Lab Medicine

lab medicine questions

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Jul 2
A patient with metabolic acidosis has HCO3- 12 mmol/L and a measured pCO2 of 40 mmHg. Applying Winter's formula, what is the acid–base interpretation?
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Jul 1
In a critically ill patient with diabetic ketoacidosis, creatinine measured by the kinetic Jaffe method reads higher than by an enzymatic assay. Which interferent classically causes positive (falsely high) interference with the Jaffe reaction?
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Jun 30
A patient with known haemolytic anaemia has an HbA1c that seems implausibly low despite documented hyperglycaemia. Why is HbA1c unreliable here, and what is a better measure of medium-term control?
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Jun 29
A euvolaemic patient with hyponatraemia (Na 122) has low serum osmolality (260), inappropriately high urine osmolality (450), urine sodium 60 mmol/L, and normal thyroid and cortisol. What is the diagnosis?
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Jun 28
Two patients have hypercalcaemia. Patient A: high Ca, low phosphate, HIGH PTH. Patient B: high Ca, low phosphate, SUPPRESSED PTH, with known squamous lung carcinoma. What distinguishes their mechanisms?
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Jun 27
An older patient with bone pain has anaemia, a high total protein with a narrow-based spike in the gamma region on serum protein electrophoresis, calcium 2.9 mmol/L, raised creatinine, and rouleaux on the film. Which test best types and quantifies the abnormal protein and adds prognostic information?
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Jun 26
A patient with a pulmonary–renal syndrome has a cytoplasmic (c-ANCA) immunofluorescence pattern and antibodies to proteinase-3 (PR3) on antigen-specific ELISA. Which condition is most associated?
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Jun 25
Seven days after starting unfractionated heparin, a patient's platelet count falls by 60% and a new DVT appears. Which laboratory pattern supports heparin-induced thrombocytopenia (HIT)?
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Jun 24
A patient with recurrent venous thrombosis has a prolonged aPTT that does not correct on 1:1 mixing. A dilute Russell viper venom time (dRVVT) is prolonged and corrects when excess phospholipid is added. What does this confirm?
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Jun 23
A patient with anaemia (haematocrit 25%) has a reticulocyte count of 4%. After correcting for the anaemia and reticulocyte maturation, is the marrow response adequate?
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Jun 22
A fasting lipid panel reports total cholesterol 6.0, HDL 1.0, and triglycerides 5.0 mmol/L. Why should a calculated (Friedewald) LDL not be reported for this sample?
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Jun 21
In the workup of a microcytic anaemia, which iron-study constellation best fits anaemia of chronic disease rather than iron deficiency?
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Jun 20
48 hours after starting chemotherapy for a bulky high-grade lymphoma, a patient develops raised potassium, raised phosphate, raised uric acid, low calcium, and rising creatinine. What is the diagnosis, and why is the calcium low?
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Jun 19
A patient with anaemia has this constellation: elevated LDH, low/undetectable haptoglobin, raised unconjugated (indirect) bilirubin, and a HIGH reticulocyte count. What does this indicate, and what is the next test?
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Jun 18
A clinically euthyroid patient on high-dose biotin supplements has a suppressed TSH with elevated free T4 and free T3 and a positive TRAb, mimicking Graves disease. Which mechanism best explains this pattern?
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Jun 17
A patient with a bulky germ-cell tumour has a serum β-hCG reported as only mildly elevated, discordant with imaging. On 1:100 dilution the measured β-hCG is dramatically higher. Which phenomenon explains the falsely low initial result?
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Jun 16
A patient with multiple myeloma and very high total protein has a serum sodium of 125 mmol/L on the chemistry analyser (indirect ISE), but the blood gas analyser (direct ISE) reports 140 mmol/L. What explains the discrepancy?
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Jun 15
A patient has a high anion gap metabolic acidosis. Measured serum osmolality is 320 mOsm/kg, with Na+ 140, glucose 5.0, and urea 5.0 mmol/L (ethanol undetectable). How should the osmolar gap be interpreted?
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Jun 14
A patient has a microcytic, hypochromic anemia (low MCV, low MCH) with a low serum ferritin. What is the most likely diagnosis?
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Jun 13
A patient presents with metabolic acidosis. Serum Na+ is 140, Cl- is 100, and HCO3- is 12 mmol/L. How should the calculated anion gap be interpreted?
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