Gastrointestinal Amyloidosis Presenting as Hyponatremia

Abstract

Gastrointestinal (GI) amyloidosis is a rare disease defined by the deposition of insoluble protein fragments along the GI tract, impeding proper tissue function. The clinical presentation of GI amyloidosis is often non-specific and can include nausea, abdominal pain, nutritional deficiency, and diarrhea. Multiple epidemiologic studies have shown this disease to have a rare prevalence. We present a case of GI amyloidosis presenting as hyponatremia and its course of management. A 78-year-old male was sent to our hospital by his primary physician for evaluation of hypotension and hyponatremia. The patient reported a severely decreased oral intake for several weeks and had new lower extremity edema for which he was receiving diuresis. The patient showed evidence of failure to thrive alongside symptoms of decreased appetite, abdominal pain, constipation, and nausea. An upper endoscopy was performed which revealed edematous, friable, and ulcerated mucosa (Fig. 1). Histologic analysis showed amyloid deposition in the small intestine with positive Congo red staining. A diagnosis of amyloidosis was further confirmed by fat pad biopsy. Mass spectrometry showed kappa light chain amyloid, consistent with AL amyloidosis. Supportive therapy was administered and he was later placed on chemotherapy as an outpatient. The patient's weight has continued to fluctuate over time and there has been ongoing discussion over the need for and utility of a percutaneous endoscopic gastrostomy (PEG) tube versus total parenteral nutrition (TPN) as a means for nutritional support.Diagnosis of GI amyloidosis is often delayed due to the variety of signs and symptoms that may present. A presentation of hyponatremia due to overdiuresis for edema is unique for GI amyloidosis. This patient's decreased oral intake in the setting of malabsorption, all likely related to his amyloidosis, correlated to a low albumin level and consequential edematous state. Overdiuresis led to the presenting symptom of hyponatremia. Currently, there is no treatment specific for GI amyloidosis, with care directed at targeting the underlying etiology of the amyloid protein while providing supportive therapies and nutritional support. There has been little discussion in the literature on PEG tube placement or TPN for GI amyloidosis, an ongoing consideration for our patient. Prognosis is dependent upon the amyloidosis subtype and extent of organ involvement, and has shown improvement over recent years.2515 Figure 1 No Caption available.