Food allergy series: FPIES (part 2)

FPIES is usually diagnosed clinically. Endoscopy and biopsy are not necessary to diagnose, but is sometimes done to rule out other conditions.

Scopes have shown a variety of inflammatory changes in the GI tract of FPIES kids. Diffuse colitis, friable mucosa, rectal ulceration and bleeding have been observed.  Increased levels of TNFa and decreased receptors for TGF-b have been found in the GI tract. Baseline intestinal absorption is usually normal.

Biopsies have shown villous atrophy, tissue edema, crypt abscesses, increased white blood cells, including eosinophils and mast cells, and IgM and IgA containing plasma cells. Radiology showed air fluid levels (collection of both fluid and gas in the intestines), narrowing and thickening of the mucosa in the rectum and sigmoid colon and thickening of the circular folds in the small intestine. When surgery has been performed, distension of the small bowel and thickening of the jejunum has been seen.

Food specific IgE is not usually present. In one study, 21% of patients with solid food FPIES had detectable food specific IgE. 18-30% with FPIES to cow’s milk or soy have IgE for it. If IgE is found, the course of FPIES is longer. One study found a decrease in food specific IgG4 in FPIES patients along with an increase in food specific IgA.

FPIES is managed by removing the offending food. Exclusive breastfeeding can be protective. If not breastfed, use of casein hydrolysate formula is recommended. Less commonly, amino acid formula or IV fluids may be needed. Doctors recommend introducing yellow vegetables and fruits as solids rather than cereal at six months of age. Grains, legumes and poultry should be avoided for the first year of life. Once tolerance is established to one food in a high risk category, like grains, the child is more likely to tolerate other foods in the same category.

Oral food challenges (OFC) should be undertaken to determine if tolerance to the food has been achieved. A conservative approach recommends challenges every 18-24 months in patients without recent symptoms. OFCs are high risk procedures for FPIES children. The following procedure should be observed:

  • Any FPIES OFC must be physician supervised. Generally, inpatient settings are preferred, but if an outpatient setting can provide appropriate supportive care, it may be acceptable. Intravenous access should be secured prior to beginning and IV fluids and medications should be immediately available in case of reaction. ICU care is not recommended unless there is a history of near fatal reactions.
  • Blood should be drawn immediately before beginning the OFC to provide baseline complete count count and neutrophil count.
  • Over the first hour, 0.06-0.6g/kg body weight of food protein should be administered in three equal doses. It should not exceed 3g of total protein or 10g of total food or 100ml of liquid for initial feeding.
  • If patient has no reaction, give a full serving of food as determined by their age.
  • Observe patient for several hours afterward.
  • In the event of reaction, administer 20 ml/kg boluses of normal saline.
  • In the event of severe reaction, including repetitive vomiting, profuse diarrhea, lethargy, hypotension or hypothermia, administer 1 mg/kg methylprednisolone intravenously, up to 60-80mg total. About 50% of patients who react to FPIES OFCs will need IV fluids and steroids.
  • Epinephrine must be available during FPIES OFCs for treatment of hypotension and shock. In FPIES cases, epinephrine does not resolve vomiting and lethargy.
  • In children with positive skin tests and/or food specific IgE, antihistamines should also be available during OFCs.
  • Blood should be drawn six hours after OFC to compare to baseline values. If patient has diarrhea, stool guaiac tests should be done, and stool samples should be tested for white bloods, red blood cells and eosinophils in feces.

An OFC is considered either positive or negative. Positive means there is a reaction. Negative means there is not. It is positive if the patient experiences vomiting, lethargy or diarrhea in an appropriate time frame. In the absence of symptoms, if the neutrophil count is over 3500/ul, or white blood cells, frank or occult blood, and/or eosinophils are present in feces, the challenge is still considered positive.  More than 10 leukocytes/hpf in gastric juice at the 3 hour mark has been suggested as a positive marker, but needs further investigation. In the study that noted this marker, gastric juice was obtained via orogastric feeding tubes.

One study looked at the resolution of FPIES over a ten year period. 160 subjects were included in the study. 54% were male. Median age of diagnosis was 15 months. 180 OFCs were done for 82 patients, of which 30% had obtained an FPIES diagnosis based on previous OFCs. 44% of patients reacted to cow’s milk; 41% to soy; 22.5% to rice; and 16% to oat. 65% had only one food sensitivity, 26% had two, and 9% had three or more. Most had some form of atopic disease and 39% had detectable food specific IgE. 24% had IgE specific for the food causative for their FPIES reaction. Of the patients with IgE for cow’s milk, 41% of them moved from an FPIES reaction type to an IgE allergy reaction type.

60% of FPIES cases resolve by three years of age. This finding is an average and different populations see much different results. In South Korea, 90% of patients resolve by three years of age. In the US, only 25% resolve by this age. The differences observed are thought to be due to other factors, such as the frequency of food specific IgE and atopic disease. The median age for FPIES resolution depended largely on the food: 4.7 years for rice, 4 years for oat, 6.7 years for soy, 5.1 years for milk. If milk IgE was present, the patient did not become tolerant of milk during the course of study.

FPIES overwhelmingly affects very young children. However, there are rare cases of older children and adults developing FPIES at a later age. These cases involve fish and shellfish as the offending foods.

 

References:

Leonard, Stephanie, Nowak-Wegrzyn, Anna. Food protein induced enterocolitis syndrome: an update on natural history and review of management. Ann Allergy Asthma Immunol. 2011; 107:95-101.

Caubet, Jean Christoph, et al. Clinical features and resolution of food protein induced enterocolitis syndrome : 10-year experience. J Allergy Clin Immunol. 2014; 134(2): 382-389.