Specific microRNAs for Heart Failure: Reference Values in Whole Blood.

Background: The objective of this study was to validate reference values for eight selected microRNAs (miRNAs) in a population of healthy individuals. The selected miRNAs (hsa-miR-21-5p, hsa-miR-23a-3p, hsa-miR-142-5p and hsa-miR-126-3p, hsa-miR-499a-5p, hsa-miR-195-5p, hsa-miR-1-3p, hsa-miR-29a-3p) have an important role in heart failure. Methods: Ninety-nine individuals were selected for this study. Specific microRNAs were isolated from whole blood and quantified using the microRNA enzymatic immunoassay (miREIA) method. Reference intervals were evaluated with respect to age and sex. Statistical analyses were performed using MedCalc (v22.021) and R software, Version 4.1.2. Results: Reference values (2.5th and 97.5th percentile values and their 90% confidence intervals) were determined for hsa-miR-21-5p: 1.45 to 96.3 pmol/L, hsa-miR-23a-3p: 13.0 to 432 pmol/L, hsa-miR-126-3p: 5.67 to 66.5 pmol/L, hsa-miR-142-5p: 37.4 to 293 pmol/L, hsa-miR-195-5p: 11.5 to 254 pmol/L, hsa-miR-1-3p: 50.6 to 1800 pmol/L, hsa-miR-499a-5p: 8.90 to 82.5 pmol/L and hsa-miR-29a-3p: 22.9 to 210 pmol/L. The median age of the included individuals was 44 years (range: 23-75 years). No sex-related differences were observed in the reference intervals of the microRNAs (p < 0.05). Except for hsa-miR-21-5p (RS = -0.208; p = 0.043), no significant age-related associations were found for the other microRNAs (p < 0.05). However, due to the limited number of individuals in the stratified subgroups, reference intervals were not calculated for these subgroups. Conclusions: In this study, reference intervals for eight specific miRNAs associated with heart failure were determined. The results are unique for assessment in further clinical research, given that reference intervals in absolute values have not yet been published.