Establishing age and sex dependent upper reference limits for the plasma lipoprotein (a) in a Chinese health check-up population and according to its relative risk of primary myocardial infarction.

BACKGROUND: Though lipoprotein (a) (Lp (a)) has been considered as a risk factor for coronary artery disease, there is a lack of cutoff values of Lp (a) for Chinese Han ethnicity.

METHODS: We included 1 population for health check-ups. Lp (a) percentile distributions were analyzed and its cutoff for Chinese Han ethnicity was also proposed according to the its relative risk of myocardial infarction.

RESULTS: Lp (a) distributions differed between sexes, and were highly skewed towards low concentrations with a long tail towards the highest ones. The relative risks of elevated Lp (a) concentrations for myocardial infarction had an inflection in Chinese Han ethnic at the 8th decile, corresponding to 167 mg/l, where the risk was prone to be increased. In terms of Lp (a) median concentrations, per higher age quantile (5-y interval) was associated with a significant increase of 3.2 mg/l and females were on average 19.75 mg/l higher than males with a significant difference.

CONCLUSIONS: We proposed Lp (a) < 170 mg/l after rounding as cut-off values for Chinese Han ethnicity. Effects of age and sex on Lp (a) concentrations were also noted. Prospective validation of these cutoff values is critically important in Chinese Han ethnicity.