A result is not only a number or a name. It is an observation produced from a particular specimen, by a particular method, at a particular point in the patient's story.
This mixed pathology quiz asks what the finding supports, how it connects with the underlying process and what information is still missing. There are ten original questions, a separate answer key and a five-question version for a shorter teaching session.
National Pathology Week 2026 runs from 2 to 8 November, according to the Royal College of Pathologists. This independently produced iatroX quiz can be used around that occasion or at any other time. It is not an official campaign resource or endorsed examination.
The clinical examples are fictional. Laboratory ranges and numerical test-performance assumptions are stated where relevant; real decisions require the complete clinical assessment and the laboratory's actual methods.
How to use the quiz
Answer the questions before revealing the key. Give one point for the principal answer and another for explaining the relevant distinction, producing an informal total out of twenty.
For a group, allow an individual attempt before discussion. A correct answer offered by the most vocal participant does not show what everyone else understood.
The score is simply an organising device. It is not a validated assessment of pathology knowledge or clinical competence.
The ten questions
1. The potassium and the specimen
A clinically stable adult has potassium reported as 6.2 mmol/L, against a laboratory interval of 3.5-5.3 mmol/L. The report also identifies significant sample haemolysis. Previous renal function and potassium were unremarkable.
Question: how could haemolysis outside the body affect the potassium measurement? Does the sample warning justify either automatically treating the number as exact or dismissing the result without prompt clinical review and a reliable measurement?
2. Troponin identifies an injury, but not every cause
An acutely unwell patient has cardiac troponin above the assay's 99th-percentile upper reference limit. No previous value, serial change, ECG interpretation or adequate symptom assessment has yet been supplied.
Question: what broad finding is established, assuming the measurement is valid? What additional relationship is needed before calling the presentation an acute myocardial infarction?
3. Two routes to a positive surface antibody
Interpret these two hepatitis B panels. Assume accurate testing and no recent passive antibody administration. Person A has a documented completed vaccination course.
| Marker | Person A | Person B |
|---|---|---|
| HBsAg | Negative | Negative |
| Total anti-HBc | Negative | Positive |
| Anti-HBs | Positive | Positive |
Question: which pattern is consistent with vaccine-derived immunity, and which with resolved infection? Which marker supplies the key distinction?
4. A high-grade tumour is not automatically an advanced-stage tumour
A biopsy describes a high-grade malignancy. The report does not state the anatomical extent of disease, and staging investigations have not yet been completed.
Question: what does grade describe? What different question does stage address, and why can the biopsy adjective not answer both?
5. Amyloid has been found, but the protein has not been typed
A tissue biopsy identifies amyloid deposits. The report explicitly states that the amyloid protein has not yet been characterised. A reader proposes that the word "amyloid" alone establishes AL amyloidosis and its treatment.
Question: what is missing from that conclusion? Why does identifying the type matter after the deposit has been recognised?
6. A test taken before its answer is available
A patient has a negative laboratory HIV antigen/antibody test twelve days after a potential exposure. There has been no later test. The question supplies no basis for assuming that all relevant infection markers must already be detectable.
Question: why is this result insufficient to exclude infection from that exposure? What two pieces of information determine the interpretation of a negative test in relation to a window period?
7. A prolonged APTT changes after mixing
A laboratory investigates an isolated prolonged APTT. In a simplified example, mixing the patient's plasma with normal pooled plasma produces correction that persists under the laboratory's immediate and incubated assessment. No relevant anticoagulant interference is identified.
Question: does this pattern favour a factor deficiency or an inhibitor? Would failure to correct establish one particular inhibitor without further investigation?
8. A tumour variant is not automatically an inherited variant
Tumour sequencing identifies a pathogenic variant that can also be associated with an inherited cancer-predisposition syndrome. No suitable non-tumour sample has been tested.
Question: does the tumour result alone establish that the variant is present in the germline? What distinction should the clinician explain before drawing conclusions about relatives?
9. The apparently accurate test in a low-prevalence population
This is an arithmetic exercise, not a description of a commercial test.
A hypothetical test has 90% sensitivity and 90% specificity in the population under consideration. Exactly 10 of 1,000 people have the condition, representing 1% prevalence. Assume those performance values apply and that the resulting numbers follow the stated proportions exactly.
Question: how many true positives and false positives are expected? Of everyone testing positive, what proportion actually has the condition?
Optional change: hold sensitivity and specificity constant but increase prevalence to 20%. What happens to the positive predictive value?
10. HbA1c after the red-cell population changes
A patient with diabetes has recently received a red-cell transfusion after significant blood loss. HbA1c is now 44 mmol/mol, while several recent capillary glucose measurements are between 12 and 17 mmol/L.
Question: why should the HbA1c not automatically be interpreted as proof of a sustained improvement in glycaemia? Which aspect of the measurement's biological basis has changed?
A five-question version for a short session
For a smaller discussion, use questions 2, 3, 4, 8 and 9. This keeps a mixture of biochemistry, virology, histopathology, molecular interpretation and test statistics.
A suggested fifteen-minute structure is five minutes for individual answers, seven minutes for discussion and three minutes to identify one point worth revisiting. These are planning suggestions, not measured completion times.
Use the same two-point scheme, giving a total out of ten for the short version. Keep the answer key below hidden until participants have committed to their initial interpretations.
Answer key and explanations
1. In-vitro haemolysis can increase the measured potassium
Potassium released from damaged cells can raise the concentration measured in the specimen without establishing an equivalent change in the patient's circulating potassium.
The UK Kidney Association's hyperkalaemia guideline discusses haemolysis, sample quality and the need for timely, accurate measurements.
The response is prompt clinical assessment and reliable verification, not automatic acceptance or dismissal. A sample problem does not guarantee that true hyperkalaemia is absent. Urgent treatment must not be delayed when the clinical and electrocardiographic situation requires it.
This is a pre-analytical question: what happened to the specimen can affect what the result appears to say about the patient.
The clinical connections game provides another opportunity to identify a meaningful relationship rather than stopping at a familiar term.
2. Myocardial injury is not synonymous with myocardial infarction
A valid elevated troponin establishes myocardial injury. Acute infarction additionally requires the relevant acute biomarker pattern and evidence of myocardial ischaemia, interpreted in the clinical setting.
The MSD Manual's myocardial-infarction account explains the relationship between biomarkers, symptoms, ECG findings and imaging.
The question deliberately withholds information needed to complete that interpretation. Neither an automatic infarction label nor dismissal as an incidental result is justified.
The distinction should not delay emergency care when the presentation already warrants it. It prevents a biomarker from being treated as a complete account of the mechanism.
3. A fits vaccination; B fits resolved infection
Person A's surface antibody without core antibody is consistent with the documented vaccination history. Person B's combination of surface and core antibodies, with negative surface antigen, is consistent with resolved infection.
The CDC's hepatitis B interpretation guide distinguishes these patterns. Vaccination does not generate anti-HBc, making the core antibody the decisive difference in this exercise.
A positive surface antibody is therefore not, on its own, a complete history of how immunity developed. The broader panel supplies information that the individual result cannot.
This question concerns marker interpretation, not an instruction to apply US population-screening recommendations to every UK clinical setting.
4. Grade concerns appearance; stage concerns extent
Grade describes features of the tumour cells and tissue under the microscope, including how abnormal or differentiated they appear within the relevant grading system. Stage describes the extent of disease, using the system appropriate to that malignancy.
The National Cancer Institute's grade explanation separates these concepts.
A high-grade tumour may be detected before extensive spread, while another tumour can be anatomically advanced without receiving the same grade. The measurements answer different questions.
Do not infer a complete prognosis or treatment choice from either label alone. Tumour type and additional clinical and molecular information can also matter.
5. Recognising amyloid does not identify every amyloid protein
The deposit has been recognised, but its type remains unresolved. The label alone does not establish that the deposited material is immunoglobulin light chain or that an AL-specific treatment pathway applies.
Mayo Clinic's amyloidosis diagnostic guidance emphasises accurate typing because management differs substantially between forms.
The pathology and clinical teams need an appropriate characterisation process and assessment of organ involvement. Finding an associated abnormality elsewhere should not silently substitute for identifying the deposited material.
The question illustrates a common diagnostic distinction: recognising a pathological process and establishing its cause are separate achievements.
6. Timing and test type determine the relevant window
No HIV test detects infection immediately after acquisition. Different assays become informative over different intervals.
The CDC's HIV testing guidance describes a typical detection window of 18-45 days for a laboratory antigen/antibody test on venous blood. Twelve days is therefore too early to use the supplied negative result as an exclusion.
The essential information is the time since the relevant exposure and the exact test used. Prevention medicines and other clinical circumstances can also affect the testing plan.
Follow-up should use the appropriate clinical pathway. Time-sensitive exposure management is a separate question and should not be deferred while waiting for a later test.
7. Persistent correction supports a factor-deficiency pattern
Normal pooled plasma can supply a deficient factor. Correction therefore favours a deficiency in the simplified circumstances described, although it does not identify which factor is affected.
ARUP Consult's haemophilia testing guidance explains the distinction from an inhibitor pattern and the importance of incubation for some time-dependent inhibitors.
Failure to correct has several possible explanations, including particular factor inhibitors, lupus anticoagulant and interfering anticoagulant medicines. It does not name one of those by itself.
The laboratory's method and interpretation matter. The exercise is about what the change suggests, not permission to disregard sample quality or bypass subsequent testing.
8. A tumour-only finding does not establish germline status
A genetic change identified in tumour tissue may be acquired within the tumour or may also be inherited. The tumour result alone does not establish which explanation applies.
The National Cancer Institute's biomarker-testing guide distinguishes tumour testing from tests used to confirm an inherited predisposition.
Appropriate genetics assessment and confirmatory testing may be needed before advising relatives on a presumed familial variant.
The clinician should preserve both possibilities: the result may be important for the family, but that importance must be investigated rather than announced as already established.
9. Nine true positives and ninety-nine false positives
Of ten people with the condition, 90% test positive: 9 true positives. Of 990 without it, 10% test positive: 99 false positives.
There are therefore 108 positive results, of which nine identify the condition correctly:
Positive predictive value = 9 / (9 + 99) = 8.3%, approximately.
The result is an original calculation using the hypothetical assumptions, not observed performance data.
At 20% prevalence in the same thousand-person example, there would be 180 true positives and 80 false positives. The positive predictive value becomes 180 / 260 = 69.2%, approximately.
Changing the proportion with the condition changes the composition of positive results, even when sensitivity and specificity are held constant. A test's headline percentages do not replace the clinical question of whom it is being used to assess.
10. The red-cell history affects what HbA1c represents
HbA1c depends on haemoglobin within circulating red cells. Recent blood loss and transfusion change the population being measured, making a simple interpretation as the patient's preceding average glycaemia unreliable.
The NIDDK's HbA1c guidance describes red-cell conditions and transfusion among factors that can alter the result.
The discordant glucose measurements need clinical assessment rather than being dismissed because the HbA1c appears lower. At the same time, a few capillary measurements do not reconstruct every preceding day.
The next interpretation should use the clinical history and suitable current glycaemic information, not assume that either measurement answers every question.
Organiser's compact answer sheet
| Question | Principal answer | Distinction to hear in the explanation |
|---|---|---|
| 1 | Sample haemolysis can raise measured potassium | Specimen effect versus actual circulating concentration |
| 2 | Myocardial injury is established | Infarction additionally needs an ischaemic clinical relationship |
| 3 | A: vaccination; B: resolved infection | Core antibody distinguishes the supplied patterns |
| 4 | Grade and stage are different | Microscopic character versus anatomical extent |
| 5 | Amyloid typing remains necessary | Finding a deposit versus identifying its protein |
| 6 | The negative result is too early to exclude the exposure | Test type and time determine the window |
| 7 | Correction favours a factor deficiency | A pattern is not a specific factor diagnosis |
| 8 | Germline status is not established | Tumour-only finding versus inherited variant |
| 9 | PPV approximately 8.3% | True positives must be compared with all positives |
| 10 | HbA1c interpretation is affected | The red-cell population has changed |
The sheet is for marking and discussion. The explanations above retain the qualifications that a compact answer cannot carry by itself.
End with one better laboratory question
Ask each participant to complete this sentence: "Before accepting the interpretation, I would need to know..."
Their answer might concern timing, specimen quality, the exact population counted, a previous result or whether the test measured the thing they assumed it measured.
That is a useful endpoint for a short session. It turns a collection of facts into a question that can be applied to a different result.
For independent practice afterwards, clinical connections offers a mixed clinical-science puzzle with explanations. stat offers three separate UK-context decisions. Neither game is guaranteed to contain a pathology edition today, and facilitated group play should not be presented as evidence of each participant's independent performance.
Frequently asked questions
Is this an official National Pathology Week quiz?
No. It is an independently produced iatroX article. The campaign dates are linked to the Royal College of Pathologists, but no endorsement is claimed.
Can I use a shorter version in a clinical meeting?
Yes. Questions 2, 3, 4, 8 and 9 provide the suggested five-question version, with the same separated explanations and a total out of ten.
Does completing the quiz automatically award CPD credits?
No. Completing a quiz, undertaking relevant learning and meeting any professional accreditation requirements are different things. The score is an informal discussion aid.
Explore another set of clinical-science relationships in today's clinical connections puzzle