Chapter 28 — Self-Check Quiz

20 questions. Answers with explanations at the end. Aim for 16+.

Questions

1. Which two mechanisms are the ones where very small amounts matter?

• a) Lactose intolerance and FODMAP sensitivity
• b) IgE-mediated allergy and coeliac disease
• c) Histamine intolerance and nocebo
• d) Pharmacological and enzymatic

2. "It's nocebo" means:

• a) The person is making it up
• b) The symptoms are genuinely experienced but the trigger isn't the food
• c) There are no symptoms
• d) The food is safe for everyone

3. Which allergies usually persist rather than being outgrown?

• a) Milk, egg, wheat, soy
• b) Peanut, tree nuts, fish, shellfish
• c) All are outgrown
• d) None are outgrown

4. First-line treatment for anaphylaxis is:

• a) An oral antihistamine
• b) Intramuscular adrenaline into the anterolateral thigh
• c) An inhaler
• d) Oral corticosteroids

5. Antihistamines in anaphylaxis:

• a) Reverse airway compromise
• b) May help itching and urticaria but do not treat anaphylaxis — reaching for one instead of adrenaline is the most common fatal error
• c) Are the preferred first-line agent
• d) Raise blood pressure

6. Regarding skin signs in anaphylaxis:

• a) They are always present
• b) A substantial minority of fatal cases had no rash — waiting for hives is waiting for something that may not come
• c) They are the only diagnostic criterion
• d) They appear before any other sign

7. Which is a recognized cofactor that can convert a tolerated exposure into anaphylaxis?

• a) Exercise
• b) Alcohol
• c) NSAIDs
• d) All of the above

8. Skin prick tests and specific IgE blood tests measure:

• a) Allergy
• b) Sensitization — the presence of specific IgE, which does not mean you will react
• c) Intolerance
• d) Enzyme activity

9. The gold standard for diagnosing food allergy is:

• a) A large IgE panel
• b) Oral food challenge
• c) Hair analysis
• d) Skin prick testing

10. Coeliac disease is:

• a) An allergy
• b) An autoimmune disease triggered by gluten in genetically susceptible people
• c) An enzyme deficiency
• d) A FODMAP intolerance

11. Which should prompt coeliac screening?

• a) Unexplained iron-deficiency anaemia
• b) Only classic diarrhoea and weight loss
• c) A positive IgG panel
• d) Bloating alone

12. Coeliac testing requires that you:

• a) Have been gluten-free for a month
• b) Are currently eating gluten — both serology and biopsy normalize on a gluten-free diet
• c) Fast for 24 hours
• d) Take a lactase supplement

13. Gluten-free replacement products are typically:

• a) Nutritionally identical to conventional versions
• b) Lower in fibre, iron and B vitamins, higher in fat and sugar, and several times the price
• c) Higher in fibre
• d) Cheaper

14. Lactase non-persistence affects approximately what share of the world's adults?

• a) Under 5%
• b) Roughly two-thirds
• c) Exactly half
• d) Over 95%

15. Lactose intolerance is best managed by:

• a) Complete lifelong dairy elimination
• b) Finding the threshold — most tolerate around a cup of milk's worth, especially with food; yoghurt and hard cheese are usually fine
• c) An IgG panel
• d) Adrenaline

16. The Skodje et al. crossover study in self-reported gluten sensitivity found that symptoms were provoked by:

• a) Gluten
• b) Fructan — the FODMAP in wheat — and not gluten
• c) Neither, in anyone
• d) Placebo only

17. IgG food antibody panels measure:

• a) Allergy
• b) Exposure — and possibly tolerance; the test reliably identifies what you eat
• c) Enzyme deficiency
• d) Intestinal permeability

18. Oral allergy syndrome is usually tolerable in cooked form because:

• a) Cooking removes the allergen entirely
• b) The cross-reacting proteins are heat-labile
• c) Cooking adds enzymes
• d) It doesn't — cooked forms are worse

19. Oral immunotherapy achieves:

• a) Cure
• b) Desensitization — a raised threshold while treatment continues, lost if dosing stops
• c) Permanent tolerance after one course
• d) Nothing measurable

20. §28.14b's "uncomfortable row" is that:

• a) Vitamin D was overrated
• b) Decades of guidance advised delaying allergenic foods, was followed conscientiously, and probably caused harm while it stood
• c) The hygiene hypothesis was fabricated
• d) Allergy prevalence has not actually risen

Answers

1. b) IgE allergy and coeliac disease. ⚠️ Almost everything else is a threshold effect — which is why the question is usually "how much," not "never," and why person 3 at the dinner table can eat yoghurt while person 2 cannot have a crumb. §28.1.

2. b) Genuinely experienced, but the trigger isn't the food. ⚠️ In blinded challenges a substantial proportion of people who reliably report symptoms develop them on placebo — through real physiological pathways. Saying "it's nocebo" is not saying "you're making it up." §28.1.

3. b) Peanut, tree nuts, fish, shellfish. ⚠️ Milk, egg, wheat and soy allergies are often outgrown, which means a child should be REASSESSED periodically rather than avoiding indefinitely by default. §28.2.

4. b) Intramuscular adrenaline, anterolateral thigh. ⚠️ No absolute contraindication. Delay is associated with death. If you're unsure whether it's anaphylaxis, give it. §28.3.

5. b) They don't treat it. ⚠️ The most common fatal error. They may help urticaria and itching; they do not reverse airway compromise or hypotension. §28.3.

6. b) A substantial minority of fatal cases had no rash. ⚠️ The rule that removes hesitation: airway, breathing or circulation involvement — or two or more systems — after a likely exposure. Give adrenaline. §28.3.

7. d) All of the above. ⚠️ Plus infection and menstruation. A food tolerated last week can produce anaphylaxis after a run or a drink — food-dependent exercise-induced anaphylaxis is a recognized entity, most classically with wheat. §28.3.

8. b) Sensitization. ⚠️ Many people are sensitized to foods they eat without any problem. Which produces the rule: the history drives the testing; the testing does not drive the diagnosis. §28.4.

9. b) Oral food challenge. Supervised. §28.4.

10. b) Autoimmune. ⚠️ Not an allergy, not an intolerance — an immune attack on your own tissue, in people carrying HLA-DQ2 or DQ8, prevalence around 1% and largely undiagnosed. §28.5.

11. a) Unexplained iron-deficiency anaemia. ⚠️ The presentation is frequently NOT gastrointestinal — anaemia, fatigue, osteoporosis, raised liver enzymes, dermatitis herpetiformis, infertility, neurological symptoms. One of the highest-yield tests in general practice, frequently not done. §28.5.

12. b) Currently eating gluten. ⚠️ Remove it first and serology and biopsy both normalize — and the only way back is a deliberate weeks-long gluten challenge that many refuse, leaving them on a lifelong restriction with no diagnosis, no follow-up, no bone monitoring, and no answer for relatives who should be screened. The most actionable instruction in the chapter and the one most often reversed. §28.6.

13. b) Lower in fibre, iron and B vitamins; higher in fat and sugar; several times the price. ⚠️ Because fortification of wheat flour doesn't apply to them. The commonest post-diagnosis error is replacing every wheat product with a packaged gluten-free version — the better move is rice, potatoes, buckwheat, quinoa, certified oats, beans and lentils. §28.6.

14. b) Roughly two-thirds. ⚠️ Lactase PERSISTENCE is the derived, unusual trait. All mammals lose lactase after weaning; keeping it is the exception, and it varies enormously by ancestry. Lactose intolerance is normal adult human physiology, not a disease. §28.7.

15. b) Find the threshold. ⚠️ Most tolerate around 12 g — a cup of milk — especially with food and spread through the day. Hard cheese contains very little lactose; yoghurt contains bacterial lactase. ⚠️ Don't eliminate entirely — calcium, and Chapter 25's sixty-year bone story. (Also: post-gastroenteritis lactose intolerance is temporary and resolves.) §28.7.

16. b) Fructan, not gluten. ⚠️ Which points at the FODMAP in wheat, and means removing gluten removes wheat which removes fructans — Chapter 17's bundled intervention. Both halves of §28.8 stand: something real is happening in at least some people, and gluten is probably not the agent in most. §28.8.

17. b) Exposure. ⚠️ IgG to food is a normal, expected marker of exposure and possibly of tolerance. The test reliably identifies what you eat. Major allergy and immunology bodies have issued explicit statements against its use for this purpose. §28.10.

18. b) The cross-reacting proteins are heat-labile. ⚠️ Someone who reacts to a raw apple can usually eat apple pie. Common, reassuring once explained — and worth assessing rather than dismissing, since it occasionally progresses. §28.9.

19. b) Desensitization. ⚠️ The threshold rises while treatment continues; it is not a cure, it requires ongoing daily dosing, and protection is lost if dosing stops. You still avoid the food, still carry adrenaline, still read labels. ⚠️ And some analyses find OIT increases anaphylaxis DURING the treatment period compared with avoidance — a genuine trade-off that should be discussed explicitly. §28.13.

20. b) Delayed-introduction guidance. ⚠️ Reasonable given what was known, followed conscientiously, and probably counterproductive. Chapter 17's stale-guidance category — and a reminder that stale guidance is not merely a failure to update: sometimes the advice actively caused harm while it stood. Which is an argument for humility about current recommendations, including this chapter's. §28.14b.

Scoring

Four items worth checking regardless of score — and this is the only chapter where I'd say a wrong answer could matter within the hour.

Questions 4, 5 and 6. ⚠️ If you got any of these wrong and you are ever near someone with an allergy, reread §28.3 now. Hesitation is the failure mode, and it comes from exactly these uncertainties.

Question 12. ⚠️ The most actionable instruction in the chapter, and the one people most often reverse.