Defining Reference Intervals for Complete Blood Count and Micronutrient Parameters in Urban Bangladeshi Population

With a lack of population-specific reference intervals (RIs) in Bangladesh, this study aimed to determine RIs for complete blood count (CBC) and specific micronutrients, vitamin D (VitD) and zinc, and to assess the possible impact of prior history of SARS-CoV-2 infection on these parameters. Healthy participants (n = 1724) of both sexes aged ≥ 10 years from slum and non-slum areas of Dhaka city were sampled systematically. A total of 26 CBC parameters were determined using an automated hematology analyzer, whereas the micronutrients VitD and zinc were measured using automated immunoassay analyzers and atomic absorption spectrophotometry (AAS), respectively. Multiple regression analysis (MRA) was employed to determine the association of variations in reference values (RVs) of hematological and micronutrient parameters with sex, age, and slum residency of the participants. Practical significance of each factor was judged from partial correlation coefficients (r_p) by setting its minimum effect size at |r_p| = 0.2. The need to partition RVs by sex and age was assessed using the ANOVA-based standard deviation ratio (SDR). RIs were determined by parametric method after Gaussian transformation using the two-parameter Box–Cox formula, with or without the latent abnormal values exclusion (LAVE) method. By MRA, sex and age were significant source of variations for various CBC parameters, whereas slum residence was associated with increased levels of VitD and zinc Using the SDR ≥ 0.35 threshold, RVs were partitioned by sex to derive RIs for hemoglobin, hematocrit, red cell count and indices (MCH, MCHC), and plateletcrit, as well as for VitD and zinc. Comparing these RIs with those from the global collaborative studies indicated significant differences in erythrocyte and leukocyte parameters. These are the first population-specific RIs for urban Dhaka city, underscoring the need for country-specific RIs for accurate clinical use.