A drop of blood says it all
A blood test may seem very simple with the exception of the ‘prick’ but the actual diagnostic process is very complicated and requires specialized equipment; trained technicians; utmost care, caution and precision as most of the medical decisions are based on these results. Blood tests are the most common types of medical test and have a wide range of uses. For instance, a blood test can assess general state of health, rule out any infection, determine the function of certain organs such as the liver and kidneys, screen for certain genetic conditions etc.
Depending on the type of blood analysis, there could be restrictions for the intake of food or medicines which will be informed to the patient beforehand. For example testing fasting blood sugar is carried out while a patient is on a 12-hour fast. It is very important to follow the instruction that has been provided by the laboratory; else it may jeopardize the result of the test.
A blood sample is drawn from a blood vessel in the arm because the arm is a convenient part of the body that is easily accessible. The usual site for drawing the sample is the inside of the elbow or wrist, where the veins are close to the surface. Blood samples from children are often drawn from the back of the hand. Their skin may be numbed with a special spray or cream before the sample is taken.
A tourniquet is applied around the upper arm to squeeze the arm and temporarily slow down the flow of blood causing the vein to swell. This makes it easier for a phlebotomist to draw the blood sample.
Even before the blood is tested, it needs to be properly prepared for the analyzer. It might be subjected to centrifugation to separate the blood components, creating a serum or plasma sample. The blood analyzer device performs the required blood analysis and the test results are tabulated, verified and sent to the doctor.
There are more than 100 types of blood tests. The most common among them are as follows.
- Full blood count - checks for anaemia and other conditions which affect the blood cells.
- Kidney function.
- Liver function.
- Blood sugar (glucose) level.
- Blood clotting tests.
- Tests for inflammation.
- Blood cholesterol level.
- Immunology - such as checking for antibodies to certain viruses and germs (bacteria).
- Blood grouping.
- Thyroid function test.