serum Lp(a) and Apolipoprotein B-100 levels in COPD patients than in healthy subjects. However, they state that the serum was stored at −40°C. Furthermore, they mention that the patients were studied between March 1997 and January 1999, which suggests that the serum was stored for a long period. Many studies have shown that measurement of Lp(a) in old frozen samples is likely to result in a preferential decrease and false lower Lp(a) concentrations in patient groups compared with control groups, especially when the temperature of storage is not −80°C [2 – 4]. Therefore, we believe that the differences observed in the study of Basili et al. may be artificial. Moreover, the authors state as a possible explanation a moderate liver failure. However, this cannot be substantiated by their findings, as no other
laboratory tests were performed.
References
[1] Basili S, Ferromi P, Vieri M, et al. Lipoprotein(a) serum levels in patients affected by chronic obstructive pulmonary disease. Atherosclerosis 1999;147:249 – 52.
[2] Kronenberg F, Trenkwalder E, Dieplinger H, Utermann G. Lipo-protein(a) in stored plasma samples and the ravages of time: why epidemiological studies might fail. Arterioscler Thromb Vasc Biol 1996;16:1568 – 72.
[3] Kronenberg F, Lobentanz EM, Konig P, Utermann G, Dieplinger H. Effect of sample storage on the measurement of lipoprotein(a), apolipoproteins B and A-IV, total and high density lipoprotein cholesterol and triglycerides. J Lipid Res 1994;35:1318 – 28. [4] Sgoutas DS, Tuten T. Effect of freezing and thawing of serum on
the immunoassay of lipoprotein(a). Clin Chem 1992;38:1873 – 7.
D.N. Kiortsis, A. Evangelou, M.S. Elisaf
Department of Physiology and Internal Medicine,
Medical School Uni6ersity of Ioannina, 45110 Ioannina,
Greece
