A process is disclosed for identifying free apo (a) in a human body fluid containing free apo (a) and a lipid-bound apo (a). The proposed process involves (a) separating the apo (a) bound to the lipids and subsequently identifying the free apo (a) by known methods; or (b) identifying the free apo (a) in an immune reaction with antibodies which react to the free, but not to bound, apo (a). This process provides a powerful tool for assessing disturbances in lipoprotein metabolism or a patient's atherogenic risk.
