A 4-week-old girl is brought to the office after her parents noticed bright red blood in the stool this morning. The stool was looser than normal and had streaks of blood in it. The patient also has been fussier than usual with feeds over the past day. There have been no changes in her intake, which consists of a standard cow's milk-based formula taken every 3 hours. The patient was born at full term following an uncomplicated delivery. Her weight is tracking along the 50th percentile. Vital signs are normal. She is alert and well appearing. The remainder of the examination is normal. Which of the following is the most likely cause of this patient's gastrointestinal symptoms?

Question

A 4-week-old girl is brought to the office after her parents noticed bright red blood in the stool this morning.  The stool was looser than normal and had streaks of blood in it.  The patient also has been fussier than usual with feeds over the past day.  There have been no changes in her intake, which consists of a standard cow's milk-based formula taken every 3 hours.  The patient was born at full term following an uncomplicated delivery.  Her weight is tracking along the 50th percentile.  Vital signs are normal.  She is alert and well appearing.  The remainder of the examination is normal.  Which of the following is the most likely cause of this patient's gastrointestinal symptoms?

Quizplus · Accepted Answer

11ec25c8_d5f9_d6a9_bc81_27cf2a186830_MD0003_00 This well-appearing infant with loose, blood-streaked stools most likely has food protein-induced allergic proctocolitis (FPIAP), a self-limited condition of early infancy. FPIAP is a non-IgE-mediated reaction in which a protein in the infant's diet (breast milk or formula) causes eosinophilic inflammation of the distal colon and rectum. Cow's milk (eg, casein, whey) and soy proteins are the most frequent triggers. The most common presentation is bloody stools that develop weeks to months (most commonly at age 1-4 weeks) after initial exposure to the offending food protein. Patients may have some associated fussiness but are generally well appearing with normal growth. FPIAP is a clinical diagnosis. It is confirmed by symptom resolution after a period of avoiding the food allergen (eg, switching to a hydrolyzed formula). Patients typically tolerate products containing the offending protein (eg, milk, yogurt) by age 1. (Choices A and D) Inflammatory bowel disease can be associated with granulomatous and neutrophilic inflammation of the intestines. Presentation is very rare in infants and typically includes severe, bloody diarrhea, fever, and weight loss. This patient's normal growth and examination make this diagnosis unlikely. (Choice B) IgA autoantibody reactivity to tissue transglutaminase contributes to the pathogenesis of celiac disease, which causes nonbloody diarrhea, abdominal pain, and failure to thrive. This condition is rare in infants prior to starting solid food because formula is gluten free. (Choice C) An IgE-mediated food allergy is an immediate hypersensitivity reaction caused by histamine release from activated mast cells. Symptoms typically occur within minutes (up to an hour) of food ingestion and most commonly include urticaria and angioedema, although multiorgan system involvement (eg, vomiting, hypotension, wheezing) can occur. This patient's isolated gastrointestinal bleeding is inconsistent with this diagnosis. Educational objective: Food protein-induced allergic proctocolitis is a non-IgE-mediated reaction to a protein (typically cow's milk or soy) that presents with bloody stools in well-appearing young infants. References: Food protein-induced enterocolitis syndrome and allergic proctocolitis. (http://www.ncbi.nlm.nih.gov/pubmed/25976434) Non-IgE-mediated gastrointestinal food allergy. (http://www.ncbi.nlm.nih.gov/pubmed/25956013)

A 4-Week-Old Girl Is Brought to the Office After Her