Giovanni Addolorato

Chronic diarrhea in a patient with severe vitamin B12 deficiency: a rare clinical manifestation

A 65-year-old woman was admitted to our Internal Medicine Unit because of diarrhea (seven evacuations of loose stools/day, with no blood or mucus) and progressive fatigue for about a year. Fatigue had progressively worsened up to the inability to perform daily activities. She suffered from diabetes, treated with metformin (1 g tid) and aspirin. She did not take any new drugs and did not change her lifestyle. At physical examination, vital signs, cardiopulmonary, abdominal, and neurological evaluations were normal, except for mucocutaneous paleness and tongue smoothness. Complete blood count showed macrocytic anemia (Hb: 9.8 mg/dl, MCV: 109 fl) that was not present 2 years before. Electrolytes, kidney, liver, thyroid tests, and urinalysis were normal as well as acute phase proteins, ferritin, and iron levels. Three samples of stool (physical and microbiological) were normal. Upper and lower bowel endoscopy and small bowel barium-X-ray showed no alterations. A severe vitamin B12 deficiency was evidenced (5125 pg/ml, n.v. 187–883 pg/ml) with normal folates (5.5 ng/ml, n.v.44 ng/ml).[1] Antibodies against intrinsic factor and transglutaminases were absent. Cyanocobalamin i.m. was started (1000mg/day for 7 d, then weekly for 8 weeks, then monthly).[2] About 24 h after the first administration of cyanocobalamin diarrhea resolved. Two months later fatigue had disappeared and laboratory tests were normalized (Hb: 13.5 g/dl, MCV: 86 fl).