Blood Counts and Record Keeping

The following excerpt is taken from Appendix B of Childhood Leukemia: A Guide for Families, Friends, and Caregivers, 2nd Edition by Nancy Keene, copyright 1999 by O'Reilly & Associates, Inc. For book orders/information, call (800) 998-9938. Permission is granted to print and distribute this excerpt for noncommercial use as long as the above source is included. The information in this article is meant to educate and should not be used as an alternative for professional medical care.

Keeping track of their child's blood counts becomes a way of life for parents of children with leukemia. Unfortunately, misunderstandings about the implications of certain changes in blood values can cause unnecessary worry and fear. To help prevent these concerns, and to better enable parents to help spot trends in the blood values of their child, this article explains the blood counts of healthy children, the blood counts of children being treated for leukemia, and what each blood value means.

Values for healthy children

Each laboratory and lab handbook has slightly different reference values for each blood cell, so your lab sheets may differ slightly from those that appear later in this article. There is also variation in values for children of different ages. For instance, in children from newborn to four years old, granulocytes are lower and lymphocytes higher than the numbers listed below. Geographic location affects reference ranges as well. The following table lists blood count values for healthy children:

Values for children on chemotherapy

Blood counts of children being treated for leukemia fluctuate wildly. White blood cell counts can go down to zero or be above normal. Red cell counts go down periodically during treatment, necessitating transfusions of packed red cells. Platelet levels also decrease, requiring platelet transfusions. Absolute neutrophil counts (ANC) are closely watched as they give the physician an idea of the child's ability to fight infection. ANCs vary from zero to in the thousands.

Oncologists consider all of the blood values to get the total picture of the child's reaction to illness, chemotherapy, radiation, or infection. Trends are more important than any single value. For instance, if the values were 5.0, 4.7, 4.9, then the second result was insignificant. If, on the other hand, the values were 5.0, 4.7, 4.6, then there is a decrease in the cell line.

The explanations below will describe each blood value. If you have any questions about your child's blood counts, ask your child's doctor for a clear explanation. Especially in the beginning, many parents agonize over whether the rapid changes in blood counts (often requiring transfusions, changes in chemo dosages, or whether the child can have visitors) are normal or expected. The only way to address your worries and prevent them from escalating is to ask what the changes mean.

What do these blood values mean?

The following sections explain each line of the above list of blood values. See the sample lab data sheets below to get an idea of the different ways these values might be displayed on the actual lab reports prepared for your child.

Click here for "Sample lab data sheets."

Hemoglobin (Hgb)

Red cells contain hemoglobin, the molecules that carry oxygen and carbon dioxide in the blood. Measuring hemoglobin gives an exact picture of the ability of the blood to carry oxygen. Children may have low hemoglobin levels at diagnosis and during the intensive parts of treatment. This is because both cancer and chemotherapy decrease the bone marrow's ability to produce new red cells. During maintenance, your child's hemoglobin level will be higher than during induction and consolidation, but still lower than that of a healthy child. Signs and symptoms of anemia-pallor, shortness of breath, fatigue-may start to show if the hemoglobin gets very low.

Hematocrit (HCT)
also called PCV (packed cell volume)

The purpose of this test is to determine the ratio of plasma (clear liquid part of blood) to red cells in the blood. Blood is drawn from a vein, finger prick, or from a Hickman or Port-a-cath and is spun in a centrifuge to separate the red cells from the plasma. The hematocrit is the percentage of cells in the blood; for instance, if the child has a hematocrit of 30 percent, it means that 30 percent of the amount of blood drawn was cells and the rest was plasma. When the child is on chemotherapy, the bone marrow does not make many red cells, and the hematocrit will go down. The child may be given a transfusion of packed red cells when the hematocrit goes below 18 to 19 percent. Even during maintenance the bone marrow is partially suppressed, so the hematocrit is often in the low to mid-thirties. This results in less oxygen being carried in the blood, and your child may have less energy.

Red blood cell count (RBC)

Red blood cells are produced by the bone marrow continuously in healthy children and adults. These cells contain hemoglobin, which carries oxygen and carbon dioxide throughout the body. To determine the RBC, an automated electronic device is used to count the number of red cells in a liter of blood.

Red cell indices (MCV, MCH, MCHC) are mathematical relationships of hematocrit to red cell count, hemoglobin to red cell count, and hemoglobin to hematocrit. This gives a mathematical expression of the degree of change in shape found in red cells. The higher the number (low teens are fine), the more distorted the red cell population is.

White blood cell count (WBC)

The total white blood cell count determines the body's ability to fight infection. Treatment for cancer kills healthy white cells as well as diseased ones. Parents need to expect prolonged periods of low white counts during treatment. To determine the WBC, an automated electronic device counts the number of white cells in a liter of blood. If your lab sheet uses K/ul instead of mm³, multiply by 1000 to get the value in mm³. For example, on the sample lab sheet, the total WBC is 0.7 K/ul. Therefore, 0.7 x 1000 = 700 mm³.

White blood cell differential

When a child has blood drawn for a complete blood count (CBC), one section of the lab report will state the total white blood cell count and a "differential." This means that each type of white blood cell will be listed as a percentage of the total. For example, if the total WBC count is 1500 mm³, the differential might appear as in the following table:

You might also see cells called metamyelocytes, myelocytes, promyelocytes, and myeloblasts listed. These are immature white cells usually only found in the bone marrow. They may be seen in the blood during recovery from low counts.

The differential is obtained by microscopic analysis of a blood sample on a slide.

Absolute neutrophil count (ANC)

The absolute neutrophil count (also called the absolute granulocyte count or AGC) is a measure of the body's ability to withstand infection. Generally, an ANC above 1,000 means that the child's infection-fighting ability is near normal.

To calculate the ANC, add the percentages of neutrophils (both segmented and band) and multiply by the total WBC. Using the example above, the ANC is 49 percent + 1 percent = 50 percent. 50 percent of 1,500 (.50 x 1,500) = 750. The ANC is 750.

Platelet count

Platelets are necessary to repair the body and to stop bleeding through the formation of clots. Because platelets are produced by the bone marrow, platelet counts decrease when a child is on chemotherapy. Signs of lowering platelet counts are small vessel bleeding such as bruises, gum bleeding, or nosebleeding. Platelet transfusions may be given when the count is very low (between 10,000-20,000 mm³) or when there is bleeding. Platelets are counted by passing a blood sample through an electronic device.

Approximately one-third of all platelets spend a great deal of time in the spleen. Any splenic dysfunction such as enlargement may cause the counts to drop precipitously. If the spleen is removed, platelet counts may skyrocket. This transient thrombocytosis (elevated platelet count) will abate within a month.

Alanine aminotransferase (ALT)

ALT is also called SGPT (serum glutamic pyruvic transaminase). When doctors talk about "liver functions," they are usually referring to tests on blood samples that measure liver damage. If the chemotherapy is proving to be toxic to your child's liver, the damaged liver cells release an enzyme called ALT into the blood serum. ALT levels can go up in the hundreds or even thousands in some children on chemotherapy. Each institution and protocol has different points at which they decrease dosages or stop chemotherapy to allow the child's liver to recover. If you notice a change in your child's ALT, ask for an explanation and plan of action (for example, "John's ALT is now 450, what is your plan to reduce or stop the chemotherapy to allow his liver to recover?")

I was very interested in my daughter's blood counts throughout her treatment. I also tried to get information without making people mad. If I asked a question and received an unsatisfactory answer, I would reply in a nice way, "I am worrying about this and would really appreciate a few minutes of your time to explain it to me." I found the attendings and clinic director to be the most willing to provide explanations. If you get a ridiculous reply (once a fellow patted me on the head and said, "It's our job to think about these things, not yours"), go find someone else to ask.

Aspartate aminotransferase (AST)
also called serum glutamic oxaloacetic transaminase (SGOT)

SGOT is an enzyme present in high concentrations in tissues with high metabolic activity, including the liver. Severely damaged or killed cells release SGOT into the blood. The amount of SGOT in the blood is directly related to the amount of tissue damage. Therefore, if your child's liver is being damaged by the chemotherapy, the SGOT can rise into the thousands. In addition, there are other causes for an elevated SGOT, such as viral infections, reaction to an anesthetic, and many others. If your child's level jumps unexpectedly, ask the physician for an explanation and a plan of action.

Bilirubin

The body converts hemoglobin released from damaged red cells into bilirubin. The liver removes the bilirubin from the blood, and excretes it into the bile, which is released into the small intestine to aid digestion.

Normally there is only a small amount of bilirubin in the bloodstream. Bilirubin rises if there is excessive red blood cell destruction or if the liver is unable to excrete the normal amount of bilirubin produced.

There are two types of bilirubin: indirect (also called unconjugated), and direct (also called conjugated). An increase in indirect (unconjugated) is seen when destruction of red cells has occurred, while an increase of direct (conjugated) is seen when there is a dysfunction or blockage of the liver.

If excessive amounts of bilirubin are present in the body, the bilirubin seeps into the tissues, producing a yellow color called jaundice.

If your child's total bilirubin rises above normal levels, ask the physician for an explanation and plan of action.

Your child's pattern

Each child develops a unique pattern of blood counts during treatment, and observant parents can help track these changes. This article contains a record-keeping sheet that you can use to record your child's blood values. If there is a change in the pattern, show it to your child's doctor and ask for an explanation. Doctors consider all of the laboratory results to decide how to proceed, but they should be willing to explain their plan of action to you so that you better understand what is happening and worry less.

Click here for an example of a record-keeping sheet.

If your child is participating in a clinical trial and you have obtained the entire clinical trial protocol, it will contain a section that clearly outlines the actions that should be taken by the oncologist if certain changes in blood counts occur. For example, my daughter's protocol has an extensive section which lists each drug and when the dosage should be modified. For vincristine it states:

Vincristine

1.5 mg/m² (2 mg maximum) IV push weekly x 4 doses days 0, 7, 14, 21.

Seizures

Hold one dose, then reinstitute.

Severe foot drop, paresis, or ilius

Hold dose(s): when symptoms abate, resume at 1.0 mg/m²; escalate to full dose as tolerated.

Jaw pain

Treat with analgesics; do not modify vincristine dose.

Withhold if total bilirubin > 1.9 mg/dl. Administer 1/2 dose if total bilirubin 1.5-1.9 mg/dl.

Resources

If you would like more information on laboratory diagnostic tests, two good books that can often be found in the reference section of your local library are:

Everything You Need to Know About Medical Tests, written by 70 doctors and medical experts. Springhouse, PA: Springhouse Corporation, 1996.

Sobel, David, MD, and Tom Ferguson, MD. The People's Book of Medical Tests. New York: Summit Books, 1985.