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Methodology and Clinical Implementation of Ventilation/Perfusion Tomography for Diagnosis and Follow-up of Pulmonary Embolism and Other Pulmonary Diseases
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Before performing imaging tests, it is recommended to estimate the clinical probability for PE [7]. Usually, a Wells score is applied. The measurement of D-dimer – a breakdown product of cross-linked fibrin clot – is widely used in the investigative workup of patients with suspected venous thromboembolism. However, D-dimer has a low specificity (40%) because a number of conditions, other than venous thromboembolism, may cause it to be elevated: For example, acute myocardial infarction, stroke, inflammation, active cancer, and pregnancy. The specificity declines even further with age and, in the elderly, may reach only 10 per cent [8]. Due to the low predictive value, a positive quantitative D-dimer test does not modify the pre-test probability. A negative quantitative D-dimer test combined with a low clinical probability is associated with a low risk of thromboembolic disease. At moderate to high pre-test clinical probability, D-dimer has no incremental value.
Cardiovascular system
Published in David A Lisle, Imaging for Students, 2012
D-dimer is a plasma constituent present when fibrin is released from active thrombus. Various assays for d-dimer are available. Of these, the quantitative enzyme-linked immunosorbent assay (ELISA) has a sensitivity of over 95 per cent, though is highly non-specific. It therefore has a very high negative predictive value. The diagnosis of PE is reliably excluded if the clinical pretest probability is low and the d-dimer assay is negative. In such patients, imaging with CTPA or scintigraphy is not indicated. Imaging is indicated where the clinical pretest probability is moderate or high or where the d-dimer assay is positive.
Clinical Applications of Immunoassays
Published in Richard O’Kennedy, Caroline Murphy, Immunoassays, 2017
A D-dimer level >500 ng mL−1 is taken to be significant; however, it is important that the patient’s risks factors for thrombus formation, i.e. the pretest probability, are determined prior to interpretation of D-dimer values. While multiple assays are used in the measurement of D-Dimer levels, the evidence indicates that a D-dimer level <500 ng mL−1 by quantitative ELISA or semi-quantitative latex agglutination can exclude a PE in patients with a low to moderate risk of PE [42].
Hydroxychloroquine improves high-fat-diet-induced obesity and organ dysfunction via modulation of lipid level, oxidative stress, and inflammation
Published in Egyptian Journal of Basic and Applied Sciences, 2023
Mohamed A Hasan, Omar A. Ammar, Maher A Amer, Azza I Othman, Fawzia Zigheber, Mohamed A El-Missiry
Serum lipid fraction levels, including total lipids, total cholesterol (TC), triglycerides (TG), and high-density lipoprotein (HDL), were assessed using colorimetric test kits purchased from Spinreact (Girona, Spain). Friedewald’s formula was used to calculate the level of low-density lipoprotein cholesterol (LDL-C) and very low-density lipoprotein cholesterol (VLDL-C) [19]. Creatine kinase myocardial band (CK-MB) and lactic dehydrogenase (LDH) activities in the serum were estimated in accordance with the standard methods using kits purchased from BioSystems (Barcelona, Spain). Serum troponin T level was determined using the sandwich enzyme immunoassay technique kit purchased from Kamiya Biomedical (Seattle, USA). Lipid peroxidation was determined by estimating the amount of 4-hydroxynonenal (4-HNE) according to the manufacturer’s instructions (FineTest, Wuhan, China). Glutathione (GSH) concentration and glutathione peroxidase (GPx) activities were estimated using kits supplied by Biodiagnostic (Giza, Egypt). Serum IL-6, IL-10, and TNF-α levels were assessed using ELISA kits purchased from BosterBio (California, USA) and ElisaGenie (London, UK). Leptin and adiponectin were measured in serum using an ELISA mouse leptin immunoassay kit (Catalog No: MOB00) and ELISA mouse Adiponectin/Acrp30 immunoassay kit (Catalog No: MRP300) obtained from R & D systems, MN, USA. Plasma D-dimer was determined using the Innovance D-dimer assay (Siemens, Marburg, Germany).
Blood biochemical parameters for assessment of COVID-19 in diabetic and non-diabetic subjects: a cross-sectional study
Published in International Journal of Environmental Health Research, 2022
Syeda Umme Fahmida Malik, Parveen Afroz Chowdhury, Al Hakim, Mohammad Shahidul Islam, Md Jahangir Alam, Abul Kalam Azad
D-dimer is released through the cleavage of fibrin by plasmin to degrade clots formed in venous thromboembolism (VTE). It is an indirect marker of active coagulation and thrombin formation during endovascular thrombotic processes (Linkins and Takach Lapner 2017). Therefore, elevations in D-dimer levels in COVID-19 patients might be helpful to rapidly identify those that have high disease severity, pulmonary complications, and risk of VTE (Paliogiannis et al. 2020). In the present study, it was found that the levels of D-dimer were positively correlated with the COVID-19 patients (Table 2). The D-dimer elevations (≥0.5 µg/mL) were seen in ~50% of the suspected COVID-19 patients. The hospitalized patients having normal D-dimer (<0.5 µg/mL) were not confirmed with COVID-19 positive, suggesting that increased D-dimer would create a suitable environment for attacking by SARS-CoV-2. The D-dimer levels observed among the COVID-19 positive patients in our study (Table 2) are similar to those reported by other studies (Chen et al. 2020; Huang et al. 2020; Zhou et al. 2020a). The D-dimer appears significantly higher in severe COVID-19 patients compared to non-severe ones, and the level >1 µg/mL is supposed as one of the risk factors for mortality in adult patients with COVID-19 (Zhang et al. 2020). It has been reported that about 50% of the COVID-19 patients with poor prognosis had increased D-dimer levels (Guan et al. 2020; Tang et al. 2020). In the present study, the elevated level of D-dimer was observed in 70 (71.43%) of COVID-19 patients [males 41 (58.57%), females 29 (41.43%)]. However, only 9 patients died. Although D-dimer is supposed associated with a poor outcome (Chen et al. 2020; Huang et al. 2020; Zhou et al. 2020a), the cause of elevated D-dimer level is multifactorial and its cutoff value is not yet established for COVID-19 patients. Therefore, the elevated level of D-dimer observed in large numbers of COVID-19 patients (71.43%) in the present study indicate that D-dimer test might be useful for COVID-19 assessment and understand the requirement of hospitalization rather than severity of clinical presentation (Thachil et al. 2020).