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Around 12% of the US population has irritable bowel syndrome (IBS), with women up to two times more likely to develop it than men. (NIDDK 2022) Stool testing is a helpful tool that can reveal important information about a patient’s gut health and help rule out other conditions. Understanding when and why to use a stool test can greatly enhance a healthcare provider’s ability to diagnose and manage IBS. 

Assessing IBS symptoms 

IBS is a common functional gastrointestinal disorder characterized by a cluster of symptoms that can be both persistent and distressing for patients, affecting their quality of life. (NIDDK 2022) Common symptoms can include: 

• Abdominal pain: Recurrent pain or cramping in the lower abdomen is a hallmark of IBS and can range from mild to severe.

• Bloating: A sensation of fullness or swelling in the abdomen often accompanies IBS and can be indicative of gut fermentation or gas retention. (Young Seo 2013)

• Chronic diarrhea: Frequent, loose, or watery stools can disrupt daily life and signal underlying issues that require further investigation.

• Constipation: Difficulty in passing stools or infrequent bowel movements can cause significant discomfort and may indicate motility problems. (NIDDK 2022)(Sarna 2010)

These symptoms can vary in intensity and frequency, making it crucial to differentiate IBS from other gastrointestinal disorders through comprehensive assessment and appropriate testing.

Bloating and abdominal pain are two common symptoms of IBS. 

Assessing patient history 

A detailed patient history of dietary patterns, medication usage, and medical history provides essential context to help identify any potential contributing factors to IBS symptoms. 

Antibiotic use

The use of antibiotics can significantly alter the gut microbiota, leading to dysbiosis. Dysbiosis, an imbalance in the gut microbial community, is often associated with IBS symptoms. (Dahiya 2023) Understanding the patient’s antibiotic history can provide insights into potential disruptions in their gut microbiome, which might need addressing as part of their treatment plan.

Diet

Diet plays a significant role in gastrointestinal health. One study found that 84% of the patients participating in that study reported diet as a symptom trigger for IBS. (Böhn 2013) Understanding a patient’s dietary habits makes it possible to identify any potential food triggers or intolerances that might exacerbate IBS symptoms. 

Common food triggers for IBS include high-fat foods, caffeine, alcohol, gluten, and certain carbohydrates that are poorly absorbed, such as those found in the FODMAP group (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols). (Alkalay 2022)(Rej 2019)

Family medical history

A family history of IBS or other digestive disorders may suggest a genetic predisposition to these conditions. (Saito 2011) Identifying familial patterns can provide a better context for a patient’s individual risk factors.

Mental health status

The gut-brain axis, a bidirectional communication system that connects the gut and brain, is a primary physiological link between IBS and mental health. (Staudacher 2023) The gut-brain axis involves interactions between the enteric nervous system (ENS), the HPA axis, and the microbiome. (Mayer 2023) This means that mental health is closely linked to gastrointestinal function. Stress, anxiety, and depression can exacerbate IBS symptoms, and conversely, the chronic nature of IBS can negatively impact a patient's mental health. (Qin 2014) 

Exploring a patient's mental health history and current psychological status can provide valuable insights. Effective management often requires addressing both the physical and psychological components of IBS, potentially involving collaboration with mental health professionals for comprehensive care.

Previous gastrointestinal disorders

A history of gastrointestinal infections can predispose patients to IBS. Post-infectious IBS is a well-recognized subtype in which symptoms develop following an acute gastroenteritis episode. (Grover 2014) Identifying such a history can help identify the origins of the patient’s symptoms and tailor their treatment plan accordingly.

Benefits of stool testing 

Stool tests are a valuable diagnostic tool for patients with IBS symptoms, offering the ability to identify dysbiosis, infections, and inflammatory markers, as well as to rule out other conditions.

Detecting dysbiosis

Analysis of the gut microbiota through stool testing can reveal imbalances in the microbial community, known as dysbiosis. Dysbiosis is commonly associated with IBS and can influence symptoms. (Teige 2024) Understanding the composition of the gut microbiota can guide recommendations for probiotics or dietary interventions to restore balance.

Stool testing can reveal valuable insights into the gut function, microbiome balance, and inflammation for accurate IBS diagnosis and treatment. 

Evaluating commensal bacteria in IBS

Commensal bacteria, the beneficial microbes residing in the gut, play a crucial role in maintaining gastrointestinal health and balance. Lactobacillus and Bifidobacterium species are vital for gut health, aiding in digestion, producing essential nutrients, and protecting against pathogens. Reduced levels of these beneficial bacteria can contribute to the symptoms of IBS, such as bloating, pain, and irregular bowel movements. Evaluating the balance of commensal bacteria helps identify dysbiosis and develop targeted probiotic or dietary interventions to restore a healthy microbiome, ultimately alleviating IBS symptoms and improving overall gut health. (Zhang 2015)

Identifying infections

Stool tests can identify the presence of pathogenic bacteria, viruses, or parasites that might be causing or contributing to a patient’s symptoms. (Kasırga 2019) This is particularly important in patients with chronic diarrhea, where infections like Clostridioides difficile or Giardia lamblia need to be ruled out. (Abedi 2022)(Hasan Abedi 2022)

By identifying or excluding the presence of infectious agents, we can ensure that appropriate treatment is administered. For example, if a patient’s chronic diarrhea is due to a bacterial infection, targeted antibiotic therapy will be necessary. (Akhondi 2023)

Identifying markers of digestive or malabsorption disorders

Conditions like celiac disease or chronic pancreatitis can lead to malabsorption and present with symptoms similar to IBS. (Montoro-Huguet 2021) Stool tests can detect signs of malabsorption, such as steatorrhea (fatty stools), prompting further diagnostic evaluations. (Azer 2023) 

Pancreatic elastase levels indicate pancreatic function, with low levels suggesting pancreatic insufficiency. Stool testing can measure pancreatic elastase levels, giving a clearer indication of a patient's pancreatic function. (Katzinger 2020) 

Additionally, stool testing can also measure short-chain fatty acids (SCFAs), which play a crucial role in colon health and energy metabolism. SCFAs are produced by the fermentation of dietary fibers by gut bacteria, and imbalances can suggest dysbiosis and impact digestive health. (Portincasa 2022)

Revealing inflammatory markers

Elevated levels of inflammatory markers such as calprotectin or lactoferrin in the stool can indicate inflammation in the gastrointestinal tract. This is crucial for distinguishing IBS from inflammatory bowel disease (IBD), which requires a different treatment approach. (Lamb 2011) 

Secretory IgA (sIgA) levels indicate gut immune function, with low levels suggesting compromised immunity and chronic infections. Along with SCFA balance, these markers collectively help pinpoint inflammatory causes of IBS-like symptoms, guiding personalized treatment plan strategies. (Jendraszak 2022)

Reviewing overall gut function

Stool tests can provide insights into the gut's overall function. This information can help identify functional disorders and guide dietary or pharmacological interventions.

By ruling out these alternate conditions and causes, stool tests enable practitioners to confidently diagnose IBS and create personalized treatment plans faster to improve patient outcomes and quality of life. 

Interpreting stool test markers

Stool test results provide a variety of diagnostic markers that require a comprehensive analysis.

Dysbiosis 

Assessing the balance of beneficial gut bacteria or disruptions in these bacteria associated with IBS symptoms guides the use of probiotics or dietary interventions to restore a healthy microbiome. (Teige 2024)

Inflammation and immunology

High calprotectin and sIgA levels signal inflammation, guiding anti-inflammatory treatments and dietary modifications. (Jendraszak 2022)(Lamb 2011)  Low sIgA levels may indicate weakened gut immunity, suggesting the need for immune support and to address chronic infections. (Jendraszak 2022)

Malabsorption and maldigestion

Low pancreatic elastase suggests pancreatic insufficiency, which may require enzyme supplementation. (Katzinger 2020) Elevated fecal fat indicates fat malabsorption, suggesting the need for dietary adjustments or digestive support. (Azer 2023) 

SCFAs

Crucial for colon health and energy metabolism, SCFAs are produced by gut bacteria from dietary fibers. Imbalances can indicate dysbiosis, prompting the use of prebiotics or dietary changes to restore gut balance and improve digestive health. (Portincasa 2022)

By interpreting these markers, healthcare providers can develop targeted treatment strategies tailored to an individual’s specific gut health needs. Read more about how to interpret different stool test markers in part two of this article. 

Supporting IBS patient outcomes with stool testing

IBS has a major effect on quality of life, and stool testing is the most effective way to identify underlying causes, rule out other conditions, confirm the diagnosis, and provide effective treatment. Integrating stool tests into your clinical practice is a vital component in supporting patient outcomes and ensuring personalized treatment plans can be developed as quickly as possible.