Clinical pathology: urine analysis

44 Kerala PSC Lab Technician Gr II practice questions on Clinical pathology: urine analysis, 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.

Question 1 · Easy
Hay's sulphur test is used to detect which substance in urine?
1. ABile salts
2. BBile pigments
3. CUrobilinogen
4. DKetone bodies
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Answer: A · Bile salts
Bile salts lower the surface tension of urine. Sulphur powder sprinkled on the surface sinks when bile salts are present but floats on normal urine. Bile salts appear in the urine in obstructive (cholestatic) jaundice. Bile pigment (bilirubin) is tested separately by Fouchet's test or a reagent strip.
- B: Bile pigments (bilirubin) are detected by Fouchet's or Gmelin's test.
- C: Urobilinogen is detected with Ehrlich's aldehyde reagent.
- D: Ketone bodies are detected by Rothera's test.
Question 2 · Easy
Which disorder makes freshly passed urine of normal colour turn black on standing in air?
1. ACystinuria
2. BPhenylketonuria
3. CMaple syrup urine disease
4. DAlkaptonuria
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Answer: D · Alkaptonuria
In alkaptonuria, homogentisate oxidase is missing and homogentisic acid is excreted in the urine. On standing, especially when the urine is alkaline, homogentisic acid oxidises to a black pigment. It also reduces Benedict's reagent, giving a positive result with a dark precipitate. Black urine can also occur in melanuria from metastatic melanoma.
- A: Cystinuria causes hexagonal crystals and stones, not a colour change.
- B: Phenylketonuria gives a mousy odour and a green ferric chloride test, not black urine.
- C: Maple syrup urine disease gives a sweet, burnt-sugar odour.
Question 3 · Medium
All of the following sugars give a positive Benedict's test EXCEPT:
1. AFructose
2. BLactose
3. CGalactose
4. DSucrose
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Answer: D · Sucrose
Benedict's test detects reducing sugars, which have a free aldehyde or ketone group that reduces blue cupric ions to red cuprous oxide on boiling in alkali. Glucose, fructose, galactose, lactose and maltose are all reducing sugars. In sucrose the reducing groups of glucose and fructose are joined in the glycosidic bond, so it does not react unless first hydrolysed. A positive Benedict's test therefore does not prove glucose; a glucose oxidase strip is specific.
- A: Fructose is a reducing sugar and gives a positive test.
- B: Lactose has a free reducing group and gives a positive test, for example in late pregnancy and lactation.
- C: Galactose is a reducing sugar and gives a positive test, as in galactosemia.
Question 4 · Medium
In the heat and acetic acid test, a cloud that forms on boiling but clears with a few drops of acetic acid is due to:
1. AAlbumin
2. BBence Jones protein
3. CPhosphates
4. DGlobulins
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Answer: C · Phosphates
The upper part of the urine in a test tube is boiled; proteins coagulate, and phosphates also come out of solution as a white cloud. A few drops of dilute acetic acid dissolve phosphates (and carbonates), so a phosphate cloud clears, while coagulated protein remains. The acid also brings the urine near the isoelectric point of the proteins, so small amounts precipitate better. The lower, unheated part of the tube serves as the control.
- A: Albumin coagulates on heating and its cloud persists after the acid is added.
- B: Bence Jones protein precipitates at 40-60 °C and redissolves near boiling, not with acid.
- D: Globulins also coagulate on heating and do not dissolve in acetic acid.
Question 5 · Medium
A woman has fever, flank pain and pus cells in her urine. Which urine finding best shows that the pus cells come from the kidney?
1. AMany bacteria
2. BSquamous epithelial cells
3. CWhite cell casts
4. DClumps of pus cells
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Answer: C · White cell casts
Casts form only in the renal tubules, where Tamm-Horsfall protein gels around whatever cells are present. White cells inside a cast therefore prove that they were in the tubules, as in acute pyelonephritis or interstitial nephritis. Pus cells and bacteria alone may come from anywhere in the urinary tract, including the bladder. Squamous cells usually show contamination from the vagina or urethra.
- A: Bacteria are found in both lower and upper urinary infection, and in contaminated samples.
- B: Squamous epithelial cells come from the urethra or vagina and suggest contamination.
- D: Clumps of pus cells occur in any urinary infection, including cystitis.
Question 6 · Easy
What does Rothera's test on urine detect?
1. ABile salts
2. BBeta-hydroxybutyric acid
3. CReducing sugars
4. DAcetoacetic acid and acetone
Answer and explanation in LearnFree account
Question 7 · Medium
A 64-year-old man with back pain and anemia has urine protein negative by reagent strip but positive by sulphosalicylic acid. Which protein is most likely present?
1. AFree light chains (Bence Jones)
2. BAlbumin
3. CTamm-Horsfall protein
4. DHemoglobin
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Question 8 · Easy
Fouchet's reagent for urine bilirubin contains trichloroacetic acid and:
1. AFerric chloride
2. BSulphosalicylic acid
3. CSodium nitroprusside
4. DCopper sulphate
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Question 9 · Hard
A 3-week-old baby has vomiting, poor feeding, jaundice and an enlarged liver. The urine is positive with Benedict's test but negative with a glucose oxidase strip. The most likely diagnosis is:
1. AGalactosemia
2. BAlkaptonuria
3. CPhenylketonuria
4. DRenal glycosuria
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Question 10 · Hard
A urinometer calibrated at 20 °C reads 1.020 in urine at 32 °C that contains 2 g/dL glucose. Correct by adding 0.001 for every 3 °C above the calibration temperature and subtracting 0.004 for each g/dL of glucose. The true specific gravity is:
1. A1.024
2. B1.008
3. C1.012
4. D1.016
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Question 11 · Medium
Oval fat bodies and fatty casts showing Maltese crosses under polarized light are typical of which condition?
1. AAcute cystitis
2. BNephrotic syndrome
3. CAcute pyelonephritis
4. DRenal tuberculosis
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Question 12 · Hard
A 23-year-old man was trapped under a collapsed wall for 6 hours. His urine is reddish-brown, and the reagent strip shows blood 3+, but the sediment has no red cells. His plasma is clear and serum CK is 30,000 U/L. The urine colour is most likely due to:
1. APorphyrins
2. BHemoglobin
3. CMyoglobin
4. DBilirubin
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Question 13 · Easy
Which crystals appear as colourless, envelope-shaped octahedra in acidic urine?
1. AUric acid
2. BTriple phosphate
3. CCystine
4. DCalcium oxalate
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Question 14 · Medium
Why can a nitroprusside reagent strip underestimate ketosis in severe diabetic ketoacidosis?
1. AIt does not detect beta-hydroxybutyrate
2. BGlucose in the urine blocks the reaction
3. CIt reacts only with acetone, not acetoacetate
4. DKetones are destroyed by the low urine pH
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Question 15 · Easy
In an adult, what is a urine output of less than 400 mL in 24 hours called?
1. APolyuria
2. BNocturia
3. CAnuria
4. DOliguria
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Question 16 · Easy
Which reagent is used in Gmelin's test for bile pigments in urine?
1. ASodium nitroprusside
2. BConcentrated nitric acid
3. CFerric chloride
4. DSulphur powder
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Question 17 · Medium
Large doses of vitamin C can make a reagent strip test falsely negative for:
1. ASpecific gravity
2. BProtein
3. CpH
4. DGlucose
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Question 18 · Easy
The protein pad of a urine reagent strip works on the principle of:
1. AProtein error of indicators
2. BDiazo coupling reaction
3. CDouble indicator system
4. DPeroxidase activity of heme
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Question 19 · Medium
A diabetic patient's urine with 3 g/dL glucose reads 1.030 on the urinometer but 1.015 on the reagent strip. Why do the readings differ?
1. AThe strip responds only to ionic solutes
2. BThe strip measures osmolality, not density
3. CGlucose bleaches the dye on the strip pad
4. DThe urinometer was not corrected for temperature
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Question 20 · Hard
A 60-year-old woman's urine is tested after standing uncapped at room temperature for 8 hours. It smells of ammonia: pH 8.5, nitrite positive, glucose negative by strip. Her blood glucose at collection was 290 mg/dL. What best explains the urine findings?
1. ABacterial growth in the delayed sample
2. BAlkaline tide after a meal
3. CA raised renal threshold for glucose
4. DRenal tubular acidosis
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Question 21 · Hard
A 6-year-old girl has vomited and eaten little for 3 days. Blood glucose is 72 mg/dL. Her urine gives a strong purple ring with Rothera's test, Benedict's test remains blue and the glucose oxidase strip is negative. The most likely explanation is:
1. AGalactosemia
2. BStarvation ketosis
3. CRenal glycosuria
4. DDiabetic ketoacidosis
Answer and explanation in LearnFree account
Question 22 · Medium
In hemolytic jaundice, the urine typically shows:
1. ABoth bilirubin and bile salts
2. BNeither bilirubin nor urobilinogen
3. CRaised urobilinogen, no bilirubin
4. DBilirubin present, no urobilinogen
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Question 23 · Hard
An 8-year-old boy had a sore throat 2 weeks ago. He now has puffy eyes, raised blood pressure and scanty smoky urine. Urine protein 1+, sediment shows many red cells and red cell casts. The most likely diagnosis is:
1. AAcute bacterial pyelonephritis
2. BObstructing renal calculus
3. CPost-streptococcal glomerulonephritis
4. DMinimal change nephrotic syndrome
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Question 24 · Easy
Benedict's test for reducing sugars in urine depends on the reduction of:
1. AFerric ions to ferrous ions
2. BNitroprusside to a purple complex
3. CCupric ions to cuprous oxide
4. DSilver ions to metallic silver
Answer and explanation in LearnFree account
Question 25 · Easy
Colourless hexagonal plates in acidic urine point to which disorder?
1. AGout
2. BAlkaptonuria
3. CCystinuria
4. DPhenylketonuria
Answer and explanation in LearnFree account

19 more Clinical pathology: urine analysis questions

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Clinical pathology: urine analysis

Hay's sulphur test is used to detect which substance in urine?

Which disorder makes freshly passed urine of normal colour turn black on standing in air?

All of the following sugars give a positive Benedict's test EXCEPT:

In the heat and acetic acid test, a cloud that forms on boiling but clears with a few drops of acetic acid is due to:

A woman has fever, flank pain and pus cells in her urine. Which urine finding best shows that the pus cells come from the kidney?

What does Rothera's test on urine detect?

A 64-year-old man with back pain and anemia has urine protein negative by reagent strip but positive by sulphosalicylic acid. Which protein is most likely present?

Fouchet's reagent for urine bilirubin contains trichloroacetic acid and:

A 3-week-old baby has vomiting, poor feeding, jaundice and an enlarged liver. The urine is positive with Benedict's test but negative with a glucose oxidase strip. The most likely diagnosis is:

A urinometer calibrated at 20 °C reads 1.020 in urine at 32 °C that contains 2 g/dL glucose. Correct by adding 0.001 for every 3 °C above the calibration temperature and subtracting 0.004 for each g/dL of glucose. The true specific gravity is:

Oval fat bodies and fatty casts showing Maltese crosses under polarized light are typical of which condition?

A 23-year-old man was trapped under a collapsed wall for 6 hours. His urine is reddish-brown, and the reagent strip shows blood 3+, but the sediment has no red cells. His plasma is clear and serum CK is 30,000 U/L. The urine colour is most likely due to:

Which crystals appear as colourless, envelope-shaped octahedra in acidic urine?

Why can a nitroprusside reagent strip underestimate ketosis in severe diabetic ketoacidosis?

In an adult, what is a urine output of less than 400 mL in 24 hours called?

Which reagent is used in Gmelin's test for bile pigments in urine?

Large doses of vitamin C can make a reagent strip test falsely negative for:

The protein pad of a urine reagent strip works on the principle of:

A diabetic patient's urine with 3 g/dL glucose reads 1.030 on the urinometer but 1.015 on the reagent strip. Why do the readings differ?

A 60-year-old woman's urine is tested after standing uncapped at room temperature for 8 hours. It smells of ammonia: pH 8.5, nitrite positive, glucose negative by strip. Her blood glucose at collection was 290 mg/dL. What best explains the urine findings?

A 6-year-old girl has vomited and eaten little for 3 days. Blood glucose is 72 mg/dL. Her urine gives a strong purple ring with Rothera's test, Benedict's test remains blue and the glucose oxidase strip is negative. The most likely explanation is:

In hemolytic jaundice, the urine typically shows:

An 8-year-old boy had a sore throat 2 weeks ago. He now has puffy eyes, raised blood pressure and scanty smoky urine. Urine protein 1+, sediment shows many red cells and red cell casts. The most likely diagnosis is:

Benedict's test for reducing sugars in urine depends on the reduction of:

Colourless hexagonal plates in acidic urine point to which disorder?