Based on the information so far, it is reasonable in this patient to evaluate for celiac disease and for microscopic colitis.
Celiac disease, also called gluten-sensitive enteropathy, has a varied presentation that includes nonspecific symptoms such as those in this patient. Classically, it causes diarrhea, but patients may present with a single nutrient deficiency and no diarrhea.
This patient lacks the elevated alkaline phosphatase or evidence of vitamin deficiencies characteristic of malabsorption in celiac disease (ie, vitamins A, B 12, D, K, and folate) 3. She also lacks evidence of malnutrition, such as iron deficiency anemia, weight loss, or low serum albumin. Finally, she does not have the dermatitis herpetiformis rash to suggest autoimmune gluten-sensitive enteropathy, nor does she have evidence of follicular hyperplasia or petechiae due to vitamin malabsorption. 3
Because no single serologic test is ideal for diagnosing gluten-sensitive enteropathy, several tests are typically used: immunoglobulin A (IgA) antigliadin antibody, IgG antigliadin antibody, IgA antitransglutaminase antibody, and IgA antiendomysial antibody. IgA antitransglutaminase antibody is 92% to 98% sensitive and 91% to 100% specific for celiac disease. IgG antigliadin antibody is 92% to 97% sensitive and 99% specific. The positive predictive value of the IgA and IgG antigliadin antibody tests is less than 2% in the general population, whereas the positive predictive value for antiendomysial antibody and antitransglutaminase antibody are 15.7% and 21.8%, respectively. 4 A positive serologic test for antiendomysial antibody is nearly 100% specific.
Our patient’s entire celiac antibody panel is negative, and thus celiac disease is unlikely.
Case continued: Features of microscopic colitis
In our patient, colonic biopsy reveals a mildly expanded lamina propria, intraepithelial lymphocytes, and a patchy but prominent thickening of the subepithelial collagen table. This set of features is consistent with collagenous colitis, a variant of microscopic colitis. Histologic signs on biopsy specimens are fairly specific for the disease. 5
Chronic, intermittent, secretory diarrhea without bleeding is the hallmark of microscopic colitis. Associated symptoms may include abdominal pain, weight loss, and fatigue. If biopsies are not taken at the time of the initial evaluation, and the colonic pathology is overlooked, patients with collagenous colitis may be diagnosed with irritable bowel syndrome with diarrhea. 6 The sedimentation rate is often elevated, and the antinuclear antibody test can be positive. 7 Steatorrhea or protein-losing enteropathy can occur, and fecal leukocytes are present in more than 50% of patients. 8
This patient fits well the demographics of the typical collagenous colitis patient: ie, a middle-aged woman in her 6th decade in otherwise good general health. The female-to-male ratio is 15:1 overall, although the relative frequency of collagenous colitis in women is greater than that of lymphocytic colitis. 9 In a population-based study, the incidence of collagenous colitis was 5.1 per 100,000 per year, with a prevalence of 36 per 100,000; the incidence of lymphocytic colitis was 9.8 per 100,000 per year, with a prevalence of 64 per 100,000. 10
Symptoms are typically vague and range from an annoyance to more than 20 non-bloody stools per day. The course of the disease also varies. Case series have reported a spontaneous remission rate of 15% to 20%, 11 though flare-ups are common. Microscopic colitis is largely a benign disease. It does not increase a person’s risk of colon cancer.