2025 – PAGE 235 – GASTROENTEROLOGY

CAUSES OF DIARRHEA

CHRONIC NONSPECIFIC DIARRHEA

Chronic nonspecific diarrhea is very common. The patient presents with malodorous stool that is often intermittently loose and may contain particles of food. This is usually seen in children with a diet that is low in fat and high in carbohydrates. Treat by increasing fat intake and decreasing carbohydrates.

(DOUBLE TAKE) LACTOSE INTOLERANCE (AKA LACTASE DEFICIENCY)

It is not common for kids < 5 years old to have lactose intolerance (AKA lactase deficiency). So, for the pediatric boards, if the child is less than 5 years of age, suspect a different diagnosis!

• SYMPTOMS: Diarrhea ± abdominal pain.
• The HYDROGENBREATH TEST can be used to help diagnose a lactase deficiency (as well as bacterial overgrowth). When the patient takes a carbohydrate load; if he or she is unable to digest the carbs because of a lack of lactase, the bacteria will digest the carbs and release hydrogen (which can be measured in the breath).
• TREATMENT: SOY milk. It does not contain lactose. It contains sucrose.
• PEARLS: Stool is NOT malodorous and does NOT have food particles. These patients do NOT vomit and do NOT have an associated rash. consider the diagnosis of an ALLERGY if you’re presented with a patient with such symptoms.
• MNEMONICS: “LACTose comes from the LACTating breasts of women and cows, NOT from soy beans.”

BACTERIAL OVERGROWTH

Bacterial overgrowth is often seen in children with short bowel syndrome and will result in malabsorption. As mentioned above, an elevated fasting breath HYDROGEN test can make the diagnosis. Diagnosis is also supported by an elevated D-lactic acid level (not L-lactic acid level).

CELIAC DISEASE (AKA CELIAC SPRUE)

Classic symptoms of celiac disease (AKA celiac sprue) include malodorous stool that is bulky and frothy. The patient may also have a distended abdomen and signs of malabsorption. Patients have an autoimmune sensitivity to GLUTEN. Malabsorption may be evidenced by noting reducing substances in the stool (caused by patchy villous atrophy of the GI mucosa leading to lactase deficiency), or noting split fats in the stool (indicates the pancreas is working and there is adequate lipase, but malabsorption is present). Supportive blood tests include the presence of anti-endomysial antibodies, anti-Tissue TransGlutaminase (anti-TTG is much more sensitive, similarly specific, and easier for labs to process), and the newer anti-deamidated gliadin peptide (DGP) assays (highest specificity). The gold standard for diagnosis is upper endoscopy and duodenal biopsy showing villous atrophy. Treat with a gluten-free diet.

PEARL: This is often associated with T1DM. If presented with a DM patient that is having GI symptoms, or is losing weight, consider CELIAC DISEASE.

INFECTIOUS DIARRHEAL ILLNESSES

SEE ID SECTION FOR AN EXTENSIVE LIST OF INFECTIOUS DIARRHEAL ILLNESSES