Myelodysplastic syndromes (MDS) can be difficult to diagnose. Several other diseases closely resemble these syndromes and can be confused with MDS, including:
- aplastic anemia
- certain leukemias, including acute leukemias, NK leukemia, and NK T cell leukemia
- HIV infection
- an overactive immune system
- other chronic medical diseases
Many people who are diagnosed with MDS go to their physicians with some or all of the symptoms typical of the condition. Other people are diagnosed with MDS after they go to their physician for a routine checkup and mild blood-count abnormalities that have not caused any symptoms are found in their blood work.
Proper diagnosis is crucial so that you receive the most-effective treatment for MDS. Often, you will be referred to a hematologist, but a definitive diagnosis can only be provided when a hematopathologist examines a bone marrow sample.
Blood Tests That Can Show Someone Has MDS
A very basic blood test called a CBC (complete blood count) can be performed to see whether the numbers of various types of blood cells are within normal ranges. This is a routine test that is usually done as part of your regular medical checkup or prior to having a surgical procedure.
Abnormalities in this test provide the first sign that someone may have an MDS. In these syndromes, red blood cell levels may be low, causing anemia; platelet levels may be low, which can cause bleeding and bruising; and white blood cell levels may be diminished, leading to infections.
A hematologist will also look at your blood sample under the microscope in a test called a blood smear to identify any abnormal cell shapes and sizes, which can also indicate that you have MDS.
In addition, tests will be done to look for other causes of low blood counts, including thyroid disease, low vitamin levels, and iron deficiency.
Bone Marrow Tests to Diagnose MDS
Samples of bone marrow are needed to make the diagnosis of MDS when the blood tests do not show the reason for the abnormal blood counts. Two types of samples are taken. One is called a bone marrow biopsy, which is obtained by removing a small piece of the bone along with the marrow inside the bone. The second is called a bone marrow aspirate, which is obtained by drawing out a sample of liquid from the bone marrow space.
Many tests are performed on the bone marrow biopsy and aspirate samples. These tests will help to confirm the diagnosis of MDS (for example, by showing that the cells look abnormal, or dysplastic), to determine which subtype of MDS you have, and to help your physician determine the most-effective treatment and prognosis.
Tests that are performed on bone marrow samples include:
Cytogenetic studies — These studies help to determine chromosome changes in bone marrow cells. Each cell in the body contains chromosomes (46 tightly coiled strands of DNA). Chromosomes contain all the information that cells need to function normally. In about half of patients with MDS, one or more chromosomal changes can be identified. The most common abnormalities are seen in chromosomes 5, 7, 8, and 20.
Histochemistry studies — Physicians look at the bone marrow cells to determine whether the cells look abnormal (or dysplastic). With these tests, the bone marrow blast count can also be determined, and the pathologist can look for other causes of bone marrow malfunction.
Flow cytometry — Cells are passed through a laser beam for analysis to see whether the bone marrow cells are developing normally and to obtain an estimate of the blast count.
Molecular genetic studies — Highly sensitive DNA and RNA tests are conducted to determine the specific genetic traits of the bone marrow cells.
New diagnostic tests and procedures are emerging as a result of research performed in the laboratories at Memorial Sloan-Kettering and at other institutions. Your physician may ask whether you would be willing to have additional blood or bone marrow samples taken for this type of research.
These tests are not necessary to make a diagnosis of MDS, and they are not required tests. However, research on samples taken from people with MDS is vital to our ongoing efforts to learn more about MDS and to develop better treatments. Talk with your Memorial Sloan-Kettering physician to learn more about such studies.