A fatal case of propylthiouracil-induced ANCA-associated vasculitis resulting in rapidly progressive glomerulonephritis, acute hepatic failure, and cerebral angiitis.

INTRODUCTION: Propylthiouracil (PTU)-induced antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis presenting with renal failure, acute hepatic failure, and cerebral angiitis is a rare yet fatal disease. Early diagnosis and management may help in reducing mortality and morbidity. Plasmapheresis and induction with either cyclophosphamide or rituximab is indicated. Understanding the pathophysiology and complex management of this disease poses challenges to clinicians. CASE REPORT: A 42-year-old woman presented with acute renal and hepatic failure. She had been on PTU for 11 months for Graves' disease. Initial urine microscopy showed red blood cell casts. Anti PR-3 antibodies were positive. Kidney biopsy revealed pauci-immune glomerulonephritis with crescent formation. Renal and hepatic failures were attributed to PTU-induced c-ANCA production as other serological workup was negative. Pulse steroids and plasmapheresis were initiated. Later she developed pneumonia. She was also given rituximab. After the first dose of rituximab, plasmapheresis was held for 3 days. The second dose of rituximab was given in 5 days owing to removal by plasmapheresis. She got 8 sessions of plasmapheresis. She also developed seizures and MRA of her head revealed cerebral infarct, with findings suggestive of cerebral angiitis. She did not recover and expired 20 days after presentation. CONCLUSION: PTU can cause ANCAassociated vasculitis resulting in multiorgan failure. Plasmapheresis should be held for 3 days after rituximab infusion in order to allow maximum exposure. The second dose of rituximab may be given before the recommended 7-day interval in cases in which plasmapheresis is being performed to maximize therapeutic benefit.

Spurious hyperphosphatemia related to severe hyperbilirubinemia in patients with end-stage liver disease.

AIM: Accurate assessment and management of hyperphosphatemia is a key component of the care of patients with both acute and chronic kidney disease (CKD). In some cases, hyperphosphatemia may be spurious, and failure to recognize this may lead to complications. We report 6 cases of spurious hyperphosphatemia in patients with end-stage liver disease (ESLD) that was associated with severe hyperbilirubinemia. METHODS: Six patients with ESLD and severe hyperbilirubinemia were found to have high serum phosphorus (PO4) using our Beckman Coulter Synchron LX20 or DxC analyzers. Samples were sent to an affiliated hospital that uses the Roche Integra analyzer, for evaluation to rule out spurious elevations of serum phosphorus. We also measured serum levels of parathyroid hormone (PTH), calcium, creatinine, total protein, and total bilirubin. Data were analyzed by t-test. RESULTS: Mean serum PO4 using the Beckman analyzers was 7.5 mg/dL (SD ± 1.98); using the Roche Integra analyzer it was 4.0 mg/dL (SD ± 0.44) (mean difference = 3.5 mg/dL; p = 0.0017). Mean PTH and calcium levels were 43 pg/mL and 9.1 mg/dL, respectively. Mean total bilirubin level was 27.9 mg/dL and mean total protein was 6.0 g/dL. CONCLUSION: The Beckman LX20 and DxC analyzers use time-dependent photometric methods to measure serum PO4 which can be affected by hyperbilirubinemia. In contrast, the Roche Integra analyzer uses an endpoint photometric method with sample blanking, which helps to correct for the effect of hyperbilirubinemia. Clinicians managing patients with marked hyperbilirubinemia should consider spurious laboratory abnormalities.