title: [Investigation of reference intervals of blood gas and acid-base analysis assays in China].
abstract: OBJECTIVE
  To investigate and analyze the upper and lower limits and their sources of reference intervals in blood gas and acid-base analysis assays.
  
  
  METHODS
  The data of reference intervals were collected, which come from the first run of 2014 External Quality Assessment (EQA) program in blood gas and acid-base analysis assays performed by National Center for Clinical Laboratories (NCCL). All the abnormal values and errors were eliminated. Data statistics was performed by SPSS 13.0 and Excel 2007 referring to upper and lower limits of reference intervals and sources of 7 blood gas and acid-base analysis assays, i.e. pH value, partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2), Na+, K+, Ca2+ and Cl-. Values were further grouped based on instrument system and the difference between each group were analyzed.
  
  
  RESULTS
  There were 225 laboratories submitting the information on the reference intervals they had been using. The three main sources of reference intervals were National Guide to Clinical Laboratory Procedures [37.07% (400/1 079)], instructions of instrument manufactures [31.23% (337/1 079)] and instructions of reagent manufactures [23.26% (251/1 079)]. Approximately 35.1% (79/225) of the laboratories had validated the reference intervals they used. The difference of upper and lower limits in most assays among 7 laboratories was moderate, both minimum and maximum (i.e. the upper limits of pH value was 7.00-7.45, the lower limits of Na+ was 130.00-156.00 mmol/L), and mean and median (i.e. the upper limits of K+ was 5.04 mmol/L and 5.10 mmol/L, the upper limits of PCO2 was 45.65 mmHg and 45.00 mmHg, 1 mmHg = 0.133 kPa), as well as the difference in P2.5 and P97.5 between each instrument system group. It was shown by Kruskal-Wallis method that the P values of upper and lower limits of all the parameters were lower than 0.001, expecting the lower limits of Na+ with P value 0.029. It was shown by Mann-Whitney that the statistic differences were found among instrument system groups and between most of two instrument system groups in all assays.
  
  
  CONCLUSIONS
  The difference of reference intervals of blood gas and acid-base analysis assays used in China laboratories is moderate, which is better than other specialties in clinical laboratories.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000136:Acid-Base Equilibrium; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000032:analysis; D002681:China; D006801:Humans; D010100:Oxygen / Q000032:analysis; D010313:Partial Pressure; D012016:Reference Values; D012107:Research Design
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen