Interpretations

An elevation of D-dimer (>500 ng/mL) indicates activation of coagulation with formation and degradation of cross-linked fibrin. It is a very sensitive, albeit very nonspecific, marker of pulmonary embolism (PE) or deep venous thrombosis (DVT). The main value of D-dimer testing in the setting of possible PE or DVT is its negative rule-out capability. A negative D-dimer result, when the pre-test probability of PE or DVT is low to intermediate, essentially excludes PE and DVT. In healthy adults D-dimer levels increase in a linear fashion after age 50. Based on current literature**, by optimizing the cutoffs with age, the very high sensitivity of the test can be maintained while providing greater specificity. This allows a greater percentage of older adults to be ruled-out. This allows a simple calculation of AGE x 10 for patients over 50 years old. For example, a 65 year-old patient would now have a cutoff of < 650 ng/mL (i.e. values of 650 ng/mL or less considered negative).

**Righini M, Van Es J, Exter D, et al. Age-Adjusted D-Dimer Cutoff Levels to Rule Out Pulmonary Embolism The ADJUST-PE Study. JAMA. 2014;311:1117.

**Raja AS, Greenberg JO, Qaseem A. Evaluation of Patients With Suspected Acute Pulmonary Embolism: Best Practice Advice From the Clinical Guidelines Committee of the American College of Physicians. Ann Intern Med. 2015;163:701.