That's very unusual that his kidneys are effected if he has leukemia
As you probably know leukemia is a cancer of the blood cells. Generally, leukemia refers to cancers of the White blood cells (WBC)
WBCs are a vital part of your immune system. They protect your body from invasion by bacteria, viruses, and fungi, as well as from abnormal cells and other foreign substances. In leukemia, the WBCs don’t function like normal WBCs. They can also divide too quickly and eventually crowd out normal cells.
It cdm effect the liver and other vital organs but rarely the kidneys