Read the following context and answer the question.
Context: A blood test freaked me out . So when they took what felt like 2 gallons of my blood , I was getting a little bit nervous . So I pushed the doctor until he finally told me what he thought the problem was . He told me that because of the rapid weight loss and growth , that it was most likely an aggressive form of Leukemia .
Question: Why did the narrator undergo a blood draw ?
Answer:


They had rapidly lost weight .