Reference Intervals For D-dimer Research Articles

The D-dimer reference intervals in healty term newborns

ObjectiveTo determine the D-dimer reference intervals in the neonatal period. Materials and methodsThe research had been carried out in the obstetrics and gynecology clinic and neonatal outpatient clinic of a third level hospital. Healthy term newborns aged between 1 and 28 days were enrolled in the study. Venous blood samples were collected from peripheral veins in all babies and D-dimer, prothrombin time, activated partial thromboplastin time and platelet counts were measured. Reference intervals for D-dimer in the neonatal period were determined using 2.5th and 97.5th percentile values. ResultsA hundred and thirty four newborns (71 boys, 63 girls) were enrolled in the study. Mean D-dimer levels of infants aged 1–28 days was 1.74 ± 1.88 mg/L (reference range; 0.25–2.81 mg/L). D-dimer levels were between 2.44 and 2.45 mg/L, 1.71–1.76 mg/L, 1.26–0.89 mg/L and 0.88–0.66 mg/L in the first, second, thirth and fourth week of life,respectively. D-dimer values inversely correlated with postnatal age (r:−0.3, p < 0.001). However, it remained above adult levels even in the last week. There was no statistically significant difference between the D-dimer levels of girls (1.93 ± 2.06 mg/L) and of boys (1.57 ± 1.71 mg/L). DiscussionIn this study, D-dimer levels in the neonatal period were found to be higher than adult levels stated in the literature. D-dimer levels gradually decreased overtime in the first month. It would be appropriate to use age-specific reference values in the evaluation of D dimer levels in the neonatal period.

Pregnancy-adjusted D-dimer reference intervals derived from electronic medical records

Pregnancy-adjusted D-dimer reference intervals derived from electronic medical records

Reference intervals for D-dimer and fibrinogen in the Chinese population during the third trimester of pregnancy

Reference intervals for D-dimer and fibrinogen in the Chinese population during the third trimester of pregnancy

Effect of Using an Age-adjusted D-dimer to Assess for Pulmonary Embolism in Community Emergency Departments.

The objective of this study was to evaluate the effect of changing the laboratory-reported D-dimer reference intervals to age-adjusted reference intervals on the use of advanced chest imaging and 30-day adverse events among emergency department (ED) encounters. A retrospective interrupted time-series analysis of ED encounters for patients >50years evaluated for suspected pulmonary embolism (PE) from April 2014 to April 2016. The primary outcome was use of advanced diagnostic imaging, and the secondary outcome was 30-day mortality or PE diagnosis. Secondary analyses also quantified delayed PE diagnoses pre- and postintervention. A generalized estimating equation segmented logistic regression model, adjusting for patient and facility characteristics, was used to determine changes in odds of diagnostic imaging and 30-day mortality or PE diagnoses. A total of 10,534 (5,153 pre- and 5,381 postimplementation) ED encounters were included. Advanced imaging was obtained in 35.9% of pre- versus 33% of postimplementation encounters. Age-adjusted D-dimer (AADD) showed a small and nonsignificant decrease in month-to-month trends of advanced chest imaging postimplementation (odds ratio [OR]= 0.98, 95% confidence interval [CI]= 0.96 to 1.00). Use of advanced imaging in patients with D-dimer values lower than 500ng/mL fibrinogen-equivalent units (FEU) was similar in the preintervention (5.8%) and postintervention (6.8%) periods. However, imaging was obtained in 30% of patients postintervention with a D-dimer result less than AADD reference interval , but more than the historical 500ng/mL FEU reference interval. Implementing an AADD threshold demonstrated no change in the rate of 30-day adverse events (missed PE or mortality). Changing the laboratory-reported D-dimer reference intervals for evaluation of PE was not associated with reduction in advanced chest imaging and did not increase 30-day adverse events. However, there was substantial noncompliance with the age-adjusted reference intervals in the postintervention period likely blunting the impact of this intervention.

D-dimer during pregnancy: establishing trimester-specific reference intervals

Pregnancy is associated with an increased risk of venous thromboembolism (VTE). D-dimer is a biomarker used as an exclusion criterion of VTE disease, but its usefulness during pregnancy shows limitations because D-dimer levels physiologically increase through pregnancy. The aim of our study was to follow the changes of D-dimer levels and to establish trimester-specific reference intervals during normal pregnancy. This is a longitudinal prospective study in which the reference population finally included 102 healthy pregnant women. Plasma D-dimer levels were measured during the three trimesters of pregnancy, using a latex-based immunoturbidimetric assay. Reference intervals were calculated according to the Clinical and Laboratory Standards Institute recommendations. D-dimer levels increased progressively and significantly through pregnancy and peaked in the third trimester, in which D-dimer levels were above the conventional cut-off point (500 µg/L) in 99% of pregnant women. The following reference intervals were defined: first trimester: 169–1202 µg/L, second trimester: 393–3258 µg/L and third trimester: 551–3333 µg/L. The study provides reference intervals of D-dimer during the pregnancy using latex-based immunoturbidimetry on the ACL 300 TOP automated coagulation analyser. Further prospective studies of pregnant women with clinical suspicion of VTE are needed to validate these results.

Reference intervals for biochemical, haemostatic and haematological parameters in healthy Chinese women during early and late pregnancy.

Variations in maternal blood parameters, which are mostly induced by the physiological changes that occur during pregnancy, have been reported in different gestational periods. The use of the established reference intervals for healthy adult females leads to the misclassification of healthy pregnant women as abnormal. Our aim was to establish appropriate reference intervals for biochemical, haematological and haemostatic parameters in the first and third trimesters of pregnancy. We included 565 healthy pregnant women with normal pregnancies. Blood samples were collected for biochemical analyses, complete blood counts and coagulation analyses at 8-12 and 28-37 weeks of gestation. The median and reference intervals (the 2.5th and 97.5th values) were calculated for each parameter during pregnancy and then compared to the established reference intervals for healthy adult females. Significant increases in triglyceride, total cholesterol, low-density lipoprotein cholesterol, uric acid, alkaline phosphatase, white blood cell, mean platelet volume, fibrinogen and D-dimer reference intervals and clear decreases in total protein, albumin, blood urea nitrogen, creatinine, red blood cell, haemoglobin, haematocrit, platelet counts and thrombin time reference intervals were observed during pregnancy. According to the 'n%', most changes were observed beginning in the first trimester. Compared to the established reference intervals, the greatest misclassifications were observed for ALB, ALP and D-Di. Changes in maternal blood parameters during pregnancy were confirmed. We recommend that the reference intervals for most blood parameters be revised to account for the gestational period.

Establishing reference intervals for D-dimer to trimesters

Objective: When D-dimer is used to evaluate suspected venous thromboembolism in pregnant patients, the reference interval of common population may cause misinterpretation. The present study aims to determine reference intervals of D-dimer in the three trimesters.Methods: Four-hundred sixteen pregnant women and 32 non-pregnant women were enrolled in this cross-sectional study. Reference group had comprised 123 pregnant in the first trimester (5–11 week), 164 pregnant in the second trimester (13–20 week) and 126 pregnant women in the third trimester (25–35 week). D-dimer levels were analyzed via immunoturbidimetric assay.Results: If the threshold of 0.50 mg/L for diagnosis of VTE is used, 4.8% of pregnant women in the second trimester and 23.8% of pregnant women in the third trimester would have D-dimer levels exceeding this cut-off value. Reference intervals of D-dimer were determined as 0.11–0.40 mg/L; 0.14–0.75 mg/L and 0.16–1.3 mg/L in first, second and third trimester, respectively.Conclusion: The established D-dimer reference intervals for each trimester of pregnancy are different from those used in common population. These reference intervals may assist clinicians in making accurate clinical decisions. Further studies are needed to establish new cut-off values for the D-dimer to rule out VTE in each trimester.

Age- and sex-dependent reference intervals for D-dimer: Evidence for a marked increase by age

A low D-dimer is commonly used to exclude venous thromboembolism in low risk patients. However, the reference intervals are poorly defined and D-dimer has been shown to increase by patient age. We aimed to establish age- and sex-dependent D-dimer reference intervals and to test the consequence of different cut-off limits. By means of the STA-Lia test D-dimer was measured in 1,352 subjects aged between 23 and 93years from the general population. A further 94 subjects were measured with the HemosIL test. The reference intervals were age-dependent with the upper 95% limit increasing from 0.92 FEU mg/L in the age group <50years to 2.39 FEU mg/L in the group ≥70years. Minor differences in the reference intervals between sexes were found. The commonly used cut-off at 0.5 FEU mg/L resulted in a decrease of negatives from 91% in <50years to 56 % in ≥70years. The age-dependent cut-off value (patient's age*0.01 FEU mg/L in 50+ years) resulted in an increase of negatives by age. The linear increase in D-dimer has a slope at approximately 0.0077*age, meaning that a cut-off at (patient's age*0.0077) FEU mg/L, gives an almost constant number of positives across age groups. The two assays showed a poor correlation and a higher percentage of positives using the STA Lia test. The age-dependent increase in D-dimer seen in patients was confirmed, which questions the clinical value of the present cut-off for venous thromboembolism.

Reference intervals of D-dimer during the pregnancy and puerperium period on the STA-R evolution coagulation analyzer

BackgroundPregnant women are at a hyper-coagulable state with a higher risk of deep venous thromboembolism (VTE) and disseminated intravascular coagulation (DIC), which could be life threatening. We established gestational age-specific reference intervals for D-dimer, and estimate the role of D-dimer test in ruling out VTE and DIC in pregnant women. MethodsWe followed 1343 healthy pregnant women and 1042 uncomplicated postpartum women to establish gestational age-specific reference intervals of D-dimer during normal pregnancy. Eighty uncomplicated non-pregnant women were chosen as control group. D-dimer testing was also performed among the patients with pregnancy-related complications. ResultsD-dimer concentration increased progressively during the pregnancy and peaked at the first postpartum day, and then it began to decrease steadily and reach to non-pregnant concentrations on the 42nd postpartum day. The results of several cases that had clinical suspicion of VTE were compared with those of the reference group. ConclusionsThe study provides reference intervals of D-dimer during the pregnancy and postpartum period for women of Chinese Han ethnicity using latex-based immunoturbidimetry on the STA-R evolution coagulation analyzer. Further studies are needed to validate these reference ranges and assess the clinical utility of the reference intervals for D-dimer.

Changes in fibrin D-dimer, fibrinogen, and protein S during pregnancy

Background. Pregnancy is a hypercoagulable state with a 5- to 10- fold higher risk of venous thromboembolism. Existing reference intervals for fibrin D-dimer (D-dimer), functional fibrinogen (fibrinogen) and protein S, free antigen (protein S) are based on non-pregnant patients and reference intervals for pregnant patients are warranted. Objectives. The aim of the present study was to contribute to the establishment of reference intervals for D-dimer, fibrinogen and protein S during pregnancy and to discuss the use of the analyses during pregnancy. Methods. We included 55 healthy pregnant women in gestational week 11–17, with normal current pregnancy. Blood samples were collected in gestational weeks 11–17, 21–27 and 34–37. The three plasma parameters D-dimer, fibrinogen and protein S were analysed by STA-R Evolution®. Results. A significant rise in D-dimer was found from first to second trimester (p < 0.0001) and from second to third trimester (p < 0.0001). The level of fibrinogen rose significantly from second to third trimester (p < 0.0001). Protein S showed a statistically significant fall in the level from first to second trimester (p < 0.0001) and remained stable thereafter. Conclusion. Changes during pregnancy in plasma D-dimer, protein S and fibrinogen were confirmed. Further clinical studies are needed to clarify a clinical useful cut-off point for D-dimer in pregnancy. We suggest careful attention to a low peripartum fibrinogen, since it indicates an increased bleeding risk. We confirmed an earlier suggested lower cut-off point for protein S, during pregnancy.

D‐dimer levels during delivery and the postpartum

D-dimer (DD) measurement has proved to be very useful to exclude venous thromboembolism (VTE) in outpatients. However, during pregnancy, the progressive increase as well as the interindividual variations of DD means that in this instance they are of poor value to rule out VTE. Only a few studies have reported measurements of DD levels in the postpartum. To measure DD sequentially in the puerperium in order to determine when DD levels return to values obtained in non-pregnant women and can again be used in the exclusion of VTE. After uncomplicated pregnancies, 150 women delivering at term either vaginally (n = 100) or by cesarean section (n = 50) were included. DD levels were measured immediately following delivery and next at days 1, 3, 10, 30 and 45. There was a marked elevation of DD at delivery, especially when instrumental. All DD measurements were above 500 ng mL(-1) at delivery, at day 1 and at day 3 postpartum. A sharp decrease in DD was observed between day 1 and day 3, followed by a slight increase at day 10. At day 30 and day 45, respectively, 79% and 93% of women in the vaginal delivery group and 70% and 83% in the cesarean group had levels below 500 ng mL(-1). Bleeding, breastfeeding and heparin prophylaxis did not modify DD levels significantly. Using the Vidas DD new assay, our study provides reference intervals for DD in the postpartum period. Using a cut-off at 500 ng mL(-1), DD measurement for ruling out VTE was found to be useful again 4 weeks after delivery.