Blood tests and diagnosing illness: what can blood tell us about what’s happening in our body?

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The Conversation – 27th July 2017

By Karen Dwyer

Doctors have continually sought better ways of determining what is wrong with a patient. When you visit a GP’s office or emergency department with an unknown illness, a doctor will commonly draw some blood to gain a better idea of what’s going on inside your body. Blood is perhaps the most important window through which we can peer into a person’s health or illness.

About 7% of our body weight is our blood, and our heart spits out about five litres of blood every minute. Oxygenated blood leaves the left side of the heart via the aorta and the arteries – which permeate every tissue in the body – and returns to the right side of the heart via the veins. From the right side of the heart, blood is pumped into the lungs where it is oxygenated, returning to the left side of the heart.

In about two tablespoons of blood there’s a lot we can tell about our health.

What blood can tell us

When someone presents at an emergency department, the initial panel of tests will include a full blood count. This details the red blood cell count, white blood cell count and platelets; electrolytes (the substance in our blood that carries an electric charge that is vital for life) to measure kidney function; liver function tests and “C-reactive protein” which can tell us if there is inflammation somewhere in the body. READ MORE AT:


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