Blood cells are made inside your bone marrow, and that’s where leukemia starts. It causes your body to make white blood cells that grow out of control and live longer than they’re supposed to. And unlike normal white blood cells, they don’t help your body fight infection.
There are many different forms of leukemia. Some get worse quickly (acute). You’ll probably feel very sick very suddenly, like you’ve come down with the flu. Other forms can take years to cause symptoms (chronic). Your first clue may be abnormal results on a routine blood test.
Most signs of leukemia happen because the cancer cells keep your healthy blood cells from growing and working normally.