Macrolipasemia due to Crohnʼs Disease

Abstract

Purpose: In a patient presenting with epigastric pain, emesis, and elevation of lipase, a diagnosis of pancreatitis may seem inevitable. But in spite of its specificity, the elevation of lipase in the context of a normal amylase value merits further investigation into other potential etiologies. A 56-year-old female with a history of longstanding severe Crohn's disease requiring multiple small bowel resections was initially seen in 2010; remission was maintained with certolizumab pegol. However, a few months later she started to experience epigastric and periumbilical pain, so cerrtolizumab pegol was boosted and split, deferring dual therapy with a thiopuine due to prior infections. Despite initial improvement, she was admitted two months later for emesis and severe periumbilical pain; lipase was elevated at 7000 U/L with a normal amylase. She did not consume alcohol, have a history of gallbladder disease, or take any known pancreatotoxins. Ultrasound and MRI demonstrated a normal pancreas; CT suggested a slightly plump pancreas, but IgG4 was negative. Serum trypsin, urinary lipase, fecal elastase, and serum amylase were all negative or normal. Colonoscopy revealed inflammation at the ileocolonic anastomosis causing significant narrowing. Based on this investigation, it was determined that the patient had macrolipasemia due to Crohn's disease. Isolated macrolipasemia is a rare finding that has been observed in celiac disease, cryptogenic liver cirrhosis, non-Hodgkin's lymphoma, and Crohn's disease. Although significantly more uncommon than hyperamylasemia, a solitary increase in lipase values in patients without pancreatitis has been reported in the literature; there has been only one such documented case of macrolipasemia and Crohn's disease. Laboratory measurements of lipase account for all forms of the enzyme regardless of composition. Macroenzyemes are formed by either self polymerization or the creation of a complex consisting of the physiologic enzyme and immunoglobulin; there have been reports of such complexes in association with autoimmune phenomena. The increased molecular mass of these macroenzymes does not allow for physiologic filtration and removal of the enzyme via the kidney, thereby accounting for the accumulation of the enzyme in serum levels and lack of presence in the urine. Currently, no evidence has been found to suggest that macroenzymes play a compelling role in the cause of disease, nor do they require treatment. Therefore, in a patient with repeated episodes of abdominal pain and isolated elevation of lipase, consider alternatives to the diagnosis of pancreatitis, particularly when another known abdominal disease exists.