Proteinuria in metastatic pheochromocytoma is associated with an increased risk of Acute Respiratory Distress Syndrome, spontaneously or after therapy with 131I-meta-iodobenzylguanidine (131I-MIBG).

Acute Respiratory Distress Syndrome (ARDS) has been reported rarely in pheochromocytoma, occurring spontaneously or after therapy with 131I-meta-iodobenzylguanidine (131I-MIBG). Our objective was to determine whether proteinuria is associated with an increased risk of ARDS. This was a retrospective analysis of a prospective cohort study of 64 patients with metastatic pheochromocytoma or paraganglioma treated with 131I-MIBG on institutional protocols. Proteinuria was defined as at least one urinalysis positive for at least trace protein within 1 month prior to 131I-MIBG or within 1 month prior to spontaneous ARDS. Proportions were compared using Fisher's exact test. Urinalyses within the defined time period were available for 48 patients, 8 of whom had proteinuria. Of the 8 patients with proteinuria, 5 developed ARDS: 3 within 10 days following 131I-MIBG, two 6 months following 131I-MIBG. Both patients who developed ARDS 6 months after 131I-MIBG had proteinuria within 1 month before apparently spontaneous ARDS. None of the 40 patients whose urinalyses were all negative for protein developed ARDS. None of the 16 patients with missing urinalyses developed ARDS. Patients with antecedent proteinuria were more likely to develop ARDS than those without proteinuria (63% vs. 0%; p<0.0001). The following variables were not significantly associated with ARDS: 131I-MIBG activities administered, number of 131I-MIBG administrations, age, hypertension, or secretion of catecholamines or metanephrines. In patients with metastatic pheochromocytoma or paraganglioma, proteinuria is associated with ARDS and urine protein should be examined prior to administering 131I-MIBG.