Microscopic polyangiitis is a type of vasculitis. Almost all people with microscopic polyangiitis have kidney problems that can lead to raised blood pressure and kidney failure.
People may find that they're tired because of anaemia. Anaemia is a shortage of haemoglobin (oxygen-carrying pigment) in the blood which makes it more difficult for the blood to carry oxygen around the body.
Blood tests can show whether the kidney is inflamed. Microscopic polyangiitis can also involve the lungs, with bleeding that can cause breathlessness.
Find out more about vasculitis.