D-dimer test: Definition, diagnosis, and what to expect Health ConditionsHealth ConditionsAlzheimer's & DementiaAnxietyArthritisAsthma & AllergiesBreast CancerCancerCardiovascular HealthCOVID-19Dermatology & SkincareDiabetesEnvironment & SustainabilityExercise & FitnessEye HealthHeadache & MigraineHealth EquityHIV & AIDSHuman BiologyInflammatory Bowel DiseaseLeukemiaLGBTQIA+Men's HealthMental HealthMultiple Sclerosis (MS)NutritionParkinson's DiseasePsoriasisSexual HealthWomen's HealthDiscoverNewsLatest NewsOriginal SeriesMedical MythsHonest NutritionThrough My EyesNew Normal HealthPodcastsHow to understand chronic painWhat is behind vaccine hesitancy?The amazing story of hepatitis C, from discovery to cureNew directions in dementia researchCan psychedelics rewire a depressed, anxious brain?Why climate change matters for human healthToolsGeneral HealthDrugs A-ZHealth HubsHealth ToolsBMI Calculators and ChartsBlood Pressure Chart: Ranges and GuideBreast Cancer: Self-Examination GuideSleep CalculatorHealth ProductsAffordable Therapy OptionsBlood Pressure MonitorsDiabetic SuppliesFitness TrackersHome GymsGreen Cleaning ProductsHow to Shop for CBDQuizzesRA Myths vs FactsType 2 Diabetes: Managing Blood SugarAnkylosing Spondylitis Pain: Fact or FictionConnectAbout Medical News TodayWho We AreOur Editorial ProcessContent IntegrityConscious LanguageNewslettersSign UpFollow UsMedical News TodayHealth ConditionsDiscoverToolsConnectSubscribe What is a D-dimer test Medically reviewed by Angelica Balingit, MD — By Mathieu Rees on June 6, 2022A D-dimer test checks for a small protein fragment that can help identify blood clotting problems. A positive result may suggest a recent blood clot formation and breakdown in the body, which could indicate a blood clotting condition. The blood’s clotting function is an important process that can help prevent a person from losing too much blood after an injury to a blood vessel. The body forms a blood clot when several proteins join together at the site of injury. Once the site heals, the body produces another protein to break the clot into small pieces. One of these protein fragments is known as a D-dimer. D-dimer is not usually detectable in blood and is usually only present after the breakdown of a blood clot. Therefore, a doctor can use a D-dimer test to identify an increase in the body’s clotting mechanisms, which could help identify a coagulation disorder. In this article, we will discuss what a D-dimer test is, what it can help detect, what to expect from the test, and how to interpret its results. Definition Share on PinterestJohner Images/Getty ImagesA D-dimer test is a blood test that measures the level of D-dimer, a protein fragment that is present in blood after the breakdown of a blood clot. When blood clots break down, it produces fibrin degradation products (FDPs). One of these FDPs is known as D-dimer, which consists of variously sized pieces of crosslinked fibrin. This test can be useful for indicating the presence of elevated clotting mechanisms and can assist a doctor in reaching a diagnosis. However, D-dimer tests are very sensitive and can result in false positives and negatives. As such, this means that further tests are necessary to accurately diagnose blood clotting disorders. What conditions can it diagnose D-dimer tests could help doctors detect a variety of blood clotting disorders, which can include:Pulmonary embolism (PE): Refers to a blockage in the pulmonary artery, which supplies the blood to the lungs. An embolism describes when a blood clot travels to the blood vessels of the lungs and becomes stuck. As this can cause problems with blood flow and gas exchange, it can become a life threatening event.Deep vein thrombosis (DVT): Occurs when a blood clot, or thrombus, forms in a deep vein within the body. DVT can have serious consequences, as the blood clot can damage the valves in a vein. The clot may also break free and potentially result in a pulmonary embolism.Disseminated intravascular coagulation: Describes a widespread hypercoagulable state, which may prevent blood from clotting normally. This can compromise blood flow and can result in multiple organ dysfunction. Who may require the test A doctor may request a D-dimer test when they suspect a person may have a blood clotting problem. They may particularly recommend a test if an individual presents with DVT or PE symptoms, such as pain and swelling in the affected limb or labored breathing and chest pain. Additionally, as it is a quick and noninvasive test, they may also use it to help rule these conditions out. A healthcare professional may also order this test along with other blood tests to help reach a diagnosis. If a person is undergoing treatment for DIC, a doctor may use a D-dimer test to help monitor a person’s condition. What to expect To perform a D-dimer test, a doctor will require a blood sample. They will typically draw the blood sample through a needle from a vein in the arm. As with any test that involves needles, it may carry a small risk of bleeding, infection, or bruising. An individual may feel a slight stinging or painful sensation at the site where they collect the sample. They do not need to prepare anything prior to the test. After collecting the sample, the doctor or nurse will send it to a laboratory. Lab workers will then test the blood sample for the presence of D-dimers, before returning the results to the doctor. The doctor then organizes an appointment with the individual, where they may discuss the results and any further steps. Interpreting results A 2021 paper notes that a typical D-dimer blood level is less than 0.50. As such, a doctor will consider a score of 0.50 or higher as a positive result. A positive result indicates atypically high levels of proteins that relate to blood clot formation and breakdown, which could suggest a blood clotting condition. A typical result likely means a person does not have an acute blood clot or condition causing atypical clot formation and breakdown. While D-dimer tests are very sensitive, meaning they often pick up existing blood clotting problems, they are not very specific, which means they may provide a positive result when no disease is present. A wide variety of factors can cause elevated D-dimer levels, including:pregnancycigarette smokingphysical traumacancerinfectionssepsisbeing olderbeing immobilehaving an autoimmune disease Many healthcare professionals may consider D-dimer as an additional test. When a doctor discerns that an individual has elevated D-dimer levels, they will request further testing to reach an accurate diagnosis. How clotting works and risk factors Blood clotting is a vital process that can prevent excessive bleeding. When there is damage to a blood vessel, it gets smaller to let less blood through. Next, platelets immediately adhere to the injury and release chemicals that attract even more platelets, forming a platelet plug. Finally, clotting factor proteins work together to form threads of a protein known as fibrin. The fibrin threads then weave over the platelet plug to create a strong clot, which allows the body to heal the injured blood vessels. As part of the healing process, the body then begins to break down the fibrin clot, which releases proteins such as D-dimer. Factors that can increase the risk of developing a blood clot can include:obesitypregnancybeing immobilesmokingoral contraceptivescertain cancerstraumacertain surgeriesolder agefamily history of blood clotschronic inflammatory diseasesdiabeteshypertensionhigh cholesterol Summary D-dimer is a blood test that can detect proteins present after the formation and breakdown of a blood clot. It can help doctors diagnose coagulation conditions that may affect blood clotting. While the test is quick, noninvasive, and sensitive, it is also not very specific. This means that while it can be a useful test in the diagnostic process, a doctor will request other tests to help them reach an accurate diagnosis. Last medically reviewed on June 6, 2022Blood / HematologyMedical Devices / Diagnostics 12 sourcescollapsedMedical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.Blood clots. (n.d.). https://www.hematology.org/education/patients/blood-clotsBounds, E. J., et al. (2021). D dimer. https://www.ncbi.nlm.nih.gov/books/NBK431064/Costello, R. A., et al. (2021). Disseminated intravascular coagulation. https://www.ncbi.nlm.nih.gov/books/NBK441834/D-dimer. (2020). https://labtestsonline.org.uk/tests/d-dimerD-dimer. (2021). https://pathologytestsexplained.org.au/learning/test-index/d-dimerD-dimer. (n.d.). https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=d_dimerD-dimer test. (2020). https://www.healthdirect.gov.au/d-dimer-testD dimer test. (2021). https://medlineplus.gov/lab-tests/d-dimer-test/Linkins, L.-A., et al. (2017). Review of D-dimer testing: Good, bad, and ugly. https://onlinelibrary.wiley.com/doi/full/10.1111/ijlh.12665Rali, P., et al. (n.d.). Pulmonary embolism [Fact sheet]. https://www.thoracic.org/patients/patient-resources/resources/pulmonary-embolism.pdfUnderstanding how blood works. (n.d.). https://www.hog.org/handbook/section/1/understanding-how-blood-worksWaheed, S. M., et al. (2021). Deep vein thrombosis.https://www.ncbi.nlm.nih.gov/books/NBK507708/FEEDBACK:Medically reviewed by Angelica Balingit, MD — By Mathieu Rees on June 6, 2022 Latest newsWhat sets 'SuperAgers' apart? 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