CLINICAL RESEARCH STUDY D-dimer Testing in Patients with Suspected Pulmonary Embolism and Impaired Renal Function Reza Karami-Djurabi, MD, Frederikus A. Klok, MD, Judith Kooiman, Sophie I. Velthuis, Mathilde Nijkeuter, MD, PhD, Menno V. Huisman, MD, PhD Section of Vascular Medicine, Department of General Internal Medicine – Endocrinology, Leiden University Medical Center, Leiden, the Netherlands. ABSTRACT BACKGROUND: Determination of pretest probability and D-dimer tests are the first diagnostic steps in patients with suspected pulmonary embolism, which can be ruled out when clinical probability is unlikely and D-dimer level is normal. We evaluated the utility of D-dimer testing in patients with impaired renal function. METHODS: D-dimer tests were performed in consecutive patients with suspected pulmonary embolism and an unlikely clinical probability. Creatinine levels were assessed as clinical routine. Glomerular filtration rate was calculated using the Modification of Diet in Renal Disease formula. Correlation between D-dimer level and renal function and proportions of patients with normal D-dimer in different categories of estimated glomerular filtration rate (eGFR) were assessed. Different categories of decreasing eGFR were defined as: normal renal function (eGFR 89 mL/min), mild decrease in eGFR (eGFR 60-89 mL/min), and moderate decrease in eGFR (eGFR 30-59 mL/min). RESULTS: Creatinine levels were assessed in 351 of 385 patients (91%). D-dimer levels significantly increased in 3 categories of decreasing eGFR (P = .027 and P = .021 for moderate renal impairment compared with mild renal impairment and normal renal function, respectively). Normal D-dimer levels were found in 58% of patients with eGFR 89 mL/min, in 54% with eGFR 60-89 mL/min, and in 28% with eGFR 30-59 mL/min. CONCLUSIONS: The specificity of D-dimer testing in patients with suspected pulmonary embolism and decreased GFR is significantly decreased. Nonetheless, performing D-dimer tests is still useful because computed tomography scanning can be withheld in a significant proportion of these patients. © 2009 Elsevier Inc. All rights reserved. • The American Journal of Medicine (2009) 122, 1050-1053 KEYWORDS: Creatinine; D-dimer; Glomerular filtration rate; Pulmonary embolism; Renal function The diagnostic workup of patients with clinically suspected acute pulmonary embolism has been greatly simplified. Two simple bedside tests can safely exclude pulmonary embo- lism from the differential diagnosis in 20%-40% of the patients, without the need for diagnostic radiological imaging, reducing costs, time, and exposure to radiation and contrast dye. 1,2 These tests include the determination of the patients’ pretest probability for pulmonary embo- lism by means of a clinical prediction rule and a blood test measuring D-dimer concentration. 1-4 Pulmonary em- bolism can be ruled out in patients with an unlikely clinical probability (pretest probability less than approx- imately 15%-20%) in combination with a normal D- dimer test result and radiological imaging, and anticoag- ulant treatment can safely be withheld. 1-4 In patients with either an abnormal D-dimer test result or a likely clinical probability, the diagnosis should be established or ex- cluded by computed tomography (CT) or ventilation/ perfusion lung scanning. 1,2 D-dimer levels can be elevated in all clinical conditions that are associated with enhanced fibrin formation, includ- Funding: This study was supported in part by unrestricted grants from our hospital. Conflict of Interest: None. Authorship: All authors had access to the data and a role in drafting and writing the manuscript. Requests for reprints should be addressed to Menno V. Huisman, MD, PhD, LUMC (C4-70), Albinusdreef 2, Postbus 9600, 2300 RC Leiden, The Netherlands. E-mail address: M.V.Huisman@LUMC.nl 0002-9343/$ -see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.amjmed.2009.03.032