Sensitosis archive
Every past round of real medical tests, with their sensitivity, specificity and sources. Newest first.
4 past puzzles, up to Thursday 5 November 2026. Today’s and future puzzles are never shown here.
November 2026
#4 · Thursday 5 November 2026 Medium
Phalen’s test for carpal tunnel syndrome
Numb, tingly fingers that wake you at night. You press the backs of your hands together, wrists bent, for a minute. Tingling in the fingers is positive.
Sensitivity 68% (range 57%–69%); specificity 73% (range 67%–73%).
Middling both ways. A third of people with carpal tunnel pass it, and plenty without it fail. Nerve conduction studies are the usual tiebreaker.
A meta-analysis cited in J Fam Pract 2012 found 68 and 73; later meta-analyses landed nearby (57 to 69 caught, 67 to 71 cleared).
Source: Wipperman and Potter 2012, Carpal tunnel syndrome: try these diagnostic maneuvers (J Fam Pract); LITFL: Phalen test (summary of reviews)
Rapid flu test (adults) for the flu
Fever, aches, the works. A quick nose swab for influenza at the clinic.
Sensitivity 54% (range 48%–60%); specificity 98% (range 97%–99%).
A coin toss for catching flu in adults, but a positive is very believable. Good for ruling in, bad for ruling out.
Rapid antigen tests, meta-analysis 2012. Specificity was reported for all ages combined.
Source: Chartrand 2012 meta-analysis (Ann Intern Med), summarised by ACP
BNP blood test (above 100 ng/L counts as high) for Heart failure as the cause of sudden breathlessness
Suddenly short of breath and puffy ankles. The emergency doctor orders a blood test.
Sensitivity 95% (range 92%–98%); specificity 63% (range 52%–73%).
A normal result makes heart failure quite unlikely. A high one is more of a shrug, because plenty of other things can push BNP up too.
Pooled from 19 study groups, about 6,950 adults, mainly in emergency departments.
Source: Roberts et al, BMJ 2015: natriuretic peptides in acute heart failure (open-access PDF)
Tinel’s sign for carpal tunnel syndrome
Same tingly fingers. The doctor taps over the front of your wrist. A zing shooting into the fingers is positive.
Sensitivity 50% (range 50%–50%); specificity 77% (range 77%–77%).
Tap, tap, coin toss. It catches half of cases. A JAMA review lumped Tinel’s and Phalen’s in with the least useful signs.
Figures from the table in a 2012 J Fam Pract review. The JAMA Rational Clinical Examination review (D’Arcy and McGee 2000) rated both as having little or no diagnostic value.
Source: Wipperman and Potter 2012, Carpal tunnel syndrome: try these diagnostic maneuvers (J Fam Pract); Epistemonikos: D’Arcy and McGee 2000 (JAMA) abstract
Faecal calprotectin (adults) for inflammatory bowel disease (Crohn’s or colitis)
Months of tummy pain and loose poo. IBS, or inflamed bowel? A poo test for calprotectin.
Sensitivity 93% (range 85%–97%); specificity 96% (range 79%–99%).
One of the good ones in adults. Negative? Inflamed bowel is unlikely, and you may skip a colonoscopy.
Twist: In the BMJ review’s example, about 1 in 3 adults sent for this test had bowel disease.
Meta-analysis of 6 adult studies (2010). Specificity varied a lot between studies.
#3 · Wednesday 4 November 2026 Medium
Ferritin (under 30 counts as low) for iron deficiency
Tired all the time. Your GP checks ferritin, your iron stores. Under 30 counts as positive.
Sensitivity 92% (range 82%–100%); specificity 85% (range 75%–92%).
A cut-off of 30 catches most iron deficiency. The catch: inflammation pushes ferritin up, so it can look normal when it isn’t.
Small studies that varied a lot. Experts say better studies are urgently needed.
Source: Daru 2017 review: Serum ferritin as an indicator of iron status (Am J Clin Nutr)
Murphy’s sign for an inflamed gallbladder (cholecystitis)
Pain under the right ribs after a fatty meal. The doctor presses there and asks you to breathe in. If you stop mid-breath in pain, that’s positive.
Sensitivity 65% (range 58%–71%); specificity 87% (range 85%–89%).
Better at ruling in than out: it misses about 1 in 3. Hence the ultrasound.
Pooled figures from the Trowbridge 2003 JAMA review. Single studies varied a lot: 44 to 97 caught, 48 to 96 cleared.
Source: Trowbridge 2003 JAMA review, teaching summary (University of Florida); EBM Consult: Murphy’s sign
Urine dipstick: nitrite for a UTI
Burning when you wee. The GP dips a strip in your urine. Positive here means the nitrite pad changes colour.
Sensitivity 53% (range 44%–65%); specificity 88% (range 81%–96%).
Nitrite positive is a decent clue. Nitrite negative? Means little: about half of UTIs don’t show it.
Twist: Imagine a clinic where half the people with burning wees have a UTI.
Pooled from 6 general practice studies (2004 meta-analysis).
Source: Devillé 2004 meta-analysis: the urine dipstick test (BMC Urology)
Straight leg raise for sciatica from a slipped disc
Back pain shooting down one leg. You lie flat and the doctor slowly lifts your straight leg. If that brings on the pain down your leg, it’s positive.
Sensitivity 92% (range 87%–95%); specificity 28% (range 18%–40%).
Brilliant at catching it, hopeless at clearing it: lots of people without a slipped disc get leg pain too. A negative test is the useful one. Lifting the other leg flips it: 28 caught, 90 cleared.
Cochrane 2010, mostly in people having surgery, so general practice may differ. Specificity ranged from 10 to 100 across studies.
Source: Cochrane review: physical examination for lumbar radiculopathy (2010)
Urea breath test for H. pylori (the stomach ulcer bug)
Burning tummy. You drink a special drink, then blow into a bag.
Sensitivity 94% (range 89%–97%); specificity 90% (range 89%–91%).
The best non-invasive test for H. pylori. Stop acid tablets and antibiotics beforehand or you’ll fool it.
The Cochrane review compared tests at a fixed specificity of about 90%, so that figure is set, not measured.
Source: Cochrane review: non-invasive tests for H. pylori (2018)
#2 · Tuesday 3 November 2026 Easy
Urine dipstick: nitrite or white cells for a UTI
Same strip, but now either pad (nitrite or white cells) changing colour counts as positive.
Sensitivity 90% (range 89%–92%); specificity 65% (range 61%–69%).
Count either pad and you catch most UTIs, but you also get lots of false alarms. Symptoms still matter most.
General practice estimate rests on only 2 studies; treat as rough.
Source: Devillé 2004 meta-analysis: the urine dipstick test (BMC Urology)
Thompson’s (Simmonds’) test for a torn Achilles tendon
A loud snap at the back of your ankle during touch footy. You kneel on a chair and the doctor squeezes your calf. If your foot doesn’t point down, that’s positive.
Sensitivity 96% (range 96%–96%); specificity 93% (range 93%–93%).
A ten-second squeeze that almost never gets it wrong. Rare for a bedside test.
Reiman 2014 meta-analysis (J Athl Train), as reported by Physiotutors; FPnotebook gives the same figures.
Source: Physiotutors: Thompson test; FPnotebook: Thompson’s test
COVID RAT with no symptoms for COVID
You feel perfectly fine. You swab before visiting your nan, just in case.
Sensitivity 55% (range 48%–62%); specificity 99.7% (range 99%–100%).
Without symptoms, a RAT catches only about half of infections. A negative is reassuring-ish, not a free pass. A positive, though? Believe it.
Same Cochrane review. Fewer studies in people without symptoms (50 evaluations).
Source: Cochrane review (Dinnes 2022), summarised in American Family Physician 2023
Monospot test for glandular fever
A teen with a wrecked throat, swollen glands and exhaustion. Quick blood test for glandular fever.
Sensitivity 87% (range 84%–90%); specificity 91% (range 88%–94%).
Not bad, but early on it can miss up to 1 in 4 adults, and it’s poor in kids under 5. Too early? Test again later.
From a systematic review; the authors say these figures probably flatter it in everyday practice.
Source: Infectious mononucleosis: rapid evidence review (American Family Physician 2023)
Ottawa knee rule for a broken bone in the knee
You landed hard on your knee. The doctor asks your age, presses the kneecap and the bony bump on the outside, then checks you can bend it and walk four steps. Any red flag means an X-ray.
Sensitivity 98.5% (range 93%–100%); specificity 48.6% (range 43%–51%).
Just like its ankle cousin: it almost never misses a fracture, and about half of people without one still get sent for an X-ray. A fair trade.
Bachmann 2004 systematic review: 6 studies, 4,249 adults.
Source: Bachmann 2004 systematic review (Ann Intern Med abstract)
#1 · Monday 2 November 2026 Easy
COVID rapid antigen test (RAT) for COVID
Sore throat, runny nose, feeling rubbish. You swab yourself at home.
Sensitivity 73% (range 69%–76%); specificity 99% (range 99%–100%).
Great at false alarms (it barely makes any). Less great at catching COVID: about 1 in 4 people with symptoms test negative. A negative RAT with symptoms is worth repeating.
Pooled across many brands and 109 evaluations in people with symptoms.
Source: Cochrane review (Dinnes 2022), summarised in American Family Physician 2023
Rapid strep test for strep throat
A child with a sore throat gets a quick throat swab at the clinic. Result in minutes.
Sensitivity 86% (range 83%–88%); specificity 95% (range 94%–96%).
Pretty good both ways. It misses about 1 in 7 strep throats, so a negative doesn’t fully rule it out.
Twist: In the Cochrane studies, about 3 in 10 kids with a sore throat had strep.
Children only. Results varied between brands and studies.
Source: Cochrane review: rapid tests for strep throat in children (2016)
Home pregnancy test (done at home) for pregnancy
Period’s late. You wee on the stick at home. Older studies watched real people do it.
Sensitivity 75% (range 64%–85%); no reliable specificity figure.
Trained volunteers caught about 9 in 10 pregnancies, but real people at home missed about 1 in 4. Testing too early is a big reason: if it’s negative and your period still hasn’t come, test again in a few days.
Old studies (1972 to 1993); modern tests may do better. No good pooled figure for false positives, so this round has one slider.
Source: Bastian 1998 meta-analysis, summarised by BestBETs; Cole 2004 study, summarised in American Family Physician
Ottawa ankle rules for a broken bone
You rolled your ankle. The doctor presses a few bony spots and asks you to walk four steps. ‘Positive’ means: get an X-ray.
Sensitivity 98% (range 96%–99%); specificity 32% (range 24%–44%).
A champion rule-out tool. It almost never misses a fracture, but most people it sends for an X-ray are fine. That’s the deal: it still cuts X-rays by about a third.
Specificity varied a lot between studies.
Source: Bachmann 2003 systematic review (BMJ), summarised in American Family Physician
Screening mammogram for breast cancer
A routine screening mammogram, no lumps, no symptoms. Just your two-yearly squish.
Sensitivity 87% (range 85%–89%); specificity 89% (range 87%–91%).
Catches most cancers, but because so few people being screened have cancer, most call-backs turn out fine. A call-back is not a diagnosis.
Twist: In the US screening data, about 1 in 220 screens found a cancer within a year.
US data, 2007 to 2013, 1.6 million screens. Programs and countries differ.
Source: Breast Cancer Surveillance Consortium (US) screening benchmarks