Impactos da carbamilação e da icterícia induzidas in vitro sobre a quantificação de parâmetros laboratoriais associados à coagulação sanguínea

Abstract

Hemostasis is a process highly regulated by pro-coagulant and anticoagulant proteins with the purpose of maintaining blood flow within the vessels and capable of promoting coagulation when there is vascular damage. Changes in different stages of hemostasis predispose to diseases that lead to hemorrhage, as in hemophilia, or to thrombotic events and can be diagnosed through the analysis of parameters that evaluate the individual's coagulation. For the results from the coagulation tests to be carried out correctly, error factors must be avoided. Interferents such as lipemia, icterus and hemolysis are possible sources that can generate results that are incompatible with reality because they cause changes in the analysis. Another factor that can affect the result of laboratory tests is the structural alteration of coagulation proteins. One of these changes comes from the carbamylation reaction that occurs in amino acids, peptides and proteins, affecting its function and predisposing to some pathologies. Carbamylation occurs in the body mainly due to the presence of cyanate due to urea metabolism and the action of myeloperoxidase in inflammatory processes on thiocyanate and can affect proteins involved in hemostasis. Although some studies have already been developed, research that better evaluates the possible interference of icterus in the determination of D-dimer and protein carbamylation in the evaluation of coagulation parameters are still necessary for a better evaluation of the patient and understanding of interferences in hemostasis. In this first study, the interference of icterus in the D-dimer analysis was evaluated through the addition of commercial D-dimer control and different concentrations of bilirubin (0, 0.9, 1.9, 3.8, 7.5, 15 and 30 mg/dL) to human plasma pools, followed by D-dimer quantification by immunoturbidimetric assay. Carbamylation was analyzed by exposing comercial controls and plasma pools to different concentrations of potassium cyanate (0, 150 nm, 150 μM, and 150 mM) and urea (0, 20, 100, and 500 md/dL) with subsequent analysis of coagulation parameters: prothrombin time (PT), activated partial thromboplastin time (aTTP), and fibrinogen. Through the studies performed, it can be verified that icterus does not seem to interfere in the analysis of D-dimer. The carbamylation experiments with KOCN showed a significant increase in TP and aTTP and reduction in fibrinogen in the commercial controls, while in plasma the changes in the tests occurred at the highest concentration of cyanate, except for TP, which also elevated at the 150 μM KOCN concentration. Incubation with increasing concentrations of urea prolonged the PT and aTTP in the commercial controls. In plasma, such evidence occurred only at the highest urea concentration. Fibrinogen was not shown to be affected by incubation with urea. The observed changes may indicate that patients with inflammatory processes and chronic kidney disease could develop hemostatic disorders.