An unusual case of sodium citrate-dependent artifactual platelet count

Variations in the full blood count parameters among apparently healthy humans in the Ho municipality using ethylenediamine tetraacetic acid (EDTA), sodium citrate and lithium heparin anticoagulants: A laboratory-based cross-sectional analytical study

Background

Several studies have shown that various anticoagulants used for collection of blood samples produce varying effects on haematological analyses. Tripotassium ethylenediamine tetra-acetic acid (K₃EDTA), sodium citrate and lithium heparin remain the most used anticoagulants employed in hematological analysis. There is paucity of data on the effect of these anticoagulants on haematological parameters in humans in Ghana. We assessed the suitability of K₃EDTA, sodium citrate and lithium heparin for routine Full Blood Count (FBC) investigation.

Method

A laboratory-based analytical cross-sectional study was conducted using blood samples from 55 conveniently sampled apparently healthy tertiary students from January 2021 to October 2021. Blood samples were taken from each participant into 3 anticoagulant tubes: K₃EDTA, sodium citrate and lithium heparin and FBC parameters estimated using the Mindray automated haematology analyzer. One-way ANOVA Kruskal-Wallis test, Mann-Whitney U, Intra-class correlation coefficient (ICC) analysis, Bland-Altman's plot and Lin's concordance correlation coefficient were used where appropriate to ascertain the level of variation, consistency, and agreements among and between results. Normality testing using Shapiro-Wilk test statistic revealed non-Gaussian distribution of data, hence, were presented as median, minimum, and maximum. Data generated were analyzed using STATA v15 and MedCalc v20 where appropriate for statistical analysis. P-values <0.05 were considered statistically significant.

Results

The study comprised 34 males and 21 females. The median age for males (23 years: min = 20, max = 34) was statistically comparable (p = 0.2652) to that of females (22 years: min = 18, max = 34). We observed excellent consistency in the estimation of MCV (ICC = 0.94), MCH (ICC = 0.98), MCHC (ICC = 0.91), GRAN# (ICC = 0.92) and LYMPH% (ICC = 0.91) across the three anticoagulants. Heparin and K₃EDTA largely agreed on most of the FBC parameters, 50.0% (7/14) including HGB, MCV, MCH, PLT, LYMPH#, GRAN# and GRAN%. Meanwhile using K₃EDTA as a standard, heparin produced almost perfect agreement only in the assessment of RBC (CCC = 0.992) while a substantial agreement was observed in the assessment of HGB (0.971), HCT (0.958) and MCH (0.987). Citrate agreed substantially with K₃EDTA in the assessment of LYMPH% (CCC = 0.964) and moderately in the assessment of MCV (CCC = 0.948) and MCH (0.913). Overall, compared to K₃EDTA, heparin was highly precise and accurate in the estimation of HGB, RBC, HCT and MCH while citrate determined MCV and MCH more accurately and precisely.

Conclusion

Citrated blood consistently produced lower FBC values compared to heparin and K₃EDTA and hence suggests not reliable in the assessment of FBC among humans. Heparin agreed largely with K₃EDTA in the estimation of FBC parameters and may be used as a better alternative anticoagulant in the absence of K₃EDTA however with great caution.

Influence of different methods and anticoagulants on platelet parameter measurement

Platelets are the smallest and perhaps the most versatile components of human blood. Besides their role in coagulation and the maintenance of vascular integrity, they are involved in many physiological processes, ranging from immune response and leukocyte recruitment to the production of antimicrobial peptides and immune-suppressive factors like TGF-β. These versatile abilities make platelets interesting for researchers from different disciplines. However, beside profound investigation into platelets’ physiological role, there is a need for correct, standardized and thus reproducible quantification of platelet parameters. Mean platelet volume (MPV) is a widespread prognostic marker for several conditions, such as, acute coronary syndrome, chronic kidney disease and liver cirrhosis. Platelet activation is regarded as a marker for inflammatory processes, for example in autoimmune diseases such as type-1 diabetes, systemic lupus erythematosus and rheumatoid arthritis. The monitoring of platelet function is relevant for patients receiving antiplatelet medication. Platelet parameter measurement is affected by the choice of in vitro anticoagulant, the measurement technology and the time delay after sampling. This review focuses on the pre-analytical variability that arises as a result of the use of different in vitro anticoagulants and analyzer technologies when determining platelet parameters, since, even approximately 180 years after the discovery of platelets, there is still no standardized procedure.