Urine examination

55 Lab technician recruitment practice questions on Urine examination, part of Clinical Pathology. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

1. Question 1 · Medium

   A pink precipitate called brick dust forms in refrigerated acid urine. What is it?

   1. ABilirubin crystals
   2. BAmorphous urates
   3. CCalcium carbonate
   4. DAmorphous phosphates

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   Answer: B · Amorphous urates

   Amorphous urates precipitate in acid urine on cooling and are often coloured pink by uroerythrin. They dissolve on warming to 60 °C or in alkali.

   • A: Bilirubin crystals are yellow-brown needles.
   • C: Calcium carbonate forms in alkaline urine and fizzes with acid.
   • D: Amorphous phosphates are white and form in alkaline urine.

2. Question 2 · Hard

   A diabetic in coma has a blood ketone level that is very high, but Rothera's test is only weakly positive. What is the reason?

   1. AThe urine is too concentrated
   2. BAcetone has evaporated from blood
   3. CMost ketone is beta-hydroxybutyrate, which nitroprusside misses
   4. DRothera's reagent is only sensitive to glucose

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   Answer: C · Most ketone is beta-hydroxybutyrate, which nitroprusside misses

   In severe ketoacidosis with lactic acidosis or shock, the redox state favours beta-hydroxybutyrate, which nitroprusside does not detect. The test can even become more positive as treatment converts it back to acetoacetate.

   • A: Concentration would increase, not decrease, reaction.
   • B: Acetone gives only a weak reaction anyway.
   • D: Rothera's test is for ketones, not glucose.

3. Question 3 · Medium

   An unpreserved specimen sits on the bench through the afternoon. Which pair of chemical changes is expected?

   1. ApH rises and glucose falls
   2. BBilirubin rises
   3. CpH falls and glucose rises
   4. DCells and casts increase

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   Answer: A · pH rises and glucose falls

   Bacteria multiply, split urea to ammonia and use glucose, so pH rises and glucose falls. Cells and casts lyse, bilirubin oxidises in light and turbidity increases.

   • B: Bilirubin falls because of photo-oxidation.
   • C: Bacterial urease makes urine alkaline, not acid.
   • D: Cells and casts break down, they do not increase.

4. Question 4 · Medium

   Dark brown or black urine on standing, with a positive Benedict's test, suggests which disorder?

   1. AMaple syrup urine disease
   2. BPhenylketonuria
   3. CPorphyria cutanea tarda
   4. DAlkaptonuria

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   Answer: D · Alkaptonuria

   Homogentisic acid oxidises in air, especially in alkaline urine, and turns black. It also reduces copper in Benedict's reagent. Melanin also darkens urine but does not reduce copper.

   • A: Maple syrup disease gives a sweet odour.
   • B: PKU gives a mousy odour and a green ferric chloride test.
   • C: Porphyria gives red or port-wine urine.

5. Question 5 · Hard

   Calculate daily excretion: total collection 1.5 L, measured protein concentration 200 mg/dL.

   1. A1.5 g/day
   2. B3 g/day
   3. C30 g/day
   4. D0.3 g/day

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   Answer: B · 3 g/day

   200 mg/dL is 2000 mg per litre, so 1.5 L contains 3000 mg = 3 g. More than 3.5 g/day in adults is nephrotic-range proteinuria.

   • A: This uses the volume without the concentration.
   • C: This is ten times too high.
   • D: This misses a factor of ten in converting dL to L.

6. Question 6 · Easy

   Boiling the upper third of a tube, then adding dilute acid, screens a specimen for what?

   1. AKetone bodies
   2. BGlucose
   3. CBile salts
   4. DProtein

   Answer and explanation in LearnFree account

7. Question 7 · Medium

   Which cast is most characteristic of acute glomerulonephritis?

   1. AHyaline cast
   2. BWhite cell cast
   3. CWaxy cast
   4. DRed cell cast

   Answer and explanation in LearnFree account

8. Question 8 · Medium

   Which pair of crystals in urine indicates severe liver disease?

   1. ACalcium oxalate and amorphous urates
   2. BCystine and uric acid
   3. CTriple phosphate and calcium carbonate
   4. DLeucine and tyrosine

   Answer and explanation in LearnFree account

9. Question 9 · Easy

   The glucose pad of a reagent strip uses which enzymes?

   1. AHexokinase and G6PD
   2. BLactase and galactose oxidase
   3. CEsterase and diazonium
   4. DGlucose oxidase and peroxidase

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10. Question 10 · Medium

    A puffy-faced child's sediment contains lipid-laden tubular cells that show bright crosses under polarised light. Which diagnosis fits?

    1. ANephrotic syndrome
    2. BRenal stone
    3. CAcute cystitis
    4. DProstatitis

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11. Question 11 · Medium

    Copper reduction turns orange, yet the enzyme-based dipstick square stays unchanged. What best explains this mismatch?

    1. AGlucose above the strip's upper limit
    2. BA non-glucose reducing sugar such as galactose
    3. CA strip stored in a closed container
    4. DUrine tested within one hour

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12. Question 12 · Medium

    Broad, waxy casts are associated with which condition?

    1. AStrenuous exercise
    2. BEarly pregnancy
    3. CAdvanced chronic renal failure
    4. DAcute cystitis

    Answer and explanation in LearnFree account

13. Question 13 · Medium

    Ehrlich's aldehyde reagent used to detect urobilinogen contains which compound?

    1. ACopper sulphate
    2. Bp-Dimethylaminobenzaldehyde
    3. CFerric chloride in trichloroacetic acid
    4. DSodium nitroprusside

    Answer and explanation in LearnFree account

14. Question 14 · Medium

    In obstructive jaundice, which urine pattern is expected?

    1. ABilirubin positive, urobilinogen absent
    2. BBilirubin absent, urobilinogen normal
    3. CBilirubin absent, urobilinogen raised
    4. DBoth bilirubin and urobilinogen absent

    Answer and explanation in LearnFree account

15. Question 15 · Easy

    Envelope-shaped crystals seen in acid urine are which type?

    1. AUric acid
    2. BCystine
    3. CCalcium oxalate dihydrate
    4. DTriple phosphate

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16. Question 16 · Medium

    Which is NOT a cause of red urine with a negative reagent strip blood pad?

    1. AMyoglobinuria
    2. BBeetroot ingestion
    3. CPorphyrins
    4. DRifampicin therapy

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17. Question 17 · Easy

    Which sample is preferred for routine urine examination and pregnancy testing?

    1. APost-prandial sample
    2. BTwenty-four hour sample
    3. CEarly morning sample
    4. DRandom afternoon sample

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18. Question 18 · Easy

    Hay's test for bile salts depends on which property of bile salts?

    1. APrecipitation by heat
    2. BOxidation to biliverdin
    3. CLowering of surface tension
    4. DReduction of copper ions

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19. Question 19 · Easy

    Tetrabromophenol blue on a dipstick changes from yellow to green-blue. Which chemical principle explains that colour change?

    1. ADiazo coupling
    2. BPeroxidase activity
    3. CCopper reduction
    4. DProtein error of indicators

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20. Question 20 · Easy

    Which ketone body gives no reaction in Rothera's nitroprusside test?

    1. ABeta-hydroxybutyric acid
    2. BAcetoacetic acid
    3. CNone; all three react equally
    4. DAcetone

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21. Question 21 · Medium

    Indoxyl ester hydrolysis on a dipstick gives a purple colour. Esterase from which cell types produces it?

    1. ANeutrophils, eosinophils and monocytes
    2. BRenal tubular epithelial cells
    3. CLymphocytes only
    4. DRed blood cells

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22. Question 22 · Medium

    Hydrometer reading: 1.020. Calibration mark: 15 °C. Specimen temperature: 30 °C. What corrected density should be reported?

    1. A1.015
    2. B1.020
    3. C1.025
    4. D1.030

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23. Question 23 · Hard

    A urine with pH 8.5 contains coffin-lid crystals, many bacteria and a strong ammonia smell. Which organism is most likely?

    1. AEnterococcus faecalis
    2. BProteus mirabilis
    3. CEscherichia coli
    4. DCandida albicans

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24. Question 24 · Easy

    After boiling, cloudiness appears in an alkaline specimen. What purpose does adding dilute acid then serve?

    1. ATo raise the urine pH
    2. BTo precipitate glucose
    3. CTo oxidise bilirubin
    4. DTo dissolve phosphate turbidity

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25. Question 25 · Medium

    Rothera's test turns positive in urine of a well-nourished patient. Which situation is the most likely cause?

    1. AProlonged fasting or vomiting
    2. BIron supplements
    3. CHigh carbohydrate diet
    4. DExcess fluid intake

    Answer and explanation in LearnFree account