|
Understand Childhood Cancers and Blood Disorders
Complete Blood Count (CBC)
A complete blood count (CBC) is one of the easiest blood tests to obtain and an important diagnostic tool utilized to determine the health status of a child. It can be obtained by a fingerstick where a few drops of blood are taken from a finger or heel, venipuncture where blood is obtained by inserting small needles into a vein, or from a central line in patients with cancer.
There are three important components of the CBC that are helpful in assessing many different conditions. They are the red blood cell (RBC), white blood cell (WBC) and the platelets (PLT). Each blood cell originates in the bone marrow.
The Red Blood Cell (RBC)
The RBC's are primarily responsible for transporting oxygen from the lungs to the vital organs and tissues and carbon dioxide from the organs and tissues back to the lungs. They have a life span of about 120 days. Hemoglobin (HGB) is the component of the RBC that binds and carries the oxygen to the tissues. The normal value varies based on age and gender. The range can be nine to 17.5. The Hematocrit (HCT), the percentage of RBC's in whole blood, is approximately 30-45. The HGB and HCT exist in a fixed ratio where the HGB is usually one third of the HCT.
Anemia is when the red blood cell count is low. When anemic, your body needs to send oxygen to your important organs (ie: kidneys, lungs, heart, brain) at the expense of other organs. The body accommodates the low red blood cell count by slowing you down, causing fatigue, making your heart beat faster, causing headaches and making you look pale.
Platelets (PLT)
Platelets are the cellular fragments needed to form a clot and prevent bleeding. PLT's clump together at the site of a broken vessel, stimulate the clotting process, and provide for plug formation at the site of the injury. A PLT's lifespan is eight to10 days. The normal range is 150,000-450,000/mm .
A decreased PLT count (thrombocytopenia) can be caused by:
- decreased production (leukemias, bone marrow failure syndromes),
- increased PLT destruction (viruses, medications, antibodies) and,
- abnormal pooling (in the spleen).
Patients whose PLT count is low bruise easily and have petechiae (little red dots on the skin). They may also bleed from the gums while brushing teeth or even have nose bleeds.
White Blood Cells (WBC)
The WBC's (leukocytes) are responsible for fighting infection. There are many different types, each with a different function. The WBC's lifespan varies with each different type, from hours to days. The normal range is 4,500-12,000/mm but that also varies with age and gender.
The WBC Differential (diff) breaks down the WBC count into the various types of WBC's, each expressed as a percentage of the total WBC count. Neutrophils are the first to respond to an invading organism or bacteria by engulfing and destroying it. They are the most important of the WBC's and have the shortest lifespan of only a few hours. The normal range is 30-60 percent. A rise in the neutrophil count is usually a response to a bacterial infection, tissue damage or an inflammatory condition. The Absolute Neutrophil Count (ANC) is calculated to assess potential for infection. Neutropenia is defined as an ANC of less than 1,000 cells/mm . Neutropenia leaves a patient at risk for potentially serious infections. Monocytes are the second line of defense against foreign invaders. They are capable of engulfing and destroying the foreign substances as well; however, they respond late during the acute phase of an infectious process. Their normal range is five to 10 percent, with approximately an eight hour lifespan. Lymphocytes are responsible for the regulation of the immune system, and are most commonly seen in response to viral and bacterial infections and some allergic conditions. The normal range is 15-45 percent, with a life span of 100-300+ days. Eosinophils are commonly produced in response to allergic disorders and parasitic infections. Their normal range is zero to five percent. Basophils respond to chronic inflammatory states and hypersensitivity reactions. The normal range is zero to one percent.
Calculating the ANC:
ANC = (Neutrophils * total WBC) / 100
Germ Cell Tumors in Children
Germ cells are reproductive cells that are destined to become the tissues of the definitive gonads in the developing embryo. In males, these cells give rise to testicular tissues and in females they give rise to ovarian tissues. These cells migrate in fetal life from the cephalic area (head) along the midline to the pelvis where they give rise to reproductive tissues. Germ Cell tumors are a group of benign (not cancerous) or malignant (cancerous) tumors that may arise anywhere along the migration path. Examples of germ cell tumors are teratomas (often benign), germinomas and yolk sac tumors. Malignant germ cell tumors are among the less common tumors of childhood and account for about 15 percent of malignant tumors in adolescents and less than five percent of tumors in patients under 15 years of age. Malignant germ cell tumors, like other malignant solid tumors, have the ability to spread throughout the body. When the spread occurs via the bloodstream to a distant site unrelated to the location of the original tumor, the tumor is said to have metastasized. When this occurs with germ cell tumors, they commonly spread to the liver, lungs and lymph nodes but may spread to other areas of the body such as bone or the bone marrow.
Some abnormalities of the central nervous system and some malformations of the lower spine and reproductive tract may predispose to these types of tumors. Cryptorchidism, a failure of the testicle to completely descend into the scrotum, also is known to predispose to these types of tumors. The common presenting clinical manifestations of these tumors depend on the patient's age and the tumor location. In males, this is usually a painless testicular mass but it can sometimes be painful. In girls, these tumors often present with abdominal fullness or discomfort and can initially be thought to be appendicitis. Occasionally, there will be changes in bowel or bladder function or muscle weakness. In newborn infants, germ cell tumors can present with a large swelling in the area of the coccyx and these are usually diagnosed by sonogram before birth. These tumors usually secrete biological markers such as serum alpha fetoprotein which can be measured in the blood and used to tract the activity of the tumor and assess the effectiveness of treatment. Imaging studies, including ordinary x-rays, CT scans, sonograms and MRI scans, can be quite helpful in diagnosing and locating the tumor.
The location of the primary germ cell tumor and the patient's age are also important determinants in selecting treatment and predicting outcome. Studies done at the time of diagnosis can detect spread of the tumors so that the amount of tumor present can be staged or assessed. Treatment for these tumors depends on location and how much of the tumor may have been removed surgically. Many patients with germ cell tumors require additional treatment with chemotherapy after initial surgery to destroy cells that remain in the body. This residual tumor tissue is sometimes microscopic in size and cannot be seen by standard imaging studies or by surgeons and must be controlled by drugs which are usually given by injection.
When medications are given by injection, the treatment is said to be systemic. This means that the drugs are carried throughout the body by the blood stream. Many pediatric patients with germ cell tumors may only require a few months of chemotherapy, during which time children can keep up with their school assignments and can actually attend school on an intermittent basis. For the first year following completion of treatment, patients are seen in follow up once a month by a pediatric oncologist and undergo follow-up blood tests and imaging studies.
Hemophilia
Hemophilia is an inherited disease that prevents the blood from clotting properly. Children with hemophilia have a deficiency of a protein, also called a "clotting factor," that is necessary to clot the blood and stop bleeding. There are two major forms of hemophilia: hemophilia A (80 percent of cases) and hemophilia B (20 percent of cases). Both types of hemophilia are carried on the X chromosome and occur in boys who inherit that mutated X chromosome from the mother. In rare situations even females can have symptomatic hemophilia. Hemophilia occurs across all populations, and all races equally.
A woman who gives birth to a child with hemophilia is known as a "carrier" and often has male relatives with a history of hemophilia. In about 30percent of cases, there is no family history of hemophilia. This means either that the gene has "skipped generations" (that is, passed down through several female carriers without any baby male being affected) or the change in the X chromosome is new (a "spontaneous mutation" or "de novo"). Hemophilia A is found almost exclusively in males, occurring in about one in every 5,000 live male births. An estimated 17,000 individuals in the U.S. have hemophilia A. By contrast, hemophilia B is much less common occurring in about one in 25,000 male births and affects about 3,300 individuals in the U.S.
When a woman carries the hemophilia mutation, each pregnancy can have one of four outcomes:
- A girl who is not a carrier
- A girl who is a carrier
- A boy without hemophilia
- A boy with hemophilia
In other words, each pregnancy of a woman who is a known carrier has a 25 percent chance of having a child with hemophilia. If the fetus is known to be a male, then his chance of having hemophilia is 50 percent. About 30 percent of male infants will have bleeding with circumcision and that procedure should be delayed, whenever possible. All daughters of a man with hemophilia will be carriers but none of his sons will have hemophilia. Genetic counseling is available in order to help you make family planning decisions.
People with hemophilia A, also called "classic hemophilia," have a deficiency in clotting factor VIII. Hemophilia is classified as "severe," "moderate," or "mild," depending on the level of factor VIII. This classification gives a rough guide for the patient's expected rate of bleeding episodes. The symptoms of hemophilia A and B are similar and will be discussed together.
Mild hemophilia (six percent to 49 percent factor VIII or IX level) may bleed only after serious injury, trauma, or surgery. Often, this form of hemophilia is discovered incidentally in adulthood. Commonly, mild hemophilia is not detected until an injury or surgery (e.g. tonsillectomy, tooth extraction, etc) results in disproportionate bleeding. The first bleeding episode may not occur until adulthood. These patients lead a normal life and may participate in athletic activities except contact sports.
Moderate hemophilia (one to five percent factor VIII or IX level) occurs in about 15 percent of the hemophilia population. Patients sustain bleeding episodes after injuries. They may, at times, report occasional bleeding episodes without a clearcut cause. We call those "spontaneous bleeding episodes." These patients may also participate in all athletic activities without serious limitations except for contact sports.
Severe hemophilia (less than one percent factor VIII or IX level) make up roughly 60 percent of all hemophilia patients. Bleeding can occur following an injury and patients may have frequent spontaneous bleeding episodes, often into the joints ("hemarthroses") and muscles. Joints that are frequently affected by bleeding are called "target joints". Target joints often progress to arthritic joints because of the gradual destruction of the cartilage layer. Other types of bleeding include mouth, nose, bloody urine, gastrointestinal and even bleeds into the head.
Generally, simple cuts are treated the same way one would treat such injuries in any child - cleaning the cut, applying pressure, and placing a band-aid. Patients with mild hemophilia can control the bleeding using desmopressin acetate (DDAVP that comes as a nasal spray) when the bleeds are minor. Serious bleeds, such as joint or muscle bleeds demand treatment with infusion of factor concentrate (either factor VIII or IX, depending on the hemophilia). Such infusions help the patient clot rapidly and properly.
In the past most factor VIII and IX products were made from donated human blood and plasma. Nowadays "recombinant factors" which are made in a laboratory and do not use human blood are used almost exclusively. The recombinant factor therapy is considered safer. All factor treatments are given intravenously.
In some cases of severe hemophilia, doctors sometimes recommend giving regular factor replacement infusions (a strategy known as "prophylaxis") in order to prevent most bleeding episodes. Major hemophilia authorities recommend prophylaxis as optimal treatment for children with severe hemophilia A and B.
|
