Blood

Anaemia is when you do not have enough healthy red blood cells to carry the oxygen you need around your body. If you have anaemia, you may feel tired, light-headed and weak.

A deep vein thrombosis (DVT) is a blood clot in a vein that runs through the muscle of your calf or thigh. The clot can sometimes break off and travel to your lungs, causing a very serious condition called pulmonary embolism (PE). DVT is treated with blood thinning medication (anticoagulants) to stop more clots forming.

You can get iron overload if too much iron builds up in you body.

Iron is a mineral your body needs to make red blood cells, which carry oxygen to your body.

Being low in vitamin B12 can cause serious problems. Vitamin B12 is needed to make red blood cells that carry oxygen around your body. It also helps your nerves and brain.