The application describes methods for determining the particle number and/or molar mass of lipoprotein(a) subform(s) in a biological sample using enzyme linked immunosorbent assay (ELISA). The methods described herein significantly improve lipoprotein ELISA methods and devices capable of quantifying particle numbers and population mass of Lp(a) particles. This technology offers a method for the efficient and cost-effective measurement of specific Lp(a) in a rapid, low-cost format, rather than limited measurement of Lp(a) concentration in patient tissues. The ability to measure the particle number and/or molar mass of lipoprotein(a) subform(s) in a biological sample also provides a useful diagnostic tool for assessing cardiovascular risk in a subject.