n HOW IS APLASTIC ANEMIA DIAGNOSED? When a child develops signs of aplastic anemia, one of the first steps to making the diagnosis is a blood test. Blood tests are done by inserting a needle into the child’s arm or hand to draw blood that can be sent to a laboratory for analysis. Drawing blood can be difficult for the child and parent, but it is necessary to obtain an accurate diagnosis. A test called the complete blood count (CBC) measures the number of WBCs, RBCs, and platelets that are circulating in the blood. In a child with aplastic anemia, all of these numbers are low. A reticulocyte count, which assesses the number of healthy young RBCs the body is making, may be low as well.
Your healthcare team also will order a chem- istry panel to check your child’s electrolyte balance and to evaluate how well the kidneys and liver are working. The blood sample also may be be tested for recent viral infections. These tests will help your healthcare team look for other causes of decreased blood counts and help confirm the diagnosis of aplastic anemia. The diagnosis of aplastic anemia is confirmed by a bone marrow aspirate and biopsy. These tests help your healthcare team to understand the reason for your child’s marrow failure
and to rule out other reasons for low blood counts. During a bone marrow aspirate, a needle is inserted through the bone, generally into the iliac crest (hip bone), and a sample of the bone marrow from the spongy space in the bone is removed. The bone marrow is then examined under a microscope by a specially trained doctor (pathologist or hematologist) to see if WBCs, RBCs, and platelets are being pro- duced normally. The pathologist also looks for any abnormal cells, such as immature blood forming cells (blasts), which can indicate leukemia, and dysmorphic (abnormal-looking) cells, which can indicate a dif- ferent disease. The bone marrow also is assessed for protein expression of malignant (cancer) cells, which can indicate leukemia, and chromosomal abnormalities, which can diagnose other diseases. In children with aplastic anemia, protein expression and chromosome tests are normal. A bone marrow biopsy is necessary to diagnose aplastic anemia. During the bone marrow biopsy, a nee- dle is inserted into the hip bone and a small “core,” or a cylinder-shaped piece of the bone, is obtained. The pathologist looks at this core and determines how cellular the marrow is. In children with aplastic anemia, the bone marrow is hypocellular, which means very few of the blood-forming cells are seen under the microscope. The degree of cellularity is graded as a percentage. That percentage helps determine the severity of the aplastic anemia. The bone marrow aspirate and biopsy are performed at the same time. Children usually are given seda- tion or general anesthesia during the procedure to prevent discomfort. Upon awakening from sedation, your child may complain of bone pain at the bone marrow site; however, this pain is usually mild and resolves within 1–2 days. If your child is uncomfortable, a mild pain medication may be given.
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