From the Guidelines
A reticulocyte count is a crucial blood test for evaluating bone marrow function and diagnosing the cause of anemia, with a normal range of 0.5-2.5% of total red blood cells or 25,000-75,000 cells per microliter 1. The reticulocyte count is used to determine if the bone marrow is producing an appropriate number of red blood cells in response to anemia.
- An elevated retic count suggests the bone marrow is responding appropriately to blood loss or hemolysis by increasing red blood cell production.
- A low retic count indicates the bone marrow is not adequately producing new red blood cells, which may occur in conditions like aplastic anemia, certain nutritional deficiencies, or bone marrow failure. The test requires a simple blood draw and results are usually available within 24 hours.
- Clinicians often use the retic count alongside other blood tests like hemoglobin and hematocrit to diagnose the cause of anemia and monitor treatment effectiveness 1. In patients with chronic kidney disease (CKD), the reticulocyte count can help evaluate the appropriateness of the bone marrow response to anemia, with a low reticulocyte count suggesting insufficient erythropoietin production or inflammation 1. The reticulocyte count can also be used to classify anemia into different types, such as microcytic, normocytic, or macrocytic, based on the mean corpuscular volume (MCV) and reticulocyte count 1.
- For example, microcytic anemia with normal or low reticulocytes may indicate iron deficiency, while normocytic anemia with elevated reticulocytes may indicate hemolytic anemia. Overall, the reticulocyte count is a valuable tool for diagnosing and managing anemia, and should be used in conjunction with other laboratory tests and clinical evaluation to determine the underlying cause of anemia and guide treatment decisions 1.
From the Research
Retic Count
- Reticulocytes are the youngest erythrocytes released from the bone marrow into the blood and they circulate for 1-2 days before becoming mature erythrocytes 2.
- The reticulocyte count reflects the erythropoietic activity of bone marrow and is thus useful in both diagnosing anemias and monitoring bone marrow response to therapy 3.
- Reticulocyte parameters such as mean corpuscular volume of reticulocyte (MCVr), mean content hemoglobin of reticulocyte (CHr), and corpuscular hemoglobin concentration mean of reticulocyte (CHCMr) can be useful in differential diagnosis of anemias 2, 4.
Reticulocyte Parameters
- CHr is a good indication of iron availability and an early marker of iron deficient erythropoiesis which can be obtained readily using automated blood cell analyzers 5.
- CHr has a moderate sensitivity and specificity for diagnosing iron deficiency, and is less affected by inflammation than serum iron, transferrin saturation, and ferritin 5.
- MCVr and CHCMr can be useful in differentiating between iron deficiency anemia, vitamin B12 deficiency anemia, and mixed anemia 2, 4.
Clinical Utility
- Reticulocyte count and parameters can be a useful implement in the diagnosis of iron deficiency anemia and other anemias 4, 3.
- CHr is useful for early measurement of response to iron therapy, increasing within days of the initiation of iron therapy 5.
- Reticulocyte parameters can be used in screening of iron deficiency, diagnosis of iron deficiency anemia, and diagnosis of functional iron deficiency anemia in acute or chronic diseases or inflammation 5.