Clinical pathology: urine

77 Kerala MSc MLT Entrance practice questions on Clinical pathology: urine, part of 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 · Hard

   A 30-year-old man with falciparum malaria passes dark urine. Results: blood 3+ on the strip, 0-2 red cells/HPF, plasma pink, serum haptoglobin undetectable, CK normal. What best explains the urine finding?

   1. ABilirubinuria from rapid red cell breakdown
   2. BHaematuria with red cells lysed in the tube
   3. CHaemoglobinuria from intravascular haemolysis
   4. DMyoglobinuria from muscle injury

   Show answerHide answer

   Answer: C · Haemoglobinuria from intravascular haemolysis

   A strongly positive blood pad with almost no red cells means free haem pigment, either haemoglobin or myoglobin. Pink plasma and absent haptoglobin show that haemoglobin is free in the blood, as in the massive intravascular haemolysis of falciparum malaria (blackwater fever). Myoglobin is cleared so fast that plasma stays clear, and CK would be very high. Bilirubin does not react on the blood pad.

   • A: Bilirubin does not give a positive blood pad.
   • B: Lysis in the tube would not make the plasma pink or remove haptoglobin.
   • D: Myoglobinuria gives clear plasma and a very high CK.

2. Question 2 · Easy

   Which reaction does the urine strip nitrite pad use to detect the nitrite made by bacteria?

   1. AThe sodium nitroprusside reaction
   2. BThe pseudoperoxidase reaction
   3. CThe Ehrlich aldehyde reaction
   4. DThe Griess diazotisation reaction

   Show answerHide answer

   Answer: D · The Griess diazotisation reaction

   Nitrite reacts with an aromatic amine in the pad to form a diazonium salt, which couples with a second compound to give a pink colour. This is the Griess reaction. Gram-negative rods that reduce nitrate, such as Escherichia coli, give a positive result if urine has stayed in the bladder for about 4 hours. Any pink colour is reported as positive.

   • A: Nitroprusside is used for ketones.
   • B: Pseudoperoxidase activity is the basis of the blood pad.
   • C: Ehrlich's reagent is used for urobilinogen.

3. Question 3 · Hard

   A random urine has protein 150 mg/dL and creatinine 75 mg/dL. Which protein-to-creatinine ratio, and the daily protein loss it suggests, is correct?

   1. A0.5; about 0.5 g protein a day
   2. B0.02; within normal limits
   3. C2.0; about 2 g protein a day
   4. D20; nephrotic-range proteinuria

   Show answerHide answer

   Answer: C · 2.0; about 2 g protein a day

   The ratio is protein divided by creatinine in the same units: 150 / 75 = 2.0 mg/mg. Because a person excretes roughly 1 g of creatinine a day, a ratio in mg/mg approximates grams of protein per day, so about 2 g/day. Inverting the ratio gives 0.5, and slipping a decimal gives 20 or 0.02. A ratio above 0.2 is abnormal and above about 3.5 is nephrotic range.

   • A: 0.5 comes from dividing creatinine by protein.
   • B: 0.02 comes from a factor-of-100 error and would wrongly be read as normal.
   • D: 20 comes from a factor-of-ten error.

4. Question 4 · Hard

   A man passes 7 L of dilute urine a day. After 8 hours without fluid, urine osmolality is 180 mOsm/kg; one hour after desmopressin it is 620 mOsm/kg. These results point to:

   1. APrimary polydipsia
   2. BNephrogenic diabetes insipidus
   3. COsmotic diuresis from glycosuria
   4. DCentral (cranial) diabetes insipidus

   Show answerHide answer

   Answer: D · Central (cranial) diabetes insipidus

   Without fluid, the urine stays dilute, so the kidney is not concentrating despite dehydration. A large rise after desmopressin shows that the tubules respond to ADH, so the defect is a lack of ADH from the pituitary. In nephrogenic diabetes insipidus the urine stays dilute after desmopressin. In primary polydipsia the urine concentrates during fluid deprivation.

   • A: Primary polydipsia concentrates the urine during deprivation.
   • B: Nephrogenic diabetes insipidus shows no rise after desmopressin.
   • C: Osmotic diuresis gives a urine osmolality near or above plasma, not 180 mOsm/kg.

5. Question 5 · Hard

   A urine left uncapped overnight smells of ammonia. The strip shows pH 9.0 and protein 2+, but the sulphosalicylic acid test is negative. The most likely explanation is:

   1. ABence Jones protein missed by the acid test
   2. BX-ray contrast medium reacting on the strip
   3. CBacteria digesting albumin before the acid test
   4. DAlkaline urine overcoming the protein pad buffer

   Show answerHide answer

   Answer: D · Alkaline urine overcoming the protein pad buffer

   The protein pad relies on a buffer that holds it near pH 3. Highly alkaline urine, here from bacterial urease splitting urea on standing, overwhelms the buffer and changes the indicator colour without protein, a false positive. The sulphosalicylic acid test is not affected by pH and is negative. A fresh sample should be tested.

   • A: Bence Jones protein is detected by the acid test and is poorly detected by the strip, the reverse pattern.
   • B: Contrast media give false positives with the acid test, not the strip.
   • C: Bacterial digestion would lower both tests, not only the acid test.

6. Question 6 · Medium

   A patient taking high-dose vitamin C has a large amount of ascorbic acid in the urine. Which reagent strip results may be falsely low?

   1. AProtein, pH and specific gravity
   2. BSpecific gravity and ketones
   3. CBlood, glucose, bilirubin and nitrite
   4. DKetones, protein and urobilinogen

   Answer and explanation in LearnFree account

7. Question 7 · Medium

   A refrigerated urine has a heavy sediment that dissolves when the tube is warmed to about 60 °C. What was the sediment most likely to be?

   1. AAmorphous phosphates
   2. BCalcium oxalate
   3. CAmorphous urates
   4. DTriple phosphate

   Answer and explanation in LearnFree account

8. Question 8 · Easy

   A urine sample forms a persistent yellow foam when shaken. What does it most likely contain?

   1. AHaemoglobin
   2. BUrobilinogen
   3. CProtein
   4. DBilirubin

   Answer and explanation in LearnFree account

9. Question 9 · Easy

   Which protein does the urine reagent strip protein pad detect best?

   1. AHaemoglobin
   2. BBence Jones light chains
   3. CImmunoglobulin G
   4. DAlbumin

   Answer and explanation in LearnFree account

10. Question 10 · Medium

    Which confirmatory test for urine bilirubin uses a diazo reaction on an absorbent mat and is more sensitive than the reagent strip?

    1. AIctotest tablet test
    2. BFouchet's test
    3. CGmelin's nitric acid test
    4. DHay's sulphur test

    Answer and explanation in LearnFree account

11. Question 11 · Medium

    The sodium nitroprusside ketone pad of a urine strip reacts mainly with:

    1. AAcetoacetic acid
    2. BAcetone alone
    3. CPyruvic acid
    4. DBeta-hydroxybutyric acid

    Answer and explanation in LearnFree account

12. Question 12 · Medium

    Through which property does the urine strip blood pad detect haemoglobin?

    1. APseudoperoxidase activity
    2. BReduction of a copper salt
    3. CGlobin binding to a dye
    4. DIron reacting with ferricyanide

    Answer and explanation in LearnFree account

13. Question 13 · Medium

    Why may casts be missed in a urine left at room temperature for several hours?

    1. AAre covered by a layer of growing bacteria
    2. BDissolve as the urine turns alkaline and dilute
    3. CShrink until they look like mucus threads
    4. DSettle so firmly that they cannot be resuspended

    Answer and explanation in LearnFree account

14. Question 14 · Hard

    A woman with uncontrolled diabetes has urine glucose 4+ (over 2,000 mg/dL), specific gravity 1.040 and leukocyte esterase negative. The sediment shows 30-40 granular white cells/HPF. What is the best explanation?

    1. AThe cells are renal tubular cells, not white cells
    2. BThe white cells are lymphocytes without esterase
    3. CHigh glucose and specific gravity suppressing the pad
    4. DThe sediment was overcentrifuged and concentrated

    Answer and explanation in LearnFree account

15. Question 15 · Easy

    The leukocyte esterase pad of a urine strip detects esterase from:

    1. AGranulocytes, even when lysed
    2. BGram-negative bacteria
    3. CRenal tubular epithelial cells
    4. DLymphocytes in the urine

    Answer and explanation in LearnFree account

16. Question 16 · Medium

    Repeated urine samples from a patient have a specific gravity fixed near 1.010 whatever the fluid intake. What does this indicate?

    1. ADiabetes insipidus from a lack of ADH secretion
    2. BHeavy proteinuria in nephrotic syndrome
    3. CLoss of the kidney's ability to concentrate and dilute
    4. DDehydration with intact tubular function

    Answer and explanation in LearnFree account

17. Question 17 · Medium

    A timed urine for urobilinogen is best collected in the early afternoon (about 2-4 pm) because:

    1. AThe urine is most concentrated at that time of day
    2. BUrobilinogen excretion peaks then, after the post-meal alkaline tide
    3. CBilirubin is lowest in the urine at that time of day
    4. DBacteria that destroy urobilinogen are fewest then

    Answer and explanation in LearnFree account

18. Question 18 · Easy

    A urine sample cannot be examined within 2 hours. The preferred general method to preserve it is:

    1. ALeaving it at room temperature, capped
    2. BRefrigeration at 2-8 °C
    3. CAdding formalin
    4. DFreezing at -20 °C

    Answer and explanation in LearnFree account

19. Question 19 · Easy

    Which urine specimen is the most concentrated and therefore preferred for detecting small amounts of abnormal constituents?

    1. AFirst morning specimen
    2. BRandom daytime specimen
    3. CTwo-hour postprandial specimen
    4. DMidday specimen after drinking water

    Answer and explanation in LearnFree account

20. Question 20 · Medium

    In Heller's test, concentrated nitric acid is layered under urine. A white ring at the junction of the two layers indicates:

    1. AKetone bodies reacting with nitrate
    2. BBilirubin oxidised to biliverdin
    3. CGlucose charred by the strong acid
    4. DProtein precipitated by the acid

    Answer and explanation in LearnFree account

21. Question 21 · Hard

    A diabetic's random urine has albumin 6 mg/dL and creatinine 100 mg/dL. Which albumin-creatinine ratio, and category, is correct?

    1. A6 mg/g, normal albuminuria
    2. B600 mg/g, severely increased albuminuria
    3. C60 mg/g, moderately increased albuminuria
    4. D60 mg/g, normal albuminuria

    Answer and explanation in LearnFree account

22. Question 22 · Easy

    The active compound in Ehrlich's reagent, used to test urine for urobilinogen, is:

    1. Ap-dimethylaminobenzaldehyde
    2. BSodium nitroprusside
    3. Co-toluidine
    4. DDiazotised sulphanilic acid

    Answer and explanation in LearnFree account

23. Question 23 · Medium

    Brown sheaves of needle-like crystals appear in the acid urine of a patient being treated for a urinary infection. What should be checked first?

    1. AWhether the patient is taking a sulphonamide drug
    2. BA cyanide-nitroprusside test for cystine
    3. CThe serum uric acid level
    4. DLiver function tests for tyrosine

    Answer and explanation in LearnFree account

24. Question 24 · Easy

    The pH of normal random urine samples lies in the range of:

    1. A7.35-7.45
    2. B2.0-3.5
    3. C4.5-8.0
    4. D8.5-10.0

    Answer and explanation in LearnFree account

25. Question 25 · Medium

    Why should the urine sediment be scanned for casts under the low-power objective with the condenser iris partly closed?

    1. ACasts are too large to fit in a high-power field
    2. BBright light dissolves the protein matrix of the casts
    3. CHyaline casts have a refractive index close to urine and fade in bright light
    4. DReduced light makes red cells and crystals disappear

    Answer and explanation in LearnFree account