What are blood tests?

Blood tests are performed by taking a blood sample from the person. It is an essential part of a routine physical examination to know about blood type or help doctors assess, diagnose, and treat various medical conditions.

Why are blood tests required?

Doctors prescribe blood tests as per the medical condition and to know:

The entire picture of a person’s health.
The health of certain organs, like the liver, kidneys, heart, thyroid, etc.
Presence of some genetic conditions.
Any infection.
Possibility of anaemia, variation in blood, or low haemoglobin.
Presence of diseases like diabetes, cancer, or HIV/AIDS.
Progress of any treatment or medicine.

About Blood Test

We usually know common blood tests like CBC, KFT, LFT, BMP, or blood typing. But it is a huge list:

A Complete Blood Count (CBC)
Blood Glucose Test to check blood sugar levels.
Liver Function Test
Kidney Function Test
Thyroid Function Test
Test for Heart Disease Risk.
Karyotyping (chromosome testing) for a genetic disorder.
Coagulation Test to access blood clotting time.
Electrolyte Test to check levels of minerals.
Erythrocyte Sedimentation Rate (ESR) for arthritis and inflammatory conditions.
Blood Cholesterol Test
Blood Enzyme Test
Blood Typing
Full blood count (FBC)

Blood Typing and Groups

Four common blood types are A, B, AB, and O; they can be +ve or -ve depending on the blood’s Rh factor. There are eight blood groups, as shared below:

A+
A –
B+
B –
AB+
AB –
O+
O –

As per the American Red Cross, the most common blood type is type O, followed by A, B, and AB. They are different in all geographical areas; the most common blood type is AB for Asians, B for African Americans, and O for Caucasians. In the USA, it is O, and in Europe, it is A.

Risk factors associated with the Blood Test

There might be a little pain, bleeding, soreness or bruise at the spot where the needle is inserted to withdraw the blood, but it goes off quickly.

Preparing for the Blood Test

No significant preparation is required for the blood test, as most blood tests are done safely in normal conditions. You may be advised to:

Fasting for a few hours, up to 10-11 hours, means not eating or drinking anything apart from water.
Stopping a few medicines for some time as medicines can interfere with the test result accuracy.

What to expect from the Blood Test

A trained phlebotomist performs procedures for blood collection:

Venipuncture is the most common way of blood collection from a vein in the arm. A tight band (tourniquet) is tied around your upper arm, which causes the vein to swell, thus making the blood collection easier. The area from where the blood is to be collected is cleaned with an antiseptic swipe.
A small needle is inserted into the vein, and the required amount of blood is collected into a vial attached to the needle. The band around the upper arm is removed, and the skin is covered with cotton and plaster to keep it clean.
Blood samples from children can also be taken from the back of the hand. To make the process less painful, a special spray or cream is applied to the skin to numb it.
A finger prick test is for a minimal amount of blood and is used for rapid or at-home tests.
A heel stick test is a procedure for collecting blood samples of a newborn baby. The baby’s heel is cleaned with alcohol or antiseptic swipe, a tiny needle is pricked, and a few drops of blood are collected. The skin is covered with a bandage after the collection.
An arterial blood test is done to measure oxygen levels. Blood is taken from the arteries, as arterial blood has higher levels of oxygen than venous.

Possible results of the Blood Test

Results are sent to the doctor and also to you. It may take a few days or a week, depending on the test. Consult the doctor as soon as you receive the result.

When to see a doctor?

Any blood test will give the report, range, observation, and results, but to know the details about your condition or to know if any other further examination is required or not. You must consult the doctor for a complete diagnosis and treatment plan.