Blood tests are a routine and important part of monitoring your child during cancer treatment. But figuring out what all the different terms and numbers mean can be a bit confusing.
Here’s what you should know about understanding blood test results when your child is being treated for cancer.
Blood Test Basics
Understanding The Different Types Of Blood Tests
There are two main kinds of blood tests that pediatric cancer patients undergo: Complete blood counts (CBCs) and blood chemistry studies, says CureSearch for Children’s Cancer.
Complete Blood Count
CBCs are the most common kind of blood test for kids with cancer because they look at how treatment impacts their bone marrow, explains CureSearch. Blood cells are made in the bone marrow, so a CBC can let your child’s medical team know if she:
- Is ready for the next round of chemo
- Needs a transfusion
- Has a higher risk of getting an infection
Blood Chemistry Study
Blood chemistry studies look at different electrolytes and elements—such as sodium and potassium—in your child’s blood, says CureSearch.
These tests can give the medical team an idea of how his organs are working, which is important because some treatments can damage organs like the liver or kidneys.
Figuring Out How Often Your Child Needs Blood Tests
Your child’s medical team will determine how often she’ll need to have her blood tested. Some kids get blood tests done more frequently than others, depending on where they are in treatment.
So, kids who are in a more intensive phase may get their blood tested once or twice a week. But kids in a less intensive phase may only be tested monthly.
Understanding Blood Test Results
Blood tests can help monitor a child’s cancer in a few different ways.
Blood And Urine Markers For Different Cancers
One way blood tests help pediatric cancer patients is by letting the medical team look at substances—called markers—associated with certain kinds of cancers.
Alpha Fetoprotein (AFP)
AFP is made in a developing baby’s liver before birth, says the National Library of Medicine. While it doesn’t necessarily have any real purpose after birth, measuring its levels in your child’s blood can still be useful.
That’s because kids with hepatoblastoma—a form of liver cancer—or germ cell tumors may have abnormal levels of AFP.
Homovanillic Acid (HVA) and Vanillylmandelic Acid (VMA)
HVA and VMA are the products of a type of neurotransmitter called a catecholamine, explains the American Society of Clinical Oncology. They are normally passed through a person’s body in urine.
Neuroblastoma patients usually have high levels of HVA and/or VMA.
Beta-Human Chorionic Gonadotropin (BHCG)
BHCG is a hormone usually associated with pregnancy, but patients with some kinds of cancer, including germ cell tumors, can have high levels of it as well, says the National Cancer Institute.
Key Numbers To Look Out For During Treatment
Blood tests also measure the levels of different types of cells and substances found in the blood to see how a child’s body responds to treatment.
Absolute Neutrophil Count (ANC)
Neutrophils are a type of white blood cell that help your child’s body fight off infections. Children with low levels of ANC are considered neutropenic, meaning they are at a higher risk of infection. If they have a fever as well, they may need to be hospitalized for antibiotics.
Hemoglobin is a protein in red blood cells. It carries oxygen to tissues in the body, explains CureSearch.
Your child’s hemoglobin level should be mid-range. High hemoglobin levels can be a sign of dehydration or kidney problems. Low levels may be a sign of anemia, says CureSearch.
At Children’s, when we measure hemoglobin, we want hemoglobin to be above 7g/dL most of the time. But because kids with anemia may need a blood transfusion before their hemoglobin is as low as 7, we also take their other symptoms into account.
So, if they are suffering from fatigue, shortness of breath, tachycardia, and other issues, we may transfuse them even if their hemoglobin number is higher.
It’s important to monitor a child’s platelets—the small blood cells that help blood clot—because low platelet counts put him at risk for bleeding, explains CureSearch.
Kids with low platelet counts sometimes also need transfusions. But just like hemoglobin, if a child is symptomatic, we may have to transfuse them even if their counts are higher.
Why Standard Ranges Do—And Don’t—Matter
In general, the labs that perform blood tests determine which numbers or ranges are considered standard. But those standards are for a person who does not have cancer.
So, the majority of kids undergoing chemo or other cancer treatments will have values that are expected for someone on chemo but do not fall in that normal lab-defined range.
This means that simply using the standards the lab provides isn’t always useful in the context of undergoing cancer treatment. This is why it’s important to talk to your child’s medical team about her blood test results.