The Food and Drug Administration has granted 510(k) clearance to Denka Seiken for a small dense low-density lipoprotein cholesterol (sdLDL-C) assay designed for use on any standard clinical chemistry analyzer. The assay quantifies sdLDL-C in serum and plasma samples in 10 minutes using a two-step process. The first step removes chylomicrons, very LDL, intermediate-density lipoprotein, large LDL, and high-density lipoprotein using a surfactant and sphingomyelinase. In the second step, a specific surfactant releases cholesterol only from the sdLDL-C particles for measurement by standard methods. Recent studies have shown that sdLDL-C predicted risk for incident coronary heart disease in individuals considered to be at low cardiovascular risk based on their LDL-C levels. These studies found that patients with a predominance of sdLDL-C have a three-fold increased risk of myocardial infarction (MI), while the relative risk is 4.5 for coronary artery disease and 7 for MI when sdLDL-C levels are greater than 100 mg/dL.