Rosa Peguero was asleep in her hospital bed when she felt someone gently rubbing her shoulder.
She opened her eyes and found Dr. Peña standing beside her bed, smiling. Dr. Peña is Rosa’s hematologist, and she helps lots of kids who have problems in their blood. Rosa sees Dr. Peña every few months because Rosa has a blood condition called Sickle Cell Disease. Rosa was in the hospital because she had been feeling a lot of pain in her back, arms and legs over the past few days.
“How are you feeling today, sweetie?” asked Dr. Peña.
Rosa shrugged. Her back and her arms were still hurting, but she was feeling lot better than before she took the medicine that Dr. Peña gave her. “A little better,” she replied.
“Good,” said Dr. Peña, smiling. “That’s what I like to hear.”
“Dr. Peña?” said Rosa. “Where is the pain coming from? I felt good at school two days ago, and then all of a sudden, my back, my legs and my arms all started to hurt. What’s different about my blood compared to other kids’?”
“That’s a good question, Rosa,” said Dr. Peña. “It’s because the red blood cells in your blood are different. Let me tell you a story about one of your red blood cells named Eri.”
Eri is an erythrocyte, which is a medical word for red blood cell. Eri and trillions of other red blood cells live in the blood.
Red blood cells have the important job of delivering oxygen to all the different parts of the body - the heart, the brain, the skin, the muscles and even the toes.
Every part of the body needs oxygen to be active and healthy, in the same way that people need to eat food to be active and healthy. Red blood cells like Eri work with other types of cells in your blood, like white blood cells and platelets.
Every day, Eri travels many times to the lungs to pick up oxygen. Oxygen enters your lungs every time you take in a breath of air. Eri loads four oxygen molecules onto a special backpack called hemoglobin.
Sometimes, when traveling through the blood vessels, Eri passes through the spleen. The spleen is an organ inside the belly. The spleen makes sure that all the red blood cells in the body are healthy ones. When it finds blood cells that are injured or too old to do their job, it snatches them up and takes them out of the blood.
One day, Eri was doing his usual job of delivering oxygen throughout the body. He had picked up four oxygen molecules from the lungs and was dropping them off at different places in the body. He had one oxygen molecule left in his hemoglobin backpack and he was starting to feel funny. He looked down and saw that his usual round shape had changed into a C-shape!
“What’s happening?” he thought.
Eri tried to keep swimming within the blood vessel inside the spleen to look for help, but discovered that he was stuck to the vessel wall! He touched his skin and noticed it was stickier than normal. “WHACK!” Eri suddenly felt something crash into him from behind. It was his friend Rubi, another red blood cell. She, too, had a funny new C-shape, and was now stuck to Eri.
“Why are we so sticky?” Eri asked Rubi. “And why are we bent like this?”
There was a rush of new blood flowing through the blood vessel. Eri saw hundreds and hundreds of nice and round, healthy-looking red blood cells entering the blood vessel. They had oxygen loaded up onto hemoglobin packs that looked different from Eri’s and Rubi’s, and they were delivering the oxygen throughout Rosa’s body.
Eri was relieved to see that all around him were round, healthy red blood cells dropping off oxygen to all the parts of the body that needed it. He also spotted fresh, young red blood cells floating around. “The bone marrow must have realized that we haven’t been able to deliver oxygen, so it’s producing lots and lots of new red blood cells to help get our job done!”
“What happens now, Rubi?” asked Eri.
“We’ve done a great job delivering oxygen up until now, but with this shape, we can’t do it anymore,” she replied. “Now it’s time for us to head to the spleen, where we’ll be recycled, so the bone marrow can make brand new blood cells!”
Eri and Rubi floated toward the spleen, comforted by the thought that the new red blood cells would help Rosa feel better.
“So Eri and Rubi get recycled by the spleen, the blood cells from the transfusion are working in the body and the bones make lots of new, round red blood cells to carry oxygen around. After a few days, the vaso-occlusive crisis is over, and things start feeling normal again,” said Dr. Peña.
“So there could be clumps of red blood cells like Eri and Rubi in my back and in my arms and legs?” asked Rosa. “And that’s why it hurts so much?”
“That’s absolutely right,” said Dr. Peña. “I know it can be a really scary experience to have a vaso-occlusive crisis and be feeling all that pain. But we have medicines to help you feel better, and so you can always tell me if you’re in pain. I promise you’ll be feeling well soon.”
“Thanks, Dr. Peña!” said Rosa. “I’m feeling stronger already.” Rosa reached over and gave Dr. Peña a big hug. She looked down at her legs and imagined all the new, round, red blood cells floating through and delivering oxygen throughout her body.