The role of lung scintigraphy in the diagnosis of nephrotic syndrome with pulmonary embolism

Purpose: Patients with nephrotic syndrome (NS) have an increased tendency t o develop thrombosis and even to progress to pulmonary embolism (PE). This study was performed to determine the incidence of PE in NS with severe hypo albuminemia and to investigate the possible role of ventilation-perfusion ( V/Q) lung scans to evaluate these patients. Methods: Eighty-nine patients with NS(serum albumin concentration < 2 g/dl) and risk factors for PE were studied. In all patients, the probability tha t PE would develop was assessed based on the results of V/Q lung scans (Xe- 133 for ventilation and Tc-99m MAA for perfusion imaging). The lung scans w ere judged using the modified Prospective Investigation of Pulmonary Emboli sm Diagnosis criteria. In 25 (28%) patients whose lung scans showed an inte rmediate or low probability, but for whom there was a strong clinical indic ation of PE, pulmonary angiography was performed. The patients' clinical sy mptoms and signs on initial examination were observed. Additional examinati ons included electrocardiograms, chest radiography, and hematochemical test s such as albumin, blood urea nitrogen, creatinine, cholesterol, triglyceri des, fibrinogen, antithrombin III, prothrombin time, and activated partial thromboplastin time. Results: Based on the findings of lung scans, 19 (21%) of the patients were categorized as having a high probability of PE. However, pulmonary angiogr aphy found that 10 (11%) other patients had PE despite having lung scan fin dings categorized as intermediate or low probability of PE. Except for plas ma fibrinogen and antithrombin III levels, neither the clinical symptoms an d signs, electrocardiogram findings, chest radiograph results, nor values o f hematochemical testing were consistent with the occurrence of PE in these 29 patients. Conclusion: The results of this study suggest that PE is not a rare complic ation in patients with NS, and is usually clinically silent. In this series , the occurrence of PE did not appear to be always correlated with the clin ical or hematochemical severity of NS, except for the association with elev ated levels of fibrinogen and antithrombin ill. When treating the clinical symptoms of patients with NS, physicians should be alert to the possible co mplication of PE. Serial V/Q lung scans may provide valuable clues in the e valuation of these patients.