Establishment of reference intervals for hematological parameters of adult population in the western region of Saudi Arabia.

Background: Most of hematology laboratories in Saudi Arabia utilize the reference intervals (RIs) provided by instrument manufacturers. This study aimed to define RIs of hematological parameters for adult population in the western region of Saudi Arabia and to explore their specific features from an international perspective.

Method: This study was conducted according to the harmonized protocol of IFCC Committee on RIs and Decision Limits. Blood samples collected from 409 healthy Saudi males and females adults were analyzed for complete blood count (CBC) by using Cell-Dyn Sapphire analyzer and for iron profile by using Architect analyzers. The needs for RIs partitioned by sex and age was based on standard deviation ratio (SDR) and/or bias ratio (BR). RIs were derived parametrically with/without application of the latent abnormal values exclusion method (LAVE).

Results: Based on thresholds of SDR≥0.4 and/or BR≥0.57, RIs were partitioned by sex for red-blood cell count, hemoglobin, hematocrit, red cell distribution width, erythrocyte sedimentation rate, iron, transferrin, ferritin, eosinophil, platelet, plateletcrit, etc. Partitioning by age was not necessary for any of the analytes. LAVE procedure caused appreciable changes in RI limits for most erythrocyte and iron parameters but not for leukocyte parameters. Comparable to other non-IFCC studies on CBC RIs, the RBC and hematocrit (Ht) ranges have shifted to a higher side in both genders. After applying the LAVE method, the male and female RIs for Hb were 4.56 to 6.22 ×106/μL and 3.94 to 5.25 ×106/μL respectively while RIs for Ht were 40.2 to 52.0% and 33.6 to 44.5% respectively.

Conclusion: LAVE method contributed to reducing the influence of latent anemia in deriving RIs for erythrocyte related parameters. Using the up-to-date methods, the RIs of CBC determined specifically for Saudis will help to improve the interpretation of test results in medical decision making.