Leukocytosis interference in clinical chemistry: shall we still interpret test results without hematological data?

Abstract

Summary Background Extreme leukocytosis is known to induce remarkable variations of some clinical chemistry tests, thus leading to possible clinical misinterpretation. This study aimed to define whether also moderate leukocytosis may influence the stability of glucose and blood gases. Methods Blood samples are sent to the local laboratory through a pneumatic tube system. Clinical chemistry testing is routinely performed using lithium-heparin tubes (for glucose) and heparin blood gases syringes (for blood gas analysis). Stability of glucose (in uncentrifuged blood tubes) and blood gases (in syringes) was hence evaluated in samples maintained at room temperature. Results were also analyzed in 2 subgroups of samples with different leukocyte counts, i.e., those with leukocytes <15 × 109/L and those with leukocytes >15 × 109/L. Results An accelerated decrease of pH was observed in blood gases syringes with leukocytosis (i.e., >15 × 109/L), while no difference was noted for other blood gases parameters (PCO2, PO2). Spurious and time-dependent hypoglycemia was noted in uncentrifuged blood tubes of patients with leukocytosis. Conclusions The results of our study suggest that even modest leukocytosis (i.e., around 15 × 109/L), which is frequently encountered in clinical and laboratory practice, may be associated with significant variations of both glucose and pH. This would lead us to conclude that results of these parameters shall be accompanied by those of hematologic testing to prevent clinical misinterpretation, namely with leukocyte counts.

Detection of preanalytical errors in arterial blood gas analysis

“…The practice of keeping glass syringes on ice is an old practice to slow down the metabolism and is no longer recommended for plastic syringes ( 1 , 3 ). The rate of cellular metabolism is much faster in patients with very high leukocytes or platelet counts ( 3 , 22 ). The cells in the whole blood use glucose and O 2 , produce CO 2 , hence decrease the pH and increase lactate due to continued glycolysis.…”

Investigation and Causes of Spontaneous (Non-Diabetic) Hypoglycaemia in Adults: Pitfalls to Avoid

“…Pitfalls to avoid are failure to recognise spurious hypoglycaemia and pseudohypoglycaemia. Spurious hypoglycaemia is a pre-analytical artefact due to either delayed separation of plasma from blood cells and incomplete inhibition of sample tube glycolysis or excessive in vitro glucose consumption due to leucocytosis, erythrocytosis or thrombocytosis [7,8]. Pseudohypoglycaemia has been used to describe falsely low finger prick capillary glucose values in patients with poor peripheral circulation [9].…”

"The Rising Importance of Pre-Analytical Phase in Medical and Research Laboratory, A New Challenge in the Omics Era"

“…Firstly, patient characteristics may influence pre analytical phase such as feeding state [1] or gender [2]. Physiological changes could promote some pre analytical events such as cell lysis in the form of hemolysis [3,4] or leukocyte lysis that could be related to the type and levels of blood cells or even some hematological disorders [5][6][7]. Physiological changes could also modulate other measurements such as calcium influenced by internal pH and albumin concentrations that could complicate medical interpretation and diagnosis [8,9].…”

“…In addition to experimental considerations to limiting sources of variation and the choice of instrumentation for analysis, pre analytical issues need to be carefully considered. The most studied metabolite, glucose, presents a classic case where its levels are influenced by physiological changes in the form of cell counts [5] or tube additives that modulate stability [14]. These findings on glucose may be extrapolated to substantial inconsistencies while performing large-scale metabolome analysis.…”