RESUMO
McKittrick-Wheelock syndrome is caused by chronic water and electrolyte hypersecretion from an intestinal tumor, usually a villous adenoma, located in the rectum or sigmoid. Patients often have dehydration, hypovolemic shock and kidney failure associated with hypokalemia, hyponatremia, hypochloremia and metabolic acidosis. We report a 62-year-old male, suffering chronic diarrhea for eight years who was admitted after a syncope. He had severe hypokalemia, hyponatremia, metabolic acidosis, hypovolemia and acute renal failure. After his metabolic disorders were corrected, a colonoscopy showed a large rectosigmoid tumor with the characteristics of a villous adenoma. During the follow up after the complete tumor resection, the patient has remained asymptomatic.