Apolipoprotein A-1 (Apo A1)
ApoA-I is a protein that is produced by the liver and intestines. It provides structure to the HDL molecule (the "good" cholesterol) and activates enzymes necessary for this process to take place.
This test itself measures the number of ApoA-I proteins still available to form HDL. Lower levels of Apo-A-I suggest an increased risk of developing cardiovascular disease.
Resources: Boston Heart Diagnostics