Lab Medicine

lab medicine questions

3 members1 open

Today's question

Closes in 3h10 points

A patient has a Coombs-NEGATIVE haemolytic anaemia with spherocytes on the film, a raised MCHC, splenomegaly, and a family history. Which confirmatory test supports hereditary spherocytosis?

It takes 30 seconds.

Answer today's question

Jul 27
Two patients have a prolonged PT. To distinguish vitamin K deficiency/warfarin from hepatocellular synthetic failure, clotting factors are measured. Which finding indicates liver disease rather than vitamin K deficiency?
Closed
Jul 26
A septic patient develops oozing from venepuncture sites. Labs: prolonged PT and aPTT, LOW fibrinogen, markedly RAISED D-dimer, falling platelets, and schistocytes on the film. What is the diagnosis?
Closed
Jul 25
A patient with lifelong easy bruising and mucosal bleeding has a normal platelet count, a normal PT, a mildly prolonged aPTT, and a low ristocetin cofactor activity (VWF:RCo) with a proportionally reduced VWF antigen. What is the diagnosis?
Closed
Jul 24
To investigate suspected coeliac disease, IgA anti-tissue-transglutaminase (tTG) is requested. Why must a total IgA be measured at the same time, and what should be done if it is low?
Closed
Jul 23
A middle-aged woman with fatigue, pruritus and a cholestatic pattern (raised ALP and GGT) is positive for anti-mitochondrial antibodies (AMA, M2 subtype) with a raised IgM. Which diagnosis is most likely?
Closed
Jul 22
Shortly after anaesthetic induction a patient develops hypotension, bronchospasm and urticaria. Which laboratory test, and with what timing, best confirms mast-cell degranulation (anaphylaxis)?
Closed
Jul 21
Ascitic fluid analysis gives a serum-ascites albumin gradient (SAAG) of 15 g/L (≥ 11 g/L). What does a high SAAG indicate about the cause of the ascites?
Closed
Jul 20
A patient with chronic liver disease has AST 180 and ALT 70 U/L (AST:ALT ≈ 2.6), a raised GGT, and macrocytosis. Which aetiology does this pattern most suggest?
Closed
Jul 19
An oliguric patient with acute kidney injury has a urine sodium of 10 mmol/L and a fractional excretion of sodium (FENa) of 0.5%, and has not received diuretics. What does this suggest?
Closed
Jul 18
A patient had a severe thunderclap headache 12 hours ago; the CT head is normal. Lumbar puncture CSF is centrifuged and the supernatant is yellow (xanthochromia positive) on spectrophotometry. What does this indicate, and why does timing matter?
Closed
Jul 17
A febrile patient's CSF shows: high opening pressure, > 1000 white cells/µL (neutrophil-predominant), protein 2.5 g/L (high), and a CSF:serum glucose ratio of 0.2 (low). Which pattern is this, and why is the glucose low?
Closed
Jul 16
A child with encephalopathy has a markedly elevated venous ammonia, but the result is questioned because of sample handling. Which preanalytical practice is essential for a reliable ammonia measurement?
Closed
Jul 15
A patient with a platelet count of 900 × 10⁹/L has a serum potassium of 6.2 mmol/L, but a simultaneously drawn heparinised plasma (or blood gas) potassium is 4.4 mmol/L, with a normal ECG. What explains the discrepancy?
Closed
Jul 14
A well, asymptomatic woman with regular menses and no galactorrhoea has a persistently 'raised' prolactin. After polyethylene glycol (PEG) precipitation the recovered prolactin is < 40% and now within range. What was the cause?
Closed
Jul 13
In screening for Cushing's syndrome, a patient takes 1 mg dexamethasone at 11 p.m. and the 8 a.m. serum cortisol fails to suppress below 50 nmol/L. How is this interpreted, and what can cause a false-positive?
Closed
Jul 12
A patient with resistant hypertension and unprovoked hypokalaemia has an elevated aldosterone:renin ratio (ARR) with suppressed plasma renin. Which condition does this suggest, and which preanalytical factors most affect the result?
Closed
Jul 11
A hyponatraemic, hyperkalaemic patient with hypotension and fatigue has a low 9 a.m. cortisol. A 250 µg Synacthen (cosyntropin) test shows the cortisol fails to rise above ~450 nmol/L at 30 minutes. What does this indicate, and which test localises the lesion?
Closed
Jul 4
To investigate a suspected phaeochromocytoma, which test offers the highest sensitivity, and which preanalytical factor most affects its reliability?
Closed
Jul 3
A man develops acute haemolysis after an infection. A quantitative G6PD assay drawn DURING the acute episode is reported as normal, yet G6PD deficiency is still strongly suspected. Why can the assay be falsely normal, and when should it be repeated?
Closed