Hematoloji Testlerinde Preanalitik Evre Sempozyumu, İstanbul, Turkey, 15 March 2019, vol.2, pp.96
D-dimer is a fibrin degradation end product generated during fibrinolysis. D-dimer assays are commonly used in clinical practice to exclude diagnosis of deep vein thrombosis or pulmonary embolism. Besides, its increase is shown in cases with inflammation, cancer and after surgery. We tried to evaluate the reasons for the elevation of D-dimer in our case.
Male patient, 74 years old admitted to our Pulmonary Diseases Outpatient Clinics with dyspnea. Thorax CT showed pleural effusion and pneumonia was the diagnosis. Also D-dimer analysis revealed a high result which was 8490ug/L (reference range <654 ug/L). With a clinically medium high probability of pulmonary embolism his therapy was planned. Consecutive D-dimer requests revealed high results despite his dyspnea recovered with therapy and the last D-dimer result was 2980 ug/L. Due to lack of clinical and radiological finding to support the diagnosis of pulmonary embolism other than elevation of D-dimer pulmonologists requested a consultation from our laboratory. After assessment of the patients test results, plasma was treated with heterophilic blocking tube (HBT) to rule out the heterophilic antibodies. Upon treatment D-dimer analysis was repeated using same immunoassay method and the results before and after HBT use were 2390 ug/L and 1850 ug/L, consecutively. Then D-dimer analysis was repeated on another device using a different method (immune-turbidimetric method) however similar results were obtained (1175 ug/L and 1142 ug/L; reference range <500 ug/L). Rheumatoid factor was also analyzed to rule out its interference with D-dimer assays and again it was found in the reference range (3.94 kIU/L; reference range <14 kIU/L). Patient’s creatinine values were over the reference range (3.83.mg/dl) which was the only probable reason for D-dimer elevation in this patient was chronic renal impairment (CRI).
D-dimer can be interfered from different pre analytical factors. Patient’s age, presence of heterophilic antibodies, osteoarthritis, knee or hip joint replacement operations, renal impairments are the known factors that should be evaluated for D-dimer interferences. We suggest new D-dimer reference range studies should be done on CRI patients since it is hazardous to use contrast agent in pulmonary embolism for diagnosis.