Blood tests include various laboratory tests that are performed using a sample of your blood. Your doctor usually orders a blood test as a routine check-up to assess your general state of wellbeing. These diagnostic tests may be ordered by your physician for the following reasons:
- Evaluate how well your organs, such as the kidneys, liver and thyroid are working
- Diagnose various diseases and conditions
- Assess if certain medicines are working
- Check for the presence of infections
- Detect certain genetic disorders
Most blood tests do not require any specific preparation, but some may require fasting from food or certain medicines. During a blood test, a sample of blood is drawn from a vein in your arm using a needle or through a finger prick. The blood may be used whole or may be separated in a centrifuge machine to analyse only part of the blood called serum, for different substances. Some common blood tests include:
- Complete blood count or CBC: Measures the concentration, number, percentage and normal structure and functioning of red blood cells, white blood cells, platelets and haemoglobin (iron protein in red blood cells) in your blood, and is thus ordered as a routine check-up to detect infections, anaemia, blood clotting problems and other blood-related abnormalities.
- Blood chemistry tests: Measures different chemicals present in the blood and is ordered to provide information about the normal functioning of your bones, muscles and organs such as liver and kidneys. The test includes the blood glucose test, calcium test, electrolytes and kidney function tests.
- Blood enzyme tests: Measures the level and activity of certain enzymes, which can help diagnose heart attack.
- Lipoprotein panel test: Measures the level of total cholesterol, bad and good cholesterol (LDL and HDL) and triglycerides in your blood. The test helps in assessing your risk of coronary heart disease (CHD).
- Blood clotting tests: Measures how fast your blood clots. The test is useful in diagnosing bleeding disorders.