Pulmonary embolism laboratory findings
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Editor(s)-In-Chief: C. Michael Gibson, M.S., M.D. [1], The APEX Trial Investigators; Associate Editor(s)-in-Chief:
Overview
The results of routine laboratory tests including arterial blood gas analysis are non-specific in making the diagnosis of pulmonary embolism. These laboratory studies can be obtained to rule-out other cause of chest discomfort and tachypnea. In patients with acute pulmonary embolism, non-specific lab findings include: leukocytosis, elevated ESR with an elevated serum LDH and serum transaminase (especially AST or SGOT). A negative D-dimer in a patient with low to intermediate probability of pulmonary embolism strongly suggests pulmonary embolism is not present.
Laboratory Findings
D-dimer Test
- The D-dimer cut-off values varies among tests; however, plasma D-dimer > 500 ng/mL is the most commonly used cut-off concentration.[1]
- Plasma D-dimer>500 ng/ml, PE present (97% sensitive and 45% specific)
- Plasma D-dimer<500 excludes PE (Have a high negative predictive value)
- However, the use of the cut off value 500 ng/mL for abnormal D-dimer limits the diagnostic role of D-dimer in the elderly, among whom D-dimer increases with age in the absence of any ongoing venous thromboembolism process. In a metanalysis of 5 cohort studies of 2818 subjects with low clinical probability of DVT, the use of an age adjusted cut-off value of D-dimer increases the number of subjects in whom DVT can be excluded.[2] A metaanalysis of 13 cohorts of 12,497 patients with a low probability of venous thromboembolism revealed that the use of an age adjusted cut point for the D-dimer concentration increases the specificity of this test without altering its sensitivity.[3]
- According to a multicenter, multinational prospective study of 3346 subjects presenting to the emergency department for suspicion of pulmonary embolism, the use of a fixed D-dimer cut-off value is compared to an age adjusted D-dimer cut-off value. The use of the age adjusted cut-off value in patients with low clinical probability of pulmonary embolism is associated with an increased number of patients in whom pulmonary embolism is excluded with a decreased likelihood of the occurrence of subsequent venous thromboembolism episodes.[4]
- The age adjusted cut off value of D-dimer is the following:
Routine Blood Tests
- Pulmonary embolism arterial blood gas analysis
- In patients with acute pulmonary embolism, routine laboratory findings are non-specific and include:
- Leukocytosis
- Elevated ESR with an elevated serum LDH and serum transaminase (especially AST or SGOT)
- Serum bilirubin levels are found to be within normal limits
Workup for Hypercoagulability
- Workup for hypercoagulation: which include
- Activated protein C resistance
- Factor V Leiden mutation
- Protein C
- protein S, free and total.
- Antithrombin
- Lupus anticoagulant
- Anticardiolipin antibodies
- Plasma homocysteine values
References
- ↑ Stein PD, Hull RD, Patel KC, Olson RE, Ghali WA, Brant R, Biel RK, Bharadia V, Kalra NK (2004). "D-dimer for the exclusion of acute venous thrombosis and pulmonary embolism: a systematic review". Annals of Internal Medicine. 140 (8): 589–602. PMID 15096330. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ 2.0 2.1 Douma RA, Tan M, Schutgens RE, Bates SM, Perrier A, Legnani C; et al. (2012). "Using an age-dependent D-dimer cut-off value increases the number of older patients in whom deep vein thrombosis can be safely excluded". Haematologica. 97 (10): 1507–13. doi:10.3324/haematol.2011.060657. PMC 3487551. PMID 22511491.
- ↑ 3.0 3.1 Schouten HJ, Geersing GJ, Koek HL, Zuithoff NP, Janssen KJ, Douma RA; et al. (2013). "Diagnostic accuracy of conventional or age adjusted D-dimer cut-off values in older patients with suspected venous thromboembolism: systematic review and meta-analysis". BMJ. 346: f2492. doi:10.1136/bmj.f2492. PMC 3643284. PMID 23645857.
- ↑ 4.0 4.1 Righini M, Van Es J, Den Exter PL, et al. Age-Adjusted D-Dimer Cutoff Levels to Rule Out Pulmonary Embolism: The ADJUST-PE Study. JAMA. 2014;311(11):1117-1124. doi:10.1001/jama.2014.2135.