Tetany and Atrial Fibrillation Resulting from Fat Malabsorption Secondary to Tropical Sprue

Abstract

Purpose: Celiac disease, tropical sprue and tropical enteropathy are conditions that may show villous flattening in small-bowel biopsy specimens. They typically present with chronic diarrhea and malabsorption. To our knowledge, no case presenting with tetany and atrial fibrillation has been reported. Methods: A 76-year-old Hispanic man, immigrated from Domincan Republic 50 years ago, was admitted to our hospital for a 5-day history of progressive generalized muscle numbness, twitching and palpitation. The patient did not report diarrhea. On physical examination, he had an irregularly irregular pulse rate and positive Trousseau sign. Blood tests showed microcytic anemia, severe hypocalcaemia, hyperphosphoremia, hypomagnesemia, and elevated PT/INR, yet normal renal function. Vitamin D (25-OH vit D) was very low and PTH was high. Serology for tissue transglutaminase (tTG) and endomysial IgA antibody were negative. Normal serum IgA level excluded selective IgA deficiency. Electrocardiograph showed atrial fibrillation with rapid ventricular response and prolonged QT interval. Duodenal biopsy showed small bowel mucosa with increased intraepithelial lymphocytes and mild villous blunting. These changes were nonspecific but were consistent with celiac disease, tropical sprue and tropical enteropathy. Results: Tetany and atrial fibrillation resolved after treatment with electrolyte replacement and metoprolol. In light of his negative serologic antibodies and the fact that patient used to reside in the Caribbean, the diagnosis of tropical sprue was preferred over celiac disease. The patient was discharged from the hospital with 6 months of folic acid and tetracycline. On follow-up, seven months later, his symptoms had resolved and weight had increased from 128 pounds to 134 pounds. All electrolytes had remained within the normal range. Conclusion: Malabsorption should be considered in all cases of unexplained hypocalcemia, particularly in the presence of other electrolyte abnormalities, such as hypomagnesemia which can result in pseudohypoparathyroidism manifesting as hypocalcemia, elevated phosphorus, and resistance to PTH action. Nutritional deficiencies may become progressively severe in the absence of gastrointestinal symptoms in diseases with small intestinal villous atrophy, such as celiac disease or tropical sprue. Tropical sprue is the favored diagnosis in the above case, considering the patient's residence in the tropics and the absence of serological markers for celiac disease. Tropical enteropathy, although also possible, is unlikely, since it is usually diagnosed in young children.