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MRCP PART 1 · CLINICAL IMMUNOLOGY AND ALLERGY

Clinical immunology and allergy questions
for MRCP Part 1.

Clinora has 25 clinical immunology and allergy single best answer questions covering 21 topics. Every question explains all five options, separates the key clue from what it means and what to do next, and links to its source. Try the 5 sample questions below, then practise more for free.

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FREE SAMPLE QUESTIONS

Try 5 clinical immunology and allergy questions

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Question 1Timed tryptase after emergency treatmentHard

A 46-year-old had abrupt hypotension and bronchospasm immediately after an intravenous drug. Intramuscular adrenaline and resuscitation have begun. The team asks when to draw mast-cell tryptase without delaying treatment. Which plan best follows current guidance?

  1. ATake a sample as soon as possible after emergency treatment begins and a second ideally 1–2 hours, no later than 4 hours, from onset
  2. BWait until 24 hours for the only sample
  3. CTake both samples before adrenaline
  4. DSample only after the allergy clinic appointment
  5. EUse a single sample at discharge as definitive proof of cause
Show answer and explanation

Answer: A Take a sample as soon as possible after emergency treatment begins and a second ideally 1–2 hours, no later than 4 hours, from onset

Mast-cell tryptase helps confirm that a reaction was anaphylaxis, but it must never delay treatment. Tryptase peaks around 1–2 hours after onset and falls back over the following day, so timing matters. NICE NG258 recommends the first sample as soon as possible after emergency treatment has started, and a second sample ideally within 1–2 hours, and no later than 4 hours, from the onset of symptoms. A baseline level is then taken later, at follow-up or at least 24 hours after the reaction, so the acute values can be compared with the person's own normal level. A raised acute value against baseline supports mast-cell activation. A normal tryptase does not exclude anaphylaxis, particularly food-triggered reactions, and tryptase does not identify the trigger: that needs specialist allergy assessment.

Key clue
A 46-year-old had abrupt hypotension and bronchospasm immediately after an intravenous drug. Intramuscular adrenaline and resuscitation have begun. The team asks when to draw mast-cell tryptase without delaying treatment. Which plan best follows current guidance?
What it means
NICE recommends two timed acute samples without delaying treatment.
What to do
Take a sample as soon as possible after emergency treatment begins and a second ideally 1–2 hours, no later than 4 hours, from onset

Why the other options are less appropriate

  • B By 24 hours tryptase has usually returned towards baseline, so a single 24-hour sample misses the acute rise. A sample at 24 hours or later serves as the baseline, not the acute measure.
  • C Adrenaline and resuscitation always come first. Delaying them to take blood can be fatal, and very early samples may not yet show the peak.
  • D The allergy clinic visit is the time for the baseline sample, not the acute pair. By then the acute rise is long gone.
  • E One sample at discharge is badly timed, and no tryptase result identifies the cause. It supports mast-cell activation only when compared with baseline.

Source: NICE NG258: timing of blood samples

Question 2Two doses change the observation clockHard

A 28-year-old required two intramuscular adrenaline doses for anaphylaxis after eating at a restaurant. All symptoms have now resolved, and no other high-risk feature is identified. What minimum observation period applies?

  1. AThirty minutes after the first dose
  2. BTwo hours after the first dose
  3. CSix hours after resolution of all symptoms
  4. DTwelve hours in every two-dose case
  5. ENo observation once blood pressure normalises
Show answer and explanation

Answer: C Six hours after resolution of all symptoms

Needing a second adrenaline dose shows a more severe or less responsive reaction, so the risk of a biphasic reaction is higher. NICE NG258 therefore sets a minimum observation period of 6 hours after complete resolution of symptoms when two doses of intramuscular adrenaline were needed, or when there has been a previous biphasic reaction. Observation of at least 12 hours is for higher-risk situations: a severe reaction needing more than two doses, severe asthma or asthma that was part of the reaction, possible continuing absorption of the allergen (for example slow-release medicines), presenting late in the evening, or living where emergency care is hard to reach. The clock always starts from complete resolution, not from when adrenaline was given. Before discharge she should be given two adrenaline auto-injectors with training, written information and an allergy clinic referral.

Key clue
A 28-year-old required two intramuscular adrenaline doses for anaphylaxis after eating at a restaurant. All symptoms have now resolved, and no other high-risk feature is identified. What minimum observation period applies?
What it means
NICE sets a minimum of six hours after complete symptom resolution when two IM doses were needed.
What to do
Six hours after resolution of all symptoms

Why the other options are less appropriate

  • A Thirty minutes is far too short after any anaphylaxis, let alone a reaction that needed two doses.
  • B Two hours applies only when one dose was enough and every other condition is met. The timing also starts from resolution, not from the first dose.
  • D Twelve hours is for the specific higher-risk situations, such as more than two doses or severe asthma, not every two-dose reaction.
  • E A normal blood pressure does not remove the risk of a biphasic reaction. Observation is timed from complete resolution.

Source: NICE NG258: period of observation

Question 3The avoidable-drug exception for injectorsHard

A patient recovered from documented anaphylaxis to an intravenous antibiotic given in hospital. The agent and its class can be reliably avoided; no other anaphylaxis risk is known. What does current NICE guidance say about discharge auto-injectors?

  1. ATwo auto-injectors are the default, but an exception applies when a drug trigger can be reliably avoided
  2. BPrescribe two auto-injectors after every anaphylaxis, whatever the cause
  3. CAn injector is never considered after drug-related anaphylaxis
  4. DA normal tryptase alone determines the prescription
  5. EPrescribe one auto-injector, because a single dose treats most reactions
Show answer and explanation

Answer: A Two auto-injectors are the default, but an exception applies when a drug trigger can be reliably avoided

Adrenaline auto-injectors are prescribed so that a patient can treat a future, unpredictable episode before help arrives. When anaphylaxis was caused by a drug given in hospital, and that drug and its class can be reliably avoided, the risk of an unplanned reaction in the community is very low, so an auto-injector is not routinely needed. Where an injector is indicated, UK practice is to prescribe two and to make sure they are in date, because one dose may not be enough and devices can fail. MHRA advice supports carrying two at all times. Before discharge, everyone should have the drug allergy clearly recorded in the medical record and on any alert systems, be told the name of the drug and related agents to avoid, and be referred to a specialist allergy service. Mast cell tryptase should be timed, with a sample taken as soon as possible after emergency treatment starts and a second ideally within 1–2 hours, and no later than 4 hours, of the start of symptoms. A normal tryptase does not rule out anaphylaxis. A cause that cannot be avoided, such as food, venom or idiopathic anaphylaxis, still needs injectors and training.

Key clue
A patient recovered from documented anaphylaxis to an intravenous antibiotic given in hospital. The agent and its class can be reliably avoided; no other anaphylaxis risk is known. What does current NICE guidance say about discharge auto-injectors?
What it means
NICE normally ensures two in-date injectors at discharge but explicitly exempts an easily avoidable drug-allergy cause.
What to do
Two auto-injectors are the default, but an exception applies when a drug trigger can be reliably avoided

Why the other options are less appropriate

  • B Two injectors are the default, but a drug trigger that can be reliably avoided is a recognised exception, so they are not needed for every cause.
  • C The exception applies only when the drug can be reliably avoided. If avoidance is uncertain, or other risks exist, an injector should still be considered.
  • D Tryptase helps to confirm the diagnosis but cannot exclude anaphylaxis. It does not decide whether an injector is needed.
  • E Where an injector is indicated, two are prescribed, because a second dose may be needed and devices can fail.

Source: NICE NG258: discharge

Question 4Non-specialist serum IgE testingHard

A 32-year-old reports previous throat tightness and hives after amoxicillin. A general medical clinic proposes a serum-specific IgE panel as the sole method to confirm or exclude drug allergy. What is the best response?

  1. ATreat a negative IgE result as permission for an unsupervised full-dose challenge
  2. BTest total IgE instead and remove the label
  3. CGive amoxicillin at home to confirm the story
  4. DDo not use serum-specific IgE to diagnose drug allergy in a non-specialist setting; assess and refer appropriately
  5. EAssume every beta-lactam is safe because the event was remote
Show answer and explanation

Answer: D Do not use serum-specific IgE to diagnose drug allergy in a non-specialist setting; assess and refer appropriately

Throat tightness and hives after amoxicillin suggest an immediate, IgE-mediated reaction. Serum-specific IgE testing for drug allergy has limited sensitivity, so a negative result cannot exclude allergy, and a positive result can be misinterpreted without the clinical history. NICE CG183 advises against using serum-specific IgE testing to diagnose drug allergy in non-specialist settings. The correct response is a clear clinical assessment: document the drug, the timing, the features of the reaction and the treatment needed, and refer to a specialist drug allergy service where appropriate. CG183 advises referral after a suspected anaphylactic reaction or severe non-immediate cutaneous reaction, and for people with a suspected beta-lactam allergy who need, or are likely to need, beta-lactam treatment. Specialist services use structured risk assessment, skin testing and supervised drug challenge, and many penicillin allergy labels are removed this way. Until then, avoid penicillins. Cephalosporins can often be used with specialist advice, depending on the reaction.

Key clue
A 32-year-old reports previous throat tightness and hives after amoxicillin. A general medical clinic proposes a serum-specific IgE panel as the sole method to confirm or exclude drug allergy. What is the best response?
What it means
NICE explicitly advises against non-specialist serum-specific IgE testing to diagnose drug allergy.
What to do
Do not use serum-specific IgE to diagnose drug allergy in a non-specialist setting; assess and refer appropriately

Why the other options are less appropriate

  • A A negative specific IgE does not exclude allergy. An unsupervised full-dose challenge risks a serious, possibly anaphylactic, reaction.
  • B Total IgE reflects general atopy and says nothing about allergy to a specific drug, so it cannot justify removing the label.
  • C Giving amoxicillin at home re-exposes her to a drug that caused throat tightness, without monitoring or treatment available.
  • E Allergy can persist for years. Time alone does not make penicillins safe, and cross-reactivity must be judged by a specialist.

Source: NICE CG183

Question 5Recurrent need for beta-lactamsHard

A 58-year-old with bronchiectasis has frequent bacterial infections and a childhood penicillin-allergy label of uncertain features. Repeated courses of less suitable broad-spectrum alternatives have been required. What is the best longer-term approach?

  1. APreserve the label without review indefinitely
  2. BRefer to a specialist drug-allergy service because beta-lactams are likely to be needed frequently
  3. CRemove the label solely because many years have passed
  4. DPerform an unsupervised oral challenge at home
  5. EPrescribe empiric corticosteroids before every antibiotic course
Show answer and explanation

Answer: B Refer to a specialist drug-allergy service because beta-lactams are likely to be needed frequently

Most penicillin-allergy labels are inaccurate. Many come from childhood rashes during viral infections, and a label of uncertain features often does not reflect true allergy. Carrying the label leads to broader-spectrum alternatives, which work less well and carry a higher risk of MRSA, Clostridioides difficile and antimicrobial resistance. In bronchiectasis this matters a great deal, because beta-lactams are often needed for repeated exacerbations. NICE CG183 recommends referral to a specialist drug allergy service for people with suspected beta-lactam allergy who are likely to need beta-lactams often in the future, for example because of recurrent bacterial infection or immune deficiency. Referral is also recommended when a condition can only be treated with a beta-lactam. The service takes a structured history, then may do skin testing and a supervised oral challenge, which is the reference standard. If the label is removed, the record must be updated clearly. Until then, NICE asks for the drug, the reaction and the date to be documented in all records.

Key clue
A 58-year-old with bronchiectasis has frequent bacterial infections and a childhood penicillin-allergy label of uncertain features. Repeated courses of less suitable broad-spectrum alternatives have been required. What is the best longer-term approach?
What it means
NICE recommends specialist referral when suspected beta-lactam allergy limits treatment likely to be needed repeatedly.
What to do
Refer to a specialist drug-allergy service because beta-lactams are likely to be needed frequently

Why the other options are less appropriate

  • A Keeping an unreviewed label means repeated use of less suitable antibiotics and avoidable harm from resistance and C. difficile.
  • C Time alone does not prove tolerance. The label should be removed only after proper assessment or a supervised challenge.
  • D An unsupervised challenge at home risks an untreated reaction. Challenges should be done where anaphylaxis can be managed.
  • E Steroid premedication does not prevent IgE-mediated anaphylaxis reliably and does not show whether the patient is allergic.

Source: NICE CG183

That is 5 of 25. Carry on with clinical immunology and allergy in the practice bank, with progress tracking, flashcards and timed sessions.

Practise clinical immunology and allergy free →

Topics covered

Show all 21 clinical immunology and allergy topics
  • Allergy referral after a suspected episode
  • Fever, eosinophilia and liver injury weeks later
  • Hereditary angioedema
  • Immunodeficiency assessment without PPV23
  • Immunoglobulin replacement after anti-CD20 therapy
  • Immunoglobulin replacement without a PPV23 response
  • Isolated gastrointestinal symptoms and a drug label
  • Local anaesthetic allergy threatens a necessary procedure
  • Low IgG with preserved vaccine responses
  • Non-specialist serum IgE testing
  • Persistent infections despite immunoglobulin replacement
  • Rapid discharge is conditional
  • Recording a newly suspected reaction
  • Recurrent need for beta-lactams
  • Severe asthma after anaphylaxis
  • Severe NSAID reaction and COX-2 treatment
  • Specific antibody deficiency with normal total IgG
  • The avoidable-drug exception for injectors
  • Timed tryptase after emergency treatment
  • Two doses change the observation clock
  • Very low IgG in primary immunodeficiency

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