When a child is being evaluated for acute lymphoblastic leukaemia (ALL), the diagnosis does not usually come from a single test. Before a doctor knows what is causing a child's symptoms, he or she often needs information from various tests and examinations, such as blood tests, bone marrow examination, imaging scans, and other investigations. Although this process can be daunting for families, every test helps answer a question and gets doctors closer to a correct diagnosis.
It can begin with a blood test
Many kids are the first to notice it in a routine blood checkup. A child can feel very tired, get a lot of infections, bruise easily, have very pale skin, or have a fever that does not go away. A blood test can determine if there are too many or too few blood cells.
Typically, doctors will examine:
Red blood cells
White blood cells
Platelets
Blood tests can reveal abnormal blood counts and the presence of immature blood cells (blasts), which may raise suspicion of ALL and lead to further testing.
The bone marrow test
The most definitive test is a bone marrow exam. Blood cells are produced in the soft tissues of the bones known as bone marrow. The surgeon, during the procedure, takes a small amount of bone marrow, typically from the hip bone.
The sample is then analysed in the lab to determine if there are any leukaemia cells. This test is useful for doctors to:
Confirm the diagnosis
The type of leukaemia
Determine the extent of the bone marrow involvement
Lumbar Puncture
Physicians might suggest a lumbar puncture (spinal tap) if ALL is found. During this procedure, the doctor removes a small sample of fluid from around the brain and spinal cord for analysis. The aim is to determine if leukaemia cells have spread to the central nervous system. The idea of the procedure may sound frightening, but it is something that is commonly part of the diagnosis and treatment planning of childhood ALL.
Genetic and molecular testing
ALL is not the same for everyone. Doctors sometimes use specialised laboratory tests to examine leukaemia cells for gene changes and chromosome abnormalities.
These tests help:
Recognize ALL subtypes
Forecast disease action - the likely trends of disease action
Guide treatment decisions
Identify if targeted therapies are beneficial
The data can be used to help develop an individualised care plan.
Imaging scans
Scans are typically not used to make a diagnosis of ALL, but sometimes can be very helpful. Depending on the child's symptoms, doctors may order:
Chest X-rays
CT scans
MRI scans
Ultrasound scans
These tests can detect any enlargement of organs, swollen lymph nodes, or changes associated with the disease.
Additional blood tests
There are a few more blood tests that may be done for children with ALL. These tests can assist your doctor in evaluating:
Liver function
Kidney function
Blood levels of some chemicals
Pre-treatment general health status
The implications are that the results will aid in the safe planning of treatment.
Understanding the results
Childhood ALL diagnosis is a process of steps. One test might point to a problem, the other one to the details. Blood and bone marrow tests can be used to raise questions, genetic studies can help clarify the disease, and bone marrow tests can help confirm the diagnosis. Waiting for test results can be stressful, but all tests have a reason. They work together to provide the doctor with a full picture of the child's situation and to help plan the best possible treatment.