D-dimer reference values in the newborn

Objective: Understanding of developmental hemostasis is very important for the prevention, diagnosis and treatment of thrombotic diseases and bleeding disorders in newborns. It is known that coagulation and fibrinolytic system markers are high after birth and reach adult levels over time. In addition, test results vary depending on the device and reactants used. Therefore, it is recommended that each laboratory establish its own age-specific reference ranges. In this study, we aimed to determine the D-dimer reference values ​​in the neonatal period. Materials and Methods: The study was conducted in the Obstetrics and Obstetrics clinic and neonatal outpatient clinic of a third level hospital. Completely healthy term babies of 1-28 days without any pathological findings in prenatal, natal and postnatal periods were included in the study. In addition to D-dimer, whole blood, PT, aPTT, INR, and CRP were studied in all babies. Results: 134 term newborns were included in the study. 71 of the babies were boys and 63 were girls. Mean D-dimer levels of 1-28 days old babies were determined as 1.74±1.88 mg / L, reference range (0.25-2.81mg / L). Weekly D-dimer levels are 2.44-2.45mg / L, 1.71-1.76mg / L, 1.26-0.89 mg / L and 0.88-0.66 mg for the first 4 weeks, respectively. / L. It was observed that D-dimer values ​​decreased with the postnatal day (r: -0.31 p <0.001) but the average was above adult levels even in the last week in the neonatal period. There was no statistically significant difference in D-dimer values ​​between female (1.93±2.06) and male (1.57±1.71) babies. PT (12.7±2.3 s), aPTT (33.5±8 s) levels were found to be compatible with the literature. Discussion: D-dimer levels were found higher in the neonatal period than in adults. D-dimer levels were found to decrease over time in the first month. It is appropriate to use reference values ​​based on the calendar age when interpreting coagulation tests in newborns.