Evaluation of the Prothrombotic Risk Factors in Children with Leukemia

Pediatric patients with malignancy are at high risk of thromboembolic complications due to complex interactions of a variety of factors such as the malignancy, chemotherapy, central venous catheters (CVCs), infections, dehydration, and hereditary thrombophilia. In this study, deficiencies of protein C (PC), protein S (PS), and antithrombin (AT), activated protein C resistance (APCR), the factor V G1691A mutation, the prothrombin G20210A mutation, and increased factor VIII, IX, fasting homocysteine levels were assessed at the diagnosis of leukemia, retrospectively. The aim was to evaluate the role of the thrombophilic risk factors on vascular events during treatment period. Thirty children (11 F, 19 M) with leukemia (24 patients with ALL, 4 AML, one biphenotypic leukemia, one infant leukemia) were enrolled in this study. The median age of the patients was 56 months (range 7–215 months). All patients had CVCs, and thromboprophylaxis was not given to the any patients. We detected main prothrombotic risk factors at the diagnosis of leukemia as following: low PC (8/30), PS (11/30), AT activity (3/25), APCR (5/22), increased FVIII (5/22), FIX (2/22), and homocysteine levels (2/8), and FV Leiden mutation (1/24; heterozygous). The prothrombin G20210A mutation was not detected in any patient. The parents of these patients with abnormal test results were also evaluated to discriminate congenital or acquired deficiencies. In addition; PC, PS, AT levels were followed-up, and MTHFR genotype for the patients with high homocysteine levels was studied, also. In spite of, 24 of these 30 patients had at least one abnormal laboratory test result at the diagnosis of leukemia, venous thrombosis (7 with CVC-related venous thrombosis, one CVC-related jugular vein thrombosis and VOD, one vena saphena parva thrombosis) developed in 9 of 24 patients. In conclusion, leukemic children with at least one prothrombotic risk factor have high venous thrombosis risk. Further trials are needed to clarify the necessarity of screening program for thrombophilia and thromboprophylaxis in children with leukemia and CVCs, and, especially for the patients carrying hereditary prothrombotic risk factors.