Lipoprotein(a) (Lp(a)) is a lipoprotein subclass. Lp(a) is a risk factor for atherosclerotic diseases such as coronary heart disease and stroke.
The physiological function of Lp(a) is still unknown. A function within the coagulation system seems plausible. Other functions have been related to recruitment of inflammatory cells through interaction with Mac-1 integrin, angiogenesis, and wound healing.
Studies whown that high Lp(a) in blood is a risk factor for coronary heart disease (CHD), cerebrovascular disease (CVD), atherosclerosis, thrombosis, and stroke. Commonly prescribed lipid-reducing drugs have little or no effect on Lp(a) concentration. Niacin and aspirin are two safe, easily available and inexpensive drugs known to significantly reduce the levels of Lp(a) in some individuals with high Lp(a).
Its concentration is measured by means of analysis of a blood sample drawn from the vein in the arm.
Purpose of the test
High Lp(a) predicts risk of early atherosclerosis similar to high LDL, but in advanced atherosclerosis, Lp(a) is an independent risk factor not dependent on LDL. Lp(a) then indicates a coagulant risk of plaque thrombosis. Apo(a) contains domains that are very similar to plasminogen (PLG). Lp(a) accumulates in the vessel wall and inhibits binding of PLG to the cell surface, reducing plasmin generation which increases clotting. This inhibition of PLG by Lp(a) also promotes proliferation of smooth muscle cells. These unique features of Lp(a) suggest Lp(a) causes generation of clots and atherosclerosis.
Reference range values
Lp(a) concentrations widely vary between individuals, from < 2 to > 2000 mg/L. This range of concentrations is observed in all populations studied so far. The mean and median concentrations between different world populations show distinct particularities, the main being the two- to threefold higher Lp(a) plasma concentration of populations of African descent compared to Asian, Oceanic, or European populations.
Thus the threshold below values are applicable only to individuals of European descent, if at all.
Desirable: < 14 mg/dL (< 35 nmol/l)
Borderline risk: 14 - 30 mg/dL (35 - 75 nmol/l)
High risk: 31 - 50 mg/dL (75 - 125 nmol/l)
Very high risk: > 50 mg/dL (> 125 nmol/l)
Fish oil supplements may be helpful to lower the levels of Lp-a.
Fibrates such as benzafibrate or gemfibrozil have significantly lowered Lp-a in some individuals.
Regular consumption of alcohol leads to significant decline in plasma levels of Lp-a.
High levels of Apo AI HDL cholesterol are protective against atherogenic potential of Lp-a.