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Food allergy testing is an inexact science — could a new blood test help?
Severe food allergy reactions are associated with α-tryptase; The Journal of Allergy and Clinical Immunology, October 2023.
Doctors test for food allergies through a variety of methods. Skin sensitivity tests are most common but are not without risk. Elimination diets for children take time and are only as good as a parent’s understanding of food ingredients.
Now, according to a study published this month in The Journal of Allergy and Clinical Immunology, a novel blood test can identify children at risk for severe allergic reactions to foods.
Researchers led by Dr. Abigail Lang at the Ann & Robert H. Lurie Children’s Hospital of Chicago, tested the blood from 119 subjects for a gene, TPSAB1, which instructs the body to produce a protein, alpha-tryptase (⍺-tryptase), associated with severe allergic reactions.
Measuring blood levels of ⍺-tryptase directly is also an option, but the protein does not last long in the blood and levels do not always correlate with symptom severity.
Lang and coworkers hypothesized that measuring the capacity to produce ⍺-tryptase through genetic testing, and not actual protein levels at specific time points, might be more predictive.
Eighty-two children (average age 9) were part of a larger observational food allergy study while 37 (average age 3) had a confirmed peanut allergy.
Among the 82 children in the observational group, the ⍺-tryptase gene was associated with a higher incidence of life-threatening food-triggered anaphylaxis during the study period.
Among children with a confirmed peanut allergy, 20 of 31 (65%) with the α-tryptase gene had a severe reaction.
Children carrying the gene also tended to have worse symptoms, and those with multiple copies of TPSAB1 fared the worst.
Although the TPSAB1 test does not predict future severe food reactions perfectly, it provides doctors with an additional way to help guide children’s families on healthy dietary choices.
Food allergies affect 1 in 10 U.S. adults and 1 in 13 children, with 200,000 Americans every year requiring emergency medical care. Testing for food allergies is an inexact science, but this blood test could identify individuals at the greatest risk for anaphylaxis.
Is your child really allergic to penicillin?
Multisite oral amoxicillin challenges during pediatric emergency department visits; JAMA Pediatrics, Oct. 2, 2023.
About 10% of children seen in emergency rooms (ERs) have a parent-reported allergy to penicillin and similar drugs, which limits options when antibiotic treatment is warranted.
But many of these children are not allergic at all, according to a study published this month in JAMA Pediatrics, led by Dr. David Vyles, at the Medical College of Wisconsin, Milwaukee.
Researchers approached 1,189 parents of children ages 2-16 admitted to three Midwest U.S. ERs with a penicillin allergy questionnaire.
From 372 completed questionnaires, they selected 117 children with mild allergy whose parents consented to the child taking an oral penicillin challenge to confirm the allergy.
Children with a history of developmental delays and those presenting with a rash, vomiting, or asthma symptoms were excluded, as were those who were so sick they required immediate hospitalization.
The oral challenge consisted of a 500-milligram dose of oral amoxicillin in pill form or a 520-milligram liquid dose for patients unable to swallow pills. Children were observed for one hour and re-evaluated the following day.
In 98% of the cases, the child turned out not to be allergic.
Also called beta-lactam antibiotics, penicillins include several chemically related drugs, for example amoxicillin (brand name Amoxil), ampicillin (Unasyn) and oxacillin (Bactocill).
Children allergic to penicillin tend to require more expensive antibiotics and have worse outcomes, so determining the true allergic status is in everyone’s interest.
Vyles concluded that oral penicillin challenges could be especially useful for children “in need of acute antibiotics,” but the day-long timeframe for the oral challenge test remains an issue.
Skin rashes: the right diagnosis matters
Prevalence of allergic contact dermatitis in children with and without atopic dermatitis: A multicenter retrospective case-control study; Journal of the American Academy of Dermatology, Sept. 25, 2023.
Contact and atopic dermatitis both involve skin rash, and their treatments overlap to a degree. However, differences in treatment make it important to get the diagnosis right.
Atopic dermatitis is a chronic condition arising from complex immunologic processes with a likely genetic component. People with atopic dermatitis tend to have asthma, other allergies or a related family history.
Contact dermatitis also involves the immune system but is generally a response to one or a very narrow range of irritants, for example, poison ivy or ingredients in personal care products.
Overcoming contact dermatitis may involve no more than identifying and avoiding the irritant, while atopic dermatitis is treated with immune-suppressing medicines like topical corticosteroids.
A study published last month in the Journal of the American Academy of Dermatology suggests contact dermatitis is underdiagnosed in children with atopic disease.
Investigators led by Dr. JiaDe “Jeff” Yu, at Massachusetts General Hospital, Boston, concluded children with atopic dermatitis may benefit from skin patch testing to see if some of their symptoms may be a result of contact exposure to irritating substances.
The researchers examined 912 children for skin rashes — 615 with atopic dermatitis and 297 without.
Children in the atopic group averaged 4.1 years with symptoms compared with 1.6 years for non-atopic kids.
Atopic subjects also had slightly more positive skin tests than the non-atopic group, more rash-affected areas and higher allergic responses to common skin irritants. These findings led investigators to conclude that children with atopic dermatitis also should be tested for contact dermatitis to uncover “potentially relevant contact allergens.”
Hidden dangers in off-the-field concussions
Post-injury outcomes following non-sport-related concussion: A CARE Consortium Study; Journal of Athletic Training, Sept. 8, 2023.
Young people who suffer head injuries outside of organized training or games do not receive appropriate medical attention, according to a study published last month in the Journal of Athletic Training.
The 20-author paper, with lead investigator Kristy B. Arbogast, Ph.D., at the Children’s Hospital of Philadelphia, reported on clinical outcomes among 3,500 college-age students who experienced head trauma — 2,945 students were injured during organized sports and 555 suffered their injury in non-sport activities. Females made up 42.5% of the subjects.
Data were collected through the joint National Collegiate Athletic Association-U.S. Department of Defense Grand Alliance Concussion Assessment, Research, and Education (CARE) Consortium, a large, ongoing concussion research effort.
Investigators looked for whether the incident was immediately reported, plus several post-injury health outcomes: changes in mental status, loss of consciousness, amnesia, motor impairment, delayed symptom presentation and hospitalization.
The outcomes were further categorized by duration of concussion symptoms and days lost to injury. Athletes were queried between 24 and 48 hours after they returned to play.
Athletes with off-the-field injuries were 27% less likely to report their injury immediately and 17% more likely to report delayed symptoms.
They were also at 77% greater risk for retrograde amnesia, and experienced motor impairment 45% more frequently. They also reported greater symptom severity, plus more days with symptoms and lost to injury relative to students with on-the-field injuries.
Among those injured off-the-field, females reported greater symptom severity, more days with symptoms and more days lost compared with males.
The authors provided very little insight into why they observed these effects. An obvious explanation is that athletes participating in sanctioned activities at the college level almost always receive immediate, appropriate medical attention while those suffering similar injuries during non-sports activities do not.
Better testing for kids with celiac?
Gluten Immunogenic Peptides Are Not Correlated With Reported Adherence to Gluten-Free Diet in Children With Celiac Disease; Journal of Pediatric Gastroenterology and Nutrition, August 2023.
Children with celiac disease who continue to show symptoms despite dietary changes are sometimes tested to see how well they are sticking to a gluten-free diet.
According to a report published in August in the Journal of Pediatric Gastroenterology and Nutrition, these tests, which measure gluten-associated peptides — breakdown products — in urine and stool, do not agree with self-reported adherence to a gluten-free diet.
Researchers led by Dr. Anat Guz-Mark, a celiac disease specialist at Tel Aviv University, Israel, enrolled 74 children — 63.5% females, average age 9 — who followed a gluten-free diet for an average of 2.5 years.
Children were evaluated for adherence to their diets using the Biagi gluten-free diet compliance survey, a short list of simple questions on eating habits.
A low score on the Biagi questionnaire strongly agrees with physical and blood tests showing dietary exposure to gluten — in other words, non-adherence.
According to the Biagi analysis, 93.1% of subjects were complying with dietary restrictions.
Investigators collected urine and stool specimens and analyzed them for “gluten immunogenic peptides (GIPs),” gluten breakdown products that the body does not process normally.
GIPs are considered to be the main cause of celiac symptoms and a “direct measure of gluten intake.”
Despite only 6.9% of children reporting poor adherence to gluten-free diets, GIPs at meaningful levels were detected in 20.1% of all children and in 30.6% of males.
This led investigators to conclude that a positive GIP result was not associated with self-reported gluten-free diet adherence or with either blood tests or reported symptoms. Since GIP is present even with adhering to dietary restrictions, GIP testing requires further validation.
