Lipoprotein(a) is not elevated in non-diabetic microalbuminuric subjects. A longitudinal study of lipoprotein(a) concentrations and apolipoprotein(a) size isoforms.

Microalbuminuric non-diabetic subjects have an increased risk of cardiovascular disease which is not explained by standard risk factors. In diabetic patients, microalbuminuria is associated with increased lipoprotein(a) concentrations. We have determined lipoprotein(a) concentrations and duplicate measures of albumin excretion rate, on two occasions separated by around 3 years, in 125 Europid subjects aged 40-75 years without hypertension or glucose intolerance and in 49 offspring aged 15-40 years. The apolipoprotein(a) isoform size, the major genetic determinant of lipoprotein(a) concentration, was also determined. There were no differences in lipoprotein(a) concentration between the 42 subjects who were microalbuminuric on either or both samples at screening (median 9.4 mg/dl, 20th and 80th percentiles 2.6 and 46.3 mg/dl) and the 79 who had been normoalbuminuric at both collections (median 10.9 mg/dl, 20th and 80th percentiles 2.9 and 53.0 mg/dl; P = 0.58). Lipoprotein(a) concentrations were not significantly different between subjects with or without microalbuminuria at recell (P = 0.55) or between those with or without microalbuminuria classified by mean albumin excretion rate in either collection (P = 0.24 and P = 0.73, respectively). There were no significant relationships between albumin excretion rate as a continuous variable and lipoprotein(a) concentration, or between changes in the two variables over 3 years. The microalbuminuric and normoalbuminuric subjects had similar distributions of size isoforms. There were also no differences in lipoprotein(a) concentration or isoform distribution between offspring of microalbuminuric and of normoalbuminuric subjects. In conclusion, we found no evidence that microalbuminuric subjects with normal blood pressure and normal glucose tolerance have elevated concentrations of lipoprotein(a) to explain their increased cardiovascular risk.