Apolipoprotein A1 (APOA / APO-A1)

Clinical definition of the Apolipoprotein A-1 test
Apolipoproteins are proteins that bind to lipids to form lipoproteins. They help to transport the lipids through the lymphatic and circulatory systems. Their synthesis in the liver is controlled by a host of factors, including dietary composition, hormones (insulin, glucagon, thyroxin, estrogens, and androgens), alcohol intake, and various drugs (statins, niacin, and fibric acids).
Apolipoprotein A-I is a relatively abundant plasma protein and is encoded by the APOA1 gene. It is the major protein component of HDL (High-density lipoprotein) or 'good cholesterol' and has a specific role in lipid metabolism and anticlotting effect of the body. Defects in the gene encoding it are associated with HDL deficiencies, including Tangier disease, and with systemic non-neuropathic amyloidosis.

Why is the Apolipoprotein A-1 test done?
The Apolipoprotein A-1 blood test is used to evaluate survival rate or risk factors for individuals with past heart attacks, peripheral vascular diseases and hyperlipidemia. Apo A-I levels may also be ordered to help diagnose conditions that cause Apo A-I deficiencies and may be used to monitor the effectiveness of lifestyle changes and lipid treatments.
Apo A-1 recycles cholesterol from the tissues back to the liver for further processing. It keeps the arteries clear of plaque-forming cholesterol. Exciting new research suggests that Apolipoprotein A-1 blood levels may be a better indicator of atherosclerosis and coronary artery disease (CAD) than the traditional cholesterol tests for high-density lipoprotein (HDL), low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL).

What are the common signs/symptoms when the Apolipoprotein A-1 test is done?

  • Shortness of breath
  • Headaches
  • Pain, fullness, and/or squeezing sensation of the chest
  • Jaw pain, toothache, headache
  • Nausea, vomiting, and/or general epigastric (upper middle abdomen) discomfort
  • Sweating
  • Heartburn and/or indigestion
  • Arm pain (more commonly the left arm, but may be either arm)
  • Upper back pain
  • General malaise (vague feeling of illness)

Who should do the Apolipoprotein A-1 test (Target population)?
People who have a personal or family history of heart disease, CAD and/or hyperlipidemia.

What should I do before the Apolipoprotein A-1 test?

Specimen type

Specimen collection procedure

Preparatory instructions during specimen collection*

Serum (Blood Sample)

Venipuncture - Collection of blood from a vein, usually from the arm.

Fasting Required.

Fasting samples have to be collected after a minimum 12-14 hour overnight fasting status.

Clear fluids like water is allowed during this period. Refrain from consumption of early morning beverages like tea, coffee and milk until specimen collection is completed.

In case of diabetics on oral or injectable hypoglycemic agents, consult your physician about continuing with these medications prior to specimen collection.

*Subjects suffering from any illness or on oral or injectable medications are advised to consult their physician prior to requesting any tests or procedures.

How do I interpret my Apolipoprotein A-1 test results?

Gender

Reference Range

Male:

94-178 mg/dL

Female:

101-199 mg/dL 

Inference:  High levels of Apo-I is usually not a problem, but decreased levels indicate low levels of HDL and hence a decreased clearance of excess cholesterol from the body. Low levels of Apo A-I, along with high concentrations of Apo B, are associated with an increased risk of coronary artery disease.
‘*A Reference range is a set of values which helps the healthcare professional to interpret a medical test. It may vary with age, gender, and other factors. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’

Diseases/conditions related to the Apolipoprotein A-1 test

  • Coronary artery disease (CAD)
  • Atherosclerosis
  • Cardiac arrest
  • Peripheral vascular diseases
  • Hyperlipidemia
  • Tangier disease
  • Systemic non-neuropathic amyloidosis

Other tests related to the Apolipoprotein A-1 test

  • HDL
  • LDL
  • Lipid Profile
  • Cholesterol
  • Apo B
  • Lp(a)

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Apolipoprotein A1/B

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