Case Presentation: A 72-year-old male presented to the emergency room for macrocytic anemia and a creatinine of 9.72 mg/dL on outpatient lab work. Past medical history was notable for paroxysmal supraventricular tachycardia, gastroesophageal reflux disease and heart failure with reduced ejection fraction. On admission, he complained of six months of fatigue with constipation, 60 lbs of weight loss and black stools. His outpatient workup in the three months prior included unremarkable colonoscopy and CT abdomen/pelvis. His labs in the emergency room were notable for creatinine of 11.50 mg/dL, hemoglobin of 8.1 g/dL, and mean corpuscular volume of 100 fl. Two days after admission, he continued to have black stools, and his hemoglobin dropped to 6.5 so he underwent transfusion. Gastroenterology was consulted and upper endoscopy was performed, which did not reveal an underlying cause. Recommendation was to proceed with pill endoscopy. His creatinine remained elevated despite fluid resuscitation and avoidance of nephrotoxic agents. Nephrology was consulted and recommended a renal ultrasound, which was largely normal. Due to persistent renal failure, he was started on dialysis. After several days of admission, antineutrophil cytoplasmic antibodies (ANCA) studies were ordered. The patient was P-ANCA positive and Ribonucleoprotein (RNP) antibody positive. Renal biopsy was performed and suggestive of Pauci-Immune Crescentic Glomerulonephritis, identifying the etiology of his acute renal failure. He proceeded with pill endoscopy which was negative for a bleeding source; suggesting the etiology of his anemia and melena was microvascular damage due to systemic vasculitis. He was started on prednisone and rituximab and discharged for outpatient dialysis with nephrology follow up.
Discussion: It is common for hospitalized patients to have symptoms attributed to multiple etiologies and it is rare to find a unifying diagnosis. This case highlights a complex presentation of Pauci-Immune Crescentic Glomerulonephritis, a form of small vessel vasculitis that is associated with necrotizing glomerulonephritis. The vast majority of patients with renal vasculitis are ANCA positive and many develop systemic symptoms. While gastrointestinal (GI) bleeding is a known complication of vasculitis, it is infrequent and often overlooked, especially in the absence of more typical symptoms, such as hematuria or pulmonary manifestations. There is a higher incidence of upper and lower airway, musculoskeletal, skin or nervous system symptoms. GI involvement including melena is less common. This patient’s presentation with melena, weight loss, anemia and rapidly progressive renal failure led to an extensive diagnostic workup, ultimately revealing a diagnosis of ANCA associated vasculitis. GI bleeding from vasculitis is usually secondary to changes in the microvasculature, rather than primary lesions. This is highlighted by endoscopy, CT and pill camera endoscopy failing to reveal GI pathology. The bleeding was ultimately attributed to microvascular damage due to systemic vasculitis.
Conclusions: This case illustrates the rare but significant association between GI bleeding and Pauci-Immune Crescentic Glomerulonephritis. Systemic vasculitis should be considered on the differential diagnosis of patients with unexplained GI bleeding and renal failure. Early recognition and prompt initiation of immunosuppressive therapy, along with supportive measures like dialysis, are essential for improving patient outcomes.