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.