Congenital Diarrhea
Diarrhea is common in children under 6mo. Usually self-limited and
due to infection or food intolerance
If Red flags are present, consider congenital anatomical causes or
congenital diarrheas and enteropathies (CODEs)
Red Flags:
- Diarrhea that occurs at or shortly after birth
- Chronic, lasting >14 days
Etiologies for Diarrhea in infants
- Food Protein induced allergic proctocolitis (FPIAP) previously
called Milk-Protein Allergy or food protein induced
proctocolitis
- FPIES
- Infections
- Viral, Bacterial, Parasitic
- Post-Infectious Enteritis
- NEC
- VEO-IBD
- Anatomical
- Malrotation / Volvulus
- HD
- CIPO
- Gastroschisis
- Congenital or post-surgical Short Bowel
- CODEs
Clinical Manifestations
- Diarrhea (young infant) >20g/kg/day
- Diarrhea (Child w/ ostomy) >30g/kg/day
Diagnosis
- Labs
- CBC (anemia?, Leukocytes - infection?, Low total lymphocytes
- T or B cell deficiency?)
- CMP
- Most common - Hypokalemic metabolic acidosis
- Congenital Cl diarrhea - Hypochloremic metabolic alkalosis
- Hypoglycemia or diabetes - Mitchell-riley syndrome, or if
older immune dysregulation, polyendocrinopathy, intestinal
anendocrinosis, IPEX
- Inflammatory markers
- LFTs - cholestatic liver disease, Intestinal failure assoc
liver disease, microvillus inclusion disease,
trichohepaticenteric syndrome, familial HLH, autoimmune
enteropathy
- Albumin - low in PLE
- Lipid panel, Fat Soluble vitamins - If suspecting Fat
malabsorption
- If immunodeficiency is suspected (bloody stool, recurrent
severe infections, desquamating rash, diabetes, syndromic
appearance, other congenital anomalies, inflammatory
infiltrate in endoscopic Bx, abnormal NBS, or family history
- IgG and IgA level
- Specific T, B, and NK cell subset analysis by flow
cytometry
- If eczematous dermatitis present - evaluate for IPEX
- If acral or periorifical dermatitis - get Zn level to r/o
acrodermatitis enteropathica
- Stool (consider using saran wrap or turning the diaper inside
out to prevent absorption of liquid stool by the diaper)
- GI PCR or Culture +/- O&P to r/o infection
- Fecal Electrolytes
- Fecal Reducing substances
- pH
- Alpha-1-antitrypsin (A1AT) - elevation suggests protein loss
(low serum albumin and IG's suggest PLE)
- 72hr fecal fat collection (most accurate)
- Fecal elastase - r/o pancreatic insufficiency if >200
(can get false positive in severe watery diarrhea)
- Imaging
- Upper GI with SBFT
- EGD/Colo or flex sig
- Fasting Challenge
- While receiving IV fluids
- Withhold food x 24hrs
- If diarrhea unchanged, consider secretory or electrolyte
transport related etiology (osmotic gap <50)
- Congenital Cl diarrhea
- Congenital Na diarrhea
- VIPoma or serotonin secreting tumors
- Primary bile acid diarrhea
- If diarrhea improved, consider osmotic diarrhea (osmotic
gap >100) due to dietary component
- Carbohydrate malabsorption
- Note that osmotic gap between 50-100 may have alt cause
and may have equivical or unreliable results with fasting
challenge (e.g. epithelial structural defects)
For a full list of CODE's clinical manifestations of each and
diagnosis/treatment guidelines see
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6044208/