Abordagem para diarreia crônica em recém-nascidos e bebês (<6 meses)

Abstract

Introduction: During childhood, stool volumes of >20 g/kg/day are considered diarrhea. If symptoms persist for more than two weeks, it is classified as chronic. Acquired forms of chronic diarrhea result from infectious, allergic, or underlying congenital anomalies or medical disorders. If the latter require resection of significant portions of the intestine, they can lead to short bowel syndrome, with associated malabsorption and chronic diarrhea. Some cases of persistent or recurrent infectious diarrhea are caused by a primary immunodeficiency. Food protein-induced allergic proctocolitis (due to cow's milk protein) is a common benign cause of bloody stools in young babies. Objectives: discuss the causes and forms of diagnosis for chronic diarrhea in newborns and babies under six months of age. Methodology: Integrative literature review based on scientific databases from Scielo, PubMed and VHL, from January to April 2024, with the descriptors “Chronic diarrhea”, “Babies <6 months”, and “Diagnosis”. Articles from 2019-2024 (total 29) were included, excluding other criteria and choosing 5 full articles. Results and Discussion: Congenital diarrhea and enteropathies (CODEs) are uncommon but serious causes of chronic diarrhea in newborns and infants. Most CODEs are monogenic and can be categorized into genetic variants that directly affect the intestinal epithelium and impair nutrient absorption or electrolyte flow, or those that affect the immune system, which, due to inflammation, secondarily impair epithelial function. Most CODEs present with severe diarrheal symptoms that begin within the first few weeks of life, although some CODEs, particularly those caused by immune dysregulation, may present after the neonatal period. Other clinical features that raise the possibility of a CODE include membership in a population with a high frequency of certain genetic variants or consanguinity, multisystem disease (e.g., dysmorphism or other congenital anomalies or immunological deficiencies), and polyhydramnios. For most patients with suspected CODE, initial evaluation includes a battery of serum tests, stool tests, and upper endoscopy (with colonoscopy for selected patients). Some of these tests may be selected later in the evaluation based on the type of diarrhea. Standard serum testing includes complete blood count, electrolytes, erythrocyte sedimentation rate or C-reactive protein, liver function tests, and albumin. Additional tests for selected patients include a lipid panel, immunoglobulin G and A (IgG and IgA), and T and B cell subsets. Standard stool tests consist of electrolytes (to calculate an osmotic gap), pH and reducing substance, alpha antitrypsin -1, elastase, calprotectin, and culture and/or polymerase chain reaction techniques to rule out bacterial or other infectious causes. Some of these tests require special collection procedures to ensure an accurate result. Conclusion: The results of these tests inform the diagnostic steps used to determine the most likely type of CODE. For watery diarrhea, fasting tests or a carbohydrate-free formula help narrow the diagnostic possibilities. Once the likely CODE category is identified, functional testing or genomic testing can be used to confirm the specific diagnosis.