Apolipoprotein A1 is a plasma protein that is a major component of high-density lipoproteins (HDL), also known as "good cholesterol." It facilitates the removal of cholesterol from vessel walls, transporting it to the liver for excretion. Apo A1 activates the enzyme lecithin-cholesterol acyltransferase (LCAT), which catalyzes the esterification of cholesterol and enhances lipid transport within lipoproteins.
There are two forms of Apo A:
- Apolipoprotein A1 (Apo A1)
- Apolipoprotein A2 (Apo A2) (its level is three times lower than Apo A1).
Apo A1 is a critical marker for assessing the risk of cardiovascular diseases (CVD) and atherosclerosi
- Sample: Venous blood.
- Fasting for 12 hours (minimum 8 hours, not exceeding 14 hours) before the test.
- Avoid physical and emotional stress.
- Refrain from smoking for 30 minutes before the test.
- Assessment of risk for ischemic heart disease.
- Diagnosis of hereditary lipid metabolism disorders.
- Evaluation of cardiovascular disease risk and complications.
- Calculation of the Apo B/Apo A1 ratio as an alternative or supplement to cardiovascular risk assessment.
- Monitoring after the detection of high cholesterol.
- Early-onset cardiovascular disease in patients or their relatives.
- Suspected hereditary Apo A deficiency or hyperlipidemia due to Apo A1 deficiency.
- Evaluation of lipid targets in patients on lipid-lowering therapy (e.g., statins) or with high cardiovascular risk.
Risk factors include:
- Age: >45 years for men, >55 years for women.
- High blood pressure (>140/90 mmHg).
- Family history of high cholesterol or cardiovascular diseases (men <55 years, women <65 years).
- Diabetes and obesity.
- Alcohol consumption and diets rich in animal fats.
Increased Apo A1 Levels:
- Hereditary hyperalphalipoproteinemia.
- Familial deficiency of cholesterol ester transport proteins.
- Acute myocardial infarction (recovery phase).
- Liver diseases (e.g., primary biliary cirrhosis).
- Alcohol consumption.
- Weight loss or intense aerobic exercise.
- Pregnancy (testing recommended ≥6 weeks postpartum).
- Medications: carbamazepine, fibrates, statins, estrogens, oral contraceptives, phenobarbital, phenytoin, prednisolone.
Decreased Apo A1 Levels:
- Tangier disease (familial hypoalphalipoproteinemia).
- Genetic variants of Apo A1.
- Familial LCAT enzyme deficiency.
- Coronary artery disease and cerebrovascular diseases.
- Triglyceridemia and high atherosclerosis risk.
- Hepatocellular disorders, cholestasis.
- Nephrotic syndrome or chronic kidney failure.
- Uncontrolled diabetes.
- Infectious diseases or sepsis.
- Cancer and chronic inflammatory conditions.
- Chronic pancreatitis.
- Total parenteral nutrition.
- Severe liver diseases.
- Smoking.
- Medications: diuretics, androgens, progestins, beta-blockers.