Evaluation of the Reticulocyte Production Index in the Pediatric Population
Fernando J Bracho1, Ignacio A Osorio1
1Laboratory of Hematology, Luis Calvo Mackenna Hospital, Santiago, Chile.
Insights
The traditional reticulocyte production index (RPI) is not suitable for children. An age-adjusted RPI (RPI/A) shows significant differences, impacting anemia diagnosis in pediatric patients.
Area of Science:
- Pediatric Hematology
- Clinical Pathology
- Diagnostic Accuracy
Background:
- Hematologic values, including reticulocyte counts, exhibit significant age-related variations in children.
- The traditional reticulocyte production index (RPI) may not accurately reflect erythropoietic activity in pediatric populations due to differing normal values.
Purpose of the Study:
- To evaluate the agreement between the traditional reticulocyte production index (RPI) and an age-adjusted RPI (RPI/A) in children.
- To assess the clinical implications of using RPI versus RPI/A in diagnosing anemia in pediatric patients.
Main Methods:
- A retrospective analysis of 5,503 complete blood counts (CBCs) from anemic children under 18 years old.
- Comparison of RPI values with an age-adjusted RPI (RPI/A) using theoretical age-specific normal values.
- Analysis of diagnostic discrepancies and clinical repercussions.
Main Results:
- No systematic error was found between RPI and RPI/A, but significant proportional differences were observed.
- RPI/A showed lower values in neonates (<15 days) and higher values in older children (≥15 days) compared to RPI.
- No age-based agreement was found between RPI and RPI/A, altering the diagnosis of aregenerative anemia, particularly in neonates.
Conclusions:
- The traditional RPI is inadequate for assessing bone marrow erythropoietic capacity in children.
- Age-specific normal hematologic values necessitate an age-adjusted index for accurate RPI assessment in pediatric anemia.
- RPI/A demonstrates improved accuracy for evaluating erythropoiesis in children, addressing limitations of the traditional RPI.
Objectives:
Since hematologic values vary with age in children, we evaluated the agreement between the "traditional" reticulocyte production index (RPI) and an RPI by age (RPI/A)-adjusted normal values.
Methods:
A retrospective, observational, and analytical study was performed on CBCs of children with anemia younger than 18 years. The agreement and clinical repercussions of the RPI values were analyzed with an RPI/A developed with theoretical values for different ages.
Results:
A total of 5,503 tests were analyzed and no systematic error between the two indices was found; however, there were significant proportional differences at higher values that resulted in lower RPI/A in children younger than 15 days and higher RPI/A in children aged 15 days and older. No agreement was observed at any age. The proportion of arregenerative anemia diagnosed using RPI/A was higher in children younger than 15 days and lower in those 15 days and older.
Conclusions:
RPI is not an adequate tool for evaluating the erythropoietic capacity of bone marrow in the pediatric population. The disagreement between the results can be explained by the difference in normal hematologic values between children and adults.
