title: Indirect determination of pediatric blood count reference intervals.
abstract: BACKGROUND
  Determination of pediatric reference intervals (RIs) for laboratory quantities, including hematological quantities, is complex. The measured quantities vary by age, and obtaining samples from healthy children is difficult. Many widely used RIs are derived from small sample numbers and are split into arbitrary discrete age intervals. Use of intra-laboratory RIs specific to the examined population and analytical device used is not yet fully established. Indirect methods address these issues by deriving RIs from clinical laboratory databases which contain large datasets of both healthy and pathological samples.
  
  
  METHODS
  A refined indirect approach was used to create continuous age-dependent RIs for blood count quantities and sodium from birth to adulthood. The dataset for each quantity consisted of 60,000 individual samples from our clinical laboratory. Patient samples were separated according to age, and a density function of the proportion of healthy samples was estimated for each age group. The resulting RIs were merged to obtain continuous RIs from birth to adulthood.
  
  
  RESULTS
  The obtained RIs were compared to RIs generated by identical laboratory instruments, and to population-specific RIs created using conventional methods. This comparison showed a high concordance of reference limits and their age-dependent dynamics.
  
  
  CONCLUSIONS
  The indirect approach reported here is well-suited to create continuous, intra-laboratory RIs from clinical laboratory databases and showed that the RIs generated are comparable to those created using established methods. The procedure can be transferred to other laboratory quantities and can be used as an alternative method for RI determination where conventional approaches are limited.
authors: Department of Pediatrics, University of Erlangen-Nuremberg, Erlangen, Germany.
authors: Jakob
authors: J
authors: Zierk
authors: Farhad
authors: F
authors: Arzideh
authors: Rainer
authors: R
authors: Haeckel
authors: Wolfgang
authors: W
authors: Rascher
authors: Manfred
authors: M
authors: Rauh
authors: Markus
authors: M
authors: Metzler
mesh_terms: D000293:Adolescent; D001772:Blood Cell Count / Q000592:standards*; D002648:Child; D002675:Child, Preschool; D004906:Erythrocyte Count / Q000592:standards; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis / Q000592:standards; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007958:Leukocyte Count / Q000592:standards; D008297:Male; D010976:Platelet Count / Q000592:standards; D012016:Reference Values; D012964:Sodium / Q000097:blood / Q000592:standards
chemical_list: D006454:Hemoglobins; D012964:Sodium