Background: Serum Lp(a) is routinely detected by mass concentration in clinical laboratory, but the results of which cannot be standardized. On the other hand, particle concentration detection has gained increasing popularity and facilitated the standardization of Lp(a) testing in clinical practice. This study aimed to compare the Lp(a) mass concentration and particle concentration between patients with stroke and healthy controls.
Methods: The participants admitted in the Third Hospital of Hebei Medical University between January 2021 and October 2021 were assigned to hemorrhagic stroke, cerebral infarction and healthy control group. Serum Lp(a) particle and mass concentration were detected by using the Shenzhen Mindray BS-2000I and Beckman AU5821 detection system, respectively. The primary study endpoint was the difference between Lp(a) mass concentration and particle concentration among the 3 groups.
Results: There was no statistically significant difference in age and gender among the 3 groups. Serum Lp(a) mass concentration [227.7 (113.1-447.1) mg/L vs. 117.1 (59.8-210.7) mg/L, P=0.001] and particle concentration [30.1 (12.9-72.3) nmol/L vs. 13.5 (6.8-29.9) nmol/L, P=0.001] in the cerebral infarction group were significantly higher than those in the healthy control group. The areas under the receiver operating characteristic (ROC) curve (AUC) of Lp(a) mass concentration and particle concentration for the diagnosis of cerebral infarction were 0.67 and 0.66, respectively, and the cut-off value was 181.1 mg/L and 15.6 nmol/L, respectively. There was no statistically significant difference in the efficacy of the two parameters for the diagnosis of cerebral infarction (Z=0.88, P=0.38). The conversion factors for the two concentrations were not significantly different between gender nor age subgroups, and decreased as mass concentrations increased. Compared with healthy control group, the positive rate of Lp(a) mass concentration (37.8% vs. 17.5%, P<0.01) and the positive rate of particle concentration (24.4% vs. 10.8%, P=0.005) were significantly increased in the cerebral infarction group.
Conclusions: The particle concentration detection of Lp(a) has significant clinical relevance in patients with ischemic stroke. The mass concentration test results may overestimate the actual serum Lp(a) content in stroke patients.
Keywords: Stroke; lipoprotein (a); mass concentration; particle concentration.