History and exam
Key diagnostic factors
common
presence of risk factors
Age >50 years, cigarette smoking, female sex, and presence of autoimmune disorders are strong risk factors for microscopic colitis.
Other diagnostic factors
common
uncommon
abdominal pain
A concomitant symptom of diarrhea reported less frequently than fecal urgency, fecal incontinence, and nocturnal stools, and with varying prevalences reported in studies.[6]
weight loss
A concomitant symptom of diarrhea with varying prevalences reported in studies. Occurs due to fluid loss and/or reduced oral intake.[6]
bloating
A concomitant symptom of diarrhea with varying prevalences reported in studies.[6]
fatigue
A nonspecific and less common symptom of microscopic colitis that may be associated with impaired quality of life. May be caused by night-time diarrhea.
Risk factors
strong
age >50 years
Microscopic colitis is more common in older adults (>50 years), and accounts for almost 20% of cases of chronic diarrhea in patients >70 years.[11][12] In one multicenter prospective study, age >50 years independently predicted risk of microscopic colitis.[43] A subsequent systematic review and meta-analysis showed a median age at diagnosis for collagenous colitis of 64.9 years, similar to lymphocytic colitis (median 62.2 years); a raised incidence of microscopic colitis was observed with increased age.[10]
cigarette smoking
Smoking cigarettes has been associated with an increased risk of microscopic colitis and persistent disease with lower probability of achieving clinical remission.[44][45][46]
In one case control study of 340 patients with microscopic colitis, any cigarette smoking (current or former) was associated with an increased risk.[44][46] A subsequent systematic review and meta‐analysis showed a significantly increased risk of microscopic colitis in current smokers compared with never smokers (odds ratio 2.99, 95% CI 2.15 to 4.15).[47]
female sex
The risk of developing microscopic colitis is higher in women than in men.[10] In three large studies from Sweden, Denmark, and the Netherlands, the proportion of females among those with microscopic colitis was on average 72%.[17][18][19] In subgroup analyses of 19 studies within a meta-analysis, female sex was associated with a significantly higher risk of microscopic colitis (pooled odds ratio 2.52, 95% CI 2.28 to 2.79).[6][10]
Case series studies have reported a female to male incidence ratio of 2.8 to 4.1 for collagenous colitis, and 1.7 to 2.6 for lymphocytic colitis.[17][19][20]
autoimmune disorders
People with certain autoimmune disorders such as celiac disease, hypothyroidism, rheumatoid arthritis, or hyperthyroidism are at higher risk of developing microscopic colitis.[9][21] In particular, there is a strong association with celiac disease. Patients with celiac disease have a 50- to 70-fold increased risk of developing microscopic colitis; conversely, 2% to 9% of patients with microscopic colitis are found to have celiac disease.[22][23] For this reason, patients with suspected microscopic colitis should be screened for celiac disease.[6]
weak
use of certain medications
Chronic or frequent use of nonsteroidal anti-inflammatory drugs (NSAIDs), proton-pump inhibitors (PPIs), selective serotonin-reuptake inhibitors, statins, and H2 antagonists has been associated with an increased risk of microscopic colitis.[24][25][26][27][28][29][30] NSAIDs, which are more strongly associated with microscopic colitis, are thought to increase this risk by inhibiting anti-inflammatory prostaglandins and changing epithelial barrier permeability.[31][32]
Despite studies suggesting an association, however, this does not imply causation. In addition, there is a lack of convincing pathophysiologic explanations, and results from one multicenter study were conflicting for PPIs and H2 antagonists.[33] It is possible that these drugs do not cause microscopic colitis, but rather worsen diarrhea and bring the diagnosis to attention.[6]
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