Lipoprotein(a)

Lipoprotein (a) (Lp(a)) is a fat-protein complex related to LDL (low-density lipoprotein), that is, ” bad cholesterol,” and is a major component of LDL cholesterol. It also bears a strong resemblance to the structure of plasminogen. Lipoprotein (a) is produced in the liver. It contains the apolipoproteins apo(a) and apo B-100, which are covalently linked by a disulfide bridge. How much lipoprotein (a) the liver produces is determined by the apo(a) gene, and the amount remains relatively constant throughout life: since the lipoprotein (a) level in men increases only insignificantly with age, laboratory testing of this level is required only once in a lifetime. In women, on the other hand, the test should be performed both before and after menopause, since the lipoprotein (a) level increases significantly during menopause. In blood clotting, lipoprotein (a) plays the role of a counterpart of plasminogen – the inactive enzyme precursor of plasmin – which dissolves fibrin clots (blood clots). Lipoprotein (a) displaces plasminogen from its binding sites on endothelial cells (vessel walls) and fibrin, so that fibrinolysis (fibrin cleavage) is inhibited and cholesterol-containing lipoprotein(a) can deposit on vessel walls. Lipoprotein (a) thus has both a thrombogenic – thrombus-promoting – and an atherosclerosis-promoting (arteriosclerosis-promoting) effect. Lipoprotein (a) thus represents an independent risk factor for the development of atherosclerosis (hardening of the arteries) and coronary heart disease (disease of the coronary vessels), with the possible consequence of myocardial infarction (heart attack) or apoplexy (stroke). The ESC guideline recommends Lp(a) measurement at least once in a lifetime.

The procedure

The concentration of lipoprotein (a) can be determined from your blood serum using a laboratory diagnostic test. Material needed

  • Blood serum
  • Or plasma

Normal values for lipoprotein (a)

  • 0-30 mg/dl

Indications

Lipoprotein (a) determination is recommended for the following health risks or diseases:

  • Hyperlipidemia (dyslipidemia) – especially in the presence of an unfavorable LDL/HDL ratio.
  • Atherosclerosis or secondary disease(s) in the family history.
  • Suspected coronary artery disease (disease of the coronary arteries) without identifiable risk.
  • Screening to determine the individual, genetic risk, that is, early detection of atherosclerosis risk.

Interpretation

Interpretation of increased values

  • Acute-phase conditions (e.g., infections, myocardial infarction/heart attack).
  • Nephrotic syndrome – clinical symptom complex associated with proteinuria (protein excretion in urine):
    • Hypo- and dysproteinemia (deviations in the ratio of protein bodies of blood plasma).
    • Hyperlipidemia (lipid metabolism disorder).
    • Hypocalcemia (calcium deficiency)
    • Accelerated ESR (erythrocyte sedimentation rate).
    • Edema formation (water retention)
  • Renal insufficiency (kidney weakness; increase in the concentration of urinary substances (creatinine, urea, uric acid) in the blood).
  • Uremics under dialysis – patients with “urinary intoxication”, that is, an increase in urinary substances in the blood serum under treatment by blood washing.
  • Patients with poorly adjusted diabetes mellitus.
  • Hypothyroidism (underactive thyroid gland)

Interpretation of lowered values

Further notes

  • If lipoprotein (a) is above 30 mg/dl, your risk of cardiovascular disease increases 2.5-fold. If elevated LDL cholesterol levels above 3.9 mmol/L (150 mg/dl) are found at the same time, the risk of cardiovascular disease is increased 6-fold.
  • Southern Europeans are more frequently affected by a genetic burden of the LPA gene than Northern Europeans (Lp(a) levels: median 10.9 mg/dl; 4.9 mg/dl).
  • Lipoprotein (a) is an independent predictor of coronary artery disease (CAD) severity for individuals with type 2 diabetes.