A typical patient with microscopic colitis will present with non-bloody, watery diarrhea that has been present for some time. As this condition definitively presents with chronic diarrhea, symptoms should be present with that definition which is three or more loose or watery stools daily lasting more than 4 weeks. Typically, the patient presenting with these symptoms will be middle-aged or older, and female, however, this can present anytime in life and both genders. Symptoms are normally between four to nine watery bowel movements daily, though there have been reports of severe disease with 15 or more bowel movements daily. Associated symptoms can be fecal urgency, incontinence, nocturnal episodes, and half of the patients will have abdominal discomfort or pain. As this is a form of inflammatory bowel disease, there are reports of other manifestations such as arthralgia, arthritis, and/or uveitis. Between the primary two types of microscopic colitis, collagenous colitis seems to be associated with more severe bowel inflammation and lymphocytic colitis appears to occur earlier in life.[25]

Hematological laboratory findings in microscopic colitis are nonspecific and typically will not guide you. Half of the patients will have an elevated erythrocyte sedimentation rate, mild anemia, and positive autoantibodies.[25] These antibodies include rheumatoid factor, antinuclear antibodies, antimitochondrial antibodies, and antithyroid antibodies.[26] While some levels of inflammatory markers, eosinophil protein X, it appears that myeloperoxidase and tryptase are elevated and/or detected in the stool of patients, but these findings have not yet received validation at this time.[27] Occasionally a patient will have a protein wasting form of diarrhea associated with hypoalbuminemia, and an albumin level should be a consideration.

Stool studies for evaluation should include Clostridium difficile toxin, stool cultures, Escherichia coli O157: H7 testing, microscopy for ova and parasites, and a Giardia stool antigen test. Additional testing to be considered can include celiac disease serology (tissue transglutaminase IgA antibody). In most cases, all stool studies described above will be negative, leading to further diagnostic evaluation.[28]

Endoscopic evaluation with mucosal biopsies is the next step of evaluation; this also will typically establish the diagnosis. The procedure of choice is a colonoscopy, with biopsies performed in the left and right colon. During endoscopy, the appearance of the colon tends to be normal, though there can be edema, erythema, friability, exudative lesions, or scarring. Microscopic colitis diagnosis is dependent upon biopsy and histopathological findings.[29]

The goal of management is to achieve remission, defined as less than three stools daily and no watery stools, and to improve quality of life. The first aspect of management is to stop any possible offending agents causing symptoms, which includes some medications, including nonsteroidal anti-inflammatory drugs, and to avoid and/or stop smoking.[30]

Initial management of symptoms includes antidiarrheal agents such as loperamide.[31] These medications alone may be enough to control symptoms, but other medicines may be necessary for control. When using these medications, it is essential to complete an infectious workup first, as they can worsen symptoms of C. difficile infection. If the patient continues to have three or more stools daily with at least one being watery, the addition of a glucocorticoid such as budesonide is a recommended therapy. With budesonide, 6 to 8 weeks of therapy is typically necessary for complete resolution.[32] After this duration of therapy, the drug must be tapered. A typical dose starts at 9mg daily. Prednisone is another glucocorticoid that is an option for therapy; however, current research indicates that budesonide is more effective.

If patient symptoms continue despite the above therapy, additional agents may be needed. Cholestyramine at a dose of 4g four times per day may help until diarrhea resolves. Cholestyramine is a bile acid binding resin utilized for diarrhea with concurrent bile acid malabsorption, which can occur. If diarrhea continues to persist after 2 weeks, bismuth subsalicylate can be given at a dose of 524mg (3 tabs) 3 times daily.[33]

Some patient will continue to have symptoms despite the above treatment. It is important to realize that approximately 10 to 20 percent o patients are non-responders.[34] Other therapies then need to be pursued. Anti-tumor necrosis factor and immunomodulators currently have limited evidence from case series and need further research. Surgery is a mode of therapy reserved for patients that are refractory and intolerant to symptoms.

Currently, maintenance therapy is not recommended secondary to side effects with budesonide. However, if this is necessary, the lowest dose possible should be utilized, and the dose should not exceed 6mg daily. Patients can be treated intermittently with budesonide to induce remission as well.

Celiac disease can have a similar symptom profile of chronic diarrhea. Celiac disease should be tested for by serologic testing. If necessary, this can also be tested for by small bowel biopsy, which shows flattening of villi.

Crohn disease is an inflammatory bowel disease that typically will cause diarrhea. This particular disease typically will present with patchy colitis and has various other characteristics such as perianal disease, like fistulas of fissures. On biopsy, granulomas are generally present along with transmural inflammation.

Irritable bowel syndrome (IBS) that is diarrhea-predominant is also a consideration. IBS is typically considered a diagnosis of exclusion. Typically, symptoms of IBS include not only diarrhea but crampy abdominal pain that is improved by defecation and frequent changes in the consistency and frequency of bowel movements.

Many patients with microscopic colitis will have a chronic, intermittent course of disease symptoms. Diarrhea can sometimes resolve without treatment or will often resolve with treatment within weeks. Relapses of symptomatology are frequent. It is currently unclear if one form is worse than the other. At present, there is no associated increased risk of colorectal cancer with microscopic colitis.

Currently, there are no known complications of disease progression itself outside of recurrent symptoms. The primary concern would be complications of therapy with budesonide as this is a steroid with multiple complications associated with long term use.[35]

Microscopic colitis is one of the many causes of chronic diarrhea. It is diagnosed based on biopsy results obtained during colonoscopy. Symptom control and remission generally occur with medication management, but some patients will not find relief. Surgery is an option but should be avoided unless symptoms are severe and intolerable. Patients will typically have three3 or more bowel movements daily most of which are watery, and most patients will have at least nine bowel movements daily. The goal of therapy is three or fewer bowel movements daily with no watery bowel movements. Some known provoking factors of this disease include tobacco use, particularly smoking cigarettes, and NSAID use. Patients should be encouraged to stop smoking and to decrease or stop the use of non-steroidal anti-inflammatory agents such as ibuprofen. There is not currently a known association with an increased risk of colon cancer. Expect symptoms to recur, though it is important to note any change in symptoms for further evaluation.

Chronic diarrhea has an extensive differential diagnosis that includes microscopic colitis. It is imperative for nursing staff to be aware of a patient complaining of chronic diarrhea what the consistency, color, and associated symptoms are to advocate for further evaluation. A gastroenterologist will also be involved in these cases for evaluation. If the patient workup as an outpatient, depending upon the workup already performed the GI specialist will be instrumental in completing the workup with colonoscopy and biopsies. Primary care physicians and nurse practitioners will be the point of care leaders to diagnose and begin the workup. Pharmacists will be helping with the recommendation for antidiarrheal agents when it is known that the cause is not infectious, and for further recommendations for glucocorticoids.[36][37](Level II) All these disciplines need to work together as an interprofessional team to bring about optimal diagnosis, care, and clinical outcomes. [Level V]