Editing D-dimer (section)

===Thrombotic disease===
Various kits have a 93 to 95% [[Sensitivity and specificity#Sensitivity|sensitivity]] (true positive rate). For hospitalized patients, one study found the [[Sensitivity and specificity#Specificity|specificity]] to be about 50% (related to false positive rate) in the diagnosis of thrombotic disease.<ref>{{cite journal | vauthors = Schrecengost JE, LeGallo RD, Boyd JC, Moons KG, Gonias SL, Rose CE, Bruns DE | title = Comparison of diagnostic accuracies in outpatients and hospitalized patients of D-dimer testing for the evaluation of suspected pulmonary embolism | journal = Clinical Chemistry | volume = 49 | issue = 9 | pages = 1483–90 | date = September 2003 | pmid = 12928229 | doi = 10.1373/49.9.1483 | doi-access = free }}</ref>
* [[False positive]] readings can be due to various causes: [[liver]] disease, high [[rheumatoid factor]], [[inflammation]], [[cancer|malignancy]], [[Physical trauma|trauma]], [[pregnancy]], recent [[surgery]] as well as advanced age.<ref>{{cite journal | vauthors = Kabrhel C, Mark Courtney D, Camargo CA, Plewa MC, Nordenholz KE, Moore CL, Richman PB, Smithline HA, Beam DM, Kline JA | display-authors = 6 | title = Factors associated with positive D-dimer results in patients evaluated for pulmonary embolism | journal = Academic Emergency Medicine | volume = 17 | issue = 6 | pages = 589–97 | date = June 2010 | pmid = 20624138 | pmc = 3538031 | doi = 10.1111/j.1553-2712.2010.00765.x }}</ref>
* [[False negative]] readings can occur if the sample is taken either too early after thrombus formation or if testing is delayed for several days. Additionally, the presence of anti-coagulation can render the test negative because it prevents thrombus extension. The anti-coagulation medications [[dabigatran]] and [[rivaroxaban]] decrease D-dimer levels but do not interfere with the D-dimer assay.<ref name="BaglinKeeling2012">{{cite journal | vauthors = Baglin T, Keeling D, Kitchen S | title = Effects on routine coagulation screens and assessment of anticoagulant intensity in patients taking oral dabigatran or rivaroxaban: guidance from the British Committee for Standards in Haematology | journal = British Journal of Haematology | volume = 159 | issue = 4 | pages = 427–9 | date = November 2012 | pmid = 22970737 | doi = 10.1111/bjh.12052 | doi-access = free }}</ref>
* False values may be obtained if the specimen collection tube is not sufficiently filled (false low value if underfilled and false high value if overfilled). This is due to the dilutional effect of the anticoagulant (the blood must be collected in a 9:1 blood to anticoagulant ratio).
* Likelihood ratios are derived from sensitivity and specificity to adjust pretest probability.

In interpretation of the D-dimer, for patients over age 50, a value of (patient's age) × 10 μg/L may be abnormal.<ref name="pmid22072293">{{cite journal | vauthors = van Es J, Mos I, Douma R, Erkens P, Durian M, Nizet T, van Houten A, Hofstee H, ten Cate H, Ullmann E, Büller H, Huisman M, Kamphuisen PW | display-authors = 6 | title = The combination of four different clinical decision rules and an age-adjusted D-dimer cut-off increases the number of patients in whom acute pulmonary embolism can safely be excluded | journal = Thrombosis and Haemostasis | volume = 107 | issue = 1 | pages = 167–71 | date = January 2012 | pmid = 22072293 | doi = 10.1160/TH11-08-0587 | s2cid = 4832019 }}</ref><ref name="pmid20354012">{{cite journal | vauthors = Douma RA, le Gal G, Söhne M, Righini M, Kamphuisen PW, Perrier A, Kruip MJ, Bounameaux H, Büller HR, Roy PM | display-authors = 6 | title = Potential of an age adjusted D-dimer cut-off value to improve the exclusion of pulmonary embolism in older patients: a retrospective analysis of three large cohorts | journal = BMJ | volume = 340 | pages = c1475 | date = March 2010 | pmid = 20354012 | pmc = 2847688 | doi = 10.1136/bmj.c1475 }}</ref>