Biochemical correlates of lipoprotein(a) in a general adult population. Possible implications for cardiovascular risk assessment.

backgroundEvidence has been provided that lipoprotein(a) (Lp(a)) may be an important cardiovascular risk factor. Recognition of potential Lp(a) variability associated with common diseases, such as diabetes, chronic renal dysfunction, impaired liver function and acute/chronic inflammation, is important to optimize the clinical usefulness of this measurement.

methodsWe performed a retrospective analysis on our Laboratory Information System to retrieve results of fasting plasma glucose (FPG), creatinine, albumin, high sensitivity-C reactive protein (Hs-CRP) and Lp(a) tests, which were performed on all outpatients referred by general practitioners for routine blood testing during the last 5 years.

resultsCumulative results for all of the above parameters were retrieved for 1,195 adults. After stratifying Lp(a) results according to the respective threshold values of albumin, estimated glomerular filtration rate (e-GFR), FPG and Hs-CRP, a significant difference was observed only among subjects with increased Hs-CRP levels (170 mg/l vs. 125 mg/l; P < 0.001). The frequency of Lp(a) values > or =300 mg/l was greater in those with increased Hs-CRP levels (36 vs. 26%; P = 0.037)-but not in those with abnormal values of albumin, e-GFR or FPG-compared with their counterparts with normal values of these parameters. In multiple regression analysis, age (r = 0.112; P < 0.001), Hs-CRP (r = 0.102; P = 0.001) and e-GFR (r = 0.106; P = 0.003) were independent predictors of Lp(a).

conclusionsThe evaluation of laboratory markers of glucose homeostasis and liver function seems unnecessary when measuring Lp(a) for cardiovascular risk assessment. Conversely, Hs-CRP and probably GFR might be of clinical value to identify individuals whose serum Lp(a) levels can be transiently or chronically increased.