We are often asked why we track the Reticulocyte % in the Functional Health Report but not the Reticulocyte Absolute Count. This short article will discuss our reasonings.
What Are Reticulocytes?
First off, we should refresh your memory on what exactly reticulocytes are. Reticulocytes are young, immature red blood cells recently released from the bone marrow into the bloodstream. They still contain RNA remnants, giving them their characteristic “reticulated” appearance when stained and viewed under a microscope.
Why Test for Reticulocytes?
Testing reticulocytes helps assess how effectively the bone marrow produces and releases new red blood cells, making it a valuable indicator of overall erythropoietic health. If someone has anemia or is suspected of having an issue related to blood cell production or destruction, measuring the reticulocyte level can help determine whether the problem lies in underproduction, excessive loss, or increased destruction of red blood cells.
Why We Track the Reticulocyte % and not the Reticulocyte Absolute Count
When deciding between tracking Reticulocyte % (retic %) versus the Absolute Reticulocyte Count, there are several reasons why the percentage metric often proves more practical and clinically meaningful in a functional health context:
1. Ease of Interpretation Relative to Overall RBC Population:
The reticulocyte percentage directly shows what fraction of the total red blood cell population is newly produced. Since reticulocytes are essentially immature red blood cells that have recently been released from the bone marrow, the percentage helps you understand the marrow’s relative output in the context of the existing RBC mass. This direct comparison makes it easier to gauge bone marrow responsiveness without additional calculations.
2. Quick Insight into Changes in RBC Production:
The retic % can shift more rapidly in response to changes in erythropoiesis (red blood cell production) and blood loss or hemolysis. Because it’s a ratio, changes in RBC turnover (due to acute bleeding, for example) will be more readily apparent. This can give an early and sensitive signal of the bone marrow’s reaction to physiological stressors.
3. Widespread Clinical Familiarity and Standardization:
Reticulocyte percentage is a routinely reported parameter in standard complete blood counts (CBCs) with differential tests and is well-established in medical practice. Reference ranges for retic % are widely recognized, making results more readily interpretable without extensive additional calculations.
4. Practical in a “Functional” Context:
In many functional health or integrative settings, the goal is often to quickly assess whether someone’s bone marrow appropriately compensates for blood system demands. Since retic % correlates directly with the state of RBC turnover relative to the total RBC population, it is more intuitively aligned with assessing overall functional status. It allows practitioners to track improvements or declines in blood-building capacity over time using a single, straightforward metric.
5. No Need for Concurrent RBC Counts:
Absolute reticulocyte count calculation requires accurate RBC counts to yield meaningful data. If RBC counts fluctuate or if there’s difficulty ensuring accurate RBC enumeration, the absolute count can become less reliable. Since retic % is directly measured as a proportion of RBCs, it remains stable and interpretable even if RBC counts vary somewhat.
Summary
In summary, Reticulocyte % offers a more intuitive, readily interpretable, and widely recognized measure of red blood cell production dynamics, making it a practical choice for ongoing Functional Health Assessments.
