Reticulocytes

Specimen Required

3cc EDTA BLOOD (CBC VIAL)

Fasting Required

Purpose of the Test

To help evaluate the bone marrow’s ability to produce red blood cells (RBCs) and to help distinguish between anaemia related to blood loss or destruction and anaemia related to decreased RBC production; to help monitor bone marrow response and the return of normal marrow function following chemotherapy, bone marrow transplant, or post-treatment follow-up for iron deficiency anaemia

When this test is required

A reticulocyte count may be requested when you have a decreased RBC count and/or a decreased haemoglobin and haematocrit and your doctor wants to evaluate bone marrow function. If you have no apparent symptoms, these findings may be found during routine blood testing. Reticulocyte count may also be used when you have symptoms such as paleness, tiredness, weakness, shortness of breath, and/or blood in the stool.A Reticulocyte count is useful after a recent episode of blood loss or in cases where the lifespan of red cell is shortened as seen in some haemolytic anaemia.Reticulocyte count may also be used when you have a known iron or vitamin vitamin B12 or folate deficiency, known kidney disease, known bone marrow suppression as may occur during chemotherapy or bone marrow transplant. Reticulocyte count may be requested with a RBC count, haematocrit, and haemoglobin at intervals recommended by your doctor to monitor marrow function and response to treatment.When you have an increased number of RBCs and elevated haemoglobin and haematocrit, the reticulocyte count may be used to help work out the degree and rate of overproduction of RBCs.

What the Test Detects

Reticulocytes are immature red blood cells (RBCs). They are produced in the bone marrow when stem cells differentiate and progress toward RBC development, eventually forming reticulocytes and finally mature RBCs. Most RBCs are fully mature before they are released from the bone marrow into the blood, but about 0.5 – 2% of the RBCs in circulation will be reticulocytes. This test measures the number and percentage of reticulocytes…Reticulocytes are immature red blood cells (RBCs). They are produced in the bone marrow when stem cells differentiate and progress toward RBC development, eventually forming reticulocytes and finally mature RBCs. Most RBCs are fully mature before they are released from the bone marrow into the blood, but about 0.5 – 2% of the RBCs in circulation will be reticulocytes. This test measures the number and percentage of reticulocytes in the blood and serves as an indicator of the adequacy of bone marrow red blood cell (RBC) production. Normal RBCs have a lifespan of about 120 days. The body attempts to maintain a stable number of RBCs in circulation by continually removing old RBCs and producing new ones in the bone marrow. If this steady state is disrupted by an increased loss of RBCs or by decreased production, then anaemia will develop. Increased loss of red blood cells may be due to severe and short term (acute) or chronic bleeding haemorrhage) or haemolysis. The body compensates for this loss by increasing the rate of RBC production. When this happens, the number and percentage of reticulocytes in the blood increases until a sufficient number of RBCs is present and the balance is restored or until the production capacity of the marrow is reached. Decreased RBC production may occur when the bone marrow is not functioning normally, due to a bone marrow disorder such as aplastic anaemia or due to marrow suppression from a variety of causes including radiation and chemotherapy treatments for cancer, because of insufficient erythropoietin, or because of deficiencies in certain nutrients such as iron, vitamin B12, or folate. This decreased production leads to fewer RBCs in circulation, decreased haemoglobin and oxygen-carrying capacity, a lower haematocrit, and to a reduction in the number of reticulocytes as old RBCs are removed from the bloodstream, but not fully replaced. Occasionally, both the reticulocyte count and the RBC count will be increased because of excess RBC production. This may be due to a variety of causes including inappropriately increased production of erythropoietin, disorders that chronically produce increased numbers of RBCs (polycythemia vera), and cigarette smoking. How is the sample collected for testing? A blood sample is obtained by inserting a needle into a vein in the arm or sometimes from pricking a finger or the heel of an infant. Is any test preparation needed to ensure the quality of the sample? No test preparation is needed. Blood sample can be collected at any time of the day, before or after a meal. See MoreSee Less

Preparation for the Test

No test preparation is needed. Blood sample can be collected at any time of the day, before or after a meal.

Sample Requirements

A blood sample obtained by inserting a needle into a vein in the arm or sometimes from pricking a finger or the heel in the case of infants.Test samples are collected into sample tubes containing EDTA preservatives.

Additional Notes

Patients who move to higher altitudes may have increased reticulocyte counts as their body adapts to the lower oxygen content of their new location. Smokers also may demonstrate an increased number of RBCs and reticulocytes.Reticulocyte counts may be increased during pregnancy. Newborns have a higher percentage of reticulocytes, but the number drops to near adult levels within a few weeks.Traditionally, reticulocyte counts have been done manually by looking at a specially stained slide under the microscope and counting the number of reticulocytes in a number of fields of view. This method is still in use, but it is in the process of being replaced by automated methods that allow for a greater number of cells to be counted, thus enhancing the accuracy of reticulocyte counts.

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