What is leukemia?

Leukemia is when your blood gets too crowded because the factory makes too many workers who aren't ready to work yet.

Imagine your body is a busy city and blood are the roads carrying supplies. Inside those roads, there are tiny red blood cells (the delivery trucks) that bring oxygen to every corner of your house. There are also white blood cells (the security guards) that fight off invaders like germs.

In leukemia, the bone marrow is the factory where these workers are made. Usually, the factory builds new red and white cells only when they are needed. But in leukemia, something goes wrong with the "training school." The white blood cells grow up too fast and get stuck as babies or teenagers, called leukemic blasts.

These immature blasts don't know how to fight germs properly. Instead of leaving the factory to go patrol the streets (your bloodstream), they pile up inside. It is like a classroom full of five-year-olds trying to squeeze into tiny cars. They take up all the space.

Because there are so many blast cells jamming up the roads, the healthy red blood cells and normal white blood cells have no room to grow or move around. This is called crowding out. The delivery trucks can't bring enough oxygen, which makes you feel tired. The security guards can't stop infections because they are either too young to be strong or just too many of them getting in each other's way.

Sometimes the blueprint for making these cells has a typo. This is a mutation in the DNA. It isn’t magic; it’s more like a glitch in the instruction manual. The factory keeps printing copies of the same confused worker, over and over again. These abnormal cells multiply quickly, turning your blood into a congested highway of young workers who are standing around doing nothing instead of doing their jobs.