What tests are recommended for diagnosing gastrointestinal symptoms, specifically diarrhea and dyspepsia (indigestion)?

From the Guidelines

For diarrhea and indigestion, the most appropriate initial tests include stool analysis, blood tests, and possibly endoscopy depending on symptom severity and duration. A stool sample should be collected to check for parasites, bacteria (like Salmonella, E. coli, C. difficile), blood, and fat content. Blood tests including complete blood count, metabolic panel, celiac antibodies, and inflammatory markers (CRP, ESR) can help identify underlying causes. If symptoms persist beyond 2-3 weeks or are accompanied by warning signs like weight loss, severe pain, or blood in stool, an upper endoscopy and/or colonoscopy may be necessary to visualize the digestive tract directly. Hydrogen breath tests can identify lactose intolerance or small intestinal bacterial overgrowth if suspected. Imaging studies such as abdominal ultrasound or CT scan might be ordered if structural issues are suspected. These tests help determine whether the symptoms are caused by infection, inflammation, malabsorption, food intolerance, or other digestive disorders, allowing for appropriate targeted treatment rather than just managing symptoms.

Some key considerations for testing include:

• Stool testing should be performed for Salmonella, Shigella, Campylobacter, Yersinia, C. difficile, and STEC in people with diarrhea accompanied by fever, bloody or mucoid stools, severe abdominal cramping or tenderness, or signs of sepsis 1.
• Blood cultures should be obtained from infants <3 months of age, people of any age with signs of septicemia or when enteric fever is suspected, people with systemic manifestations of infection, people who are immunocompromised, people with certain high-risk conditions such as hemolytic anemia, and people who traveled to or have had contact with travelers from enteric fever–endemic areas with a febrile illness of unknown etiology 1.
• A broader set of bacterial, viral, and parasitic agents should be considered regardless of the presence of fever, bloody or mucoid stools, or other markers of more severe illness in the context of a possible outbreak of diarrheal illness 1.
• Diagnostic testing is not recommended in most cases of uncomplicated traveler’s diarrhea unless treatment is indicated 1.
• Clinical consideration should be included in the interpretation of results of MP-NAAT because these assays detect DNA and not necessarily viable organisms 1.

It's also important to note that the choice of diagnostic test may depend on the clinical context and the suspected underlying cause of the symptoms. For example, if C. difficile infection is suspected, stool testing for toxin A and B or nucleic acid amplification tests (NAATs) may be performed 1. Ultimately, the goal of testing is to identify the underlying cause of the symptoms and guide appropriate treatment.

From the FDA Drug Label

The adverse events with an incidence of 1. 0% or greater, which were reported at least as often in patients on loperamide hydrochloride as on placebo, are presented in the table below. Gastrointestinal AE% Constipation 2.6% 0.8% The adverse events with an incidence of 1. 0% or greater, which were more frequently reported in patients on placebo than on loperamide hydrochloride, were: dry mouth, flatulence, abdominal cramp and colic.

Diarrhea and indigestion tests are not explicitly mentioned in the provided drug label as tests to be done. The label discusses the adverse effects of loperamide hydrochloride, which include gastrointestinal symptoms such as constipation, dry mouth, flatulence, abdominal cramp, and colic.

• Key symptoms associated with the use of loperamide hydrochloride include:
  • Constipation
  • Dry mouth
  • Flatulence
  • Abdominal cramp
  • Colic However, the label does not provide information on specific tests for diarrhea and indigestion 2.

From the Research

Diarrhea and Indigestion Tests

• The tests for diarrhea and indigestion depend on the duration and severity of symptoms, as well as the presence of alarm features 3.
• For patients with nosocomial diarrhea, stool cultures and ova and parasite testing are not recommended, as they are often low-yield and can be costly 4, 5.
• A clinical approach to diarrhea involves taking a thorough history, performing a physical examination, and evaluating stool characteristics, such as consistency, frequency, and presence of blood or fat 6.
• The evaluation of chronic diarrhea may involve testing, including stool exams, endoscopy, imaging studies, and physiological testing, but not all tests are necessary for every patient 3.
• A rational approach to the stool ova and parasite examination suggests that examining a single specimen is sufficient for most patients, especially when the prevalence of infection is low 7.

Specific Tests

• Stool cultures are not recommended for patients with nosocomial diarrhea, as they are often negative and can be costly 4, 5.
• Ova and parasite testing is also not recommended for patients with nosocomial diarrhea, as it is often low-yield and can be costly 4, 5.
• The fecal osmotic gap test can help characterize chronic diarrhea as osmotic or secretory 6.
• Steatorrhea (fatty diarrhea) can be diagnosed with tests that differentiate between malabsorption and maldigestion states 6.