A 52-year-old man with type 2 diabetes is screened for kidney disease at a diabetes clinic. The laboratory reports the urine albumin-to-creatinine ratio (ACR) using KDIGO categories: A1 below 3 mg/mmol (30 mg/g), A2 3-30 mg/mmol, A3 above 30 mg/mmol. Albuminuria counts as persistent only when at least 2 of 3 early-morning specimens over 3-6 months are raised. Results: March, ACR 2.2 mg/mmol; May, ACR 11.5 mg/mmol, collected during a febrile illness with dysuria, positive nitrite and leukocyte esterase, and a culture growing more than 10^5 CFU/mL of Escherichia coli; August, ACR 2.6 mg/mmol, with no symptoms. His eGFR is 88 mL/min/1.73 m². What is the best interpretation?

Category A1; the May rise was transient

Category A3; the albuminuria is severe

Category A2; the albuminuria is persistent

Unclassified; a 24-hour urine is needed

A 6-year-old boy in Al Ain with known G6PD deficiency is brought in with pallor and dark urine 2 days after eating fava beans. Results: hemoglobin 68 g/L (6.8 g/dL; reference 115-145 g/L); plasma visibly pink; haptoglobin undetectable; serum total bilirubin 62 µmol/L (3.6 mg/dL), of which conjugated bilirubin is 5 µmol/L (0.3 mg/dL); CK normal. A fresh urine is sent for urinalysis, and the laboratory's urobilinogen reference is below 1.0 EU/dL (about 17 µmol/L). Which urinalysis result set fits his condition best?

Blood 3+, RBC 0-2/HPF, bilirubin negative, urobilinogen 4 EU/dL

Blood 3+, RBC 0-2/HPF, bilirubin 2+, urobilinogen 4 EU/dL

Blood 3+, RBC over 50/HPF, bilirubin negative, urobilinogen 0.2 EU/dL

Blood negative, RBC 0-2/HPF, bilirubin 3+, urobilinogen 0.2 EU/dL

A 42-year-old man is receiving intravenous benzylpenicillin, 24 million units a day, for streptococcal endocarditis. A urine collected 1 hour after a dose gives: SG 1.018, pH 6.0, protein pad negative, blood negative, glucose negative. A sulfosalicylic acid (SSA) test on the centrifuged supernatant shows 2+ turbidity. He has had no contrast imaging this admission and takes no other medicines. Serum protein electrophoresis is normal, the serum free light chain kappa/lambda ratio is within its reference interval, and the urine albumin-to-creatinine ratio is 1.5 mg/mmol (reference below 3 mg/mmol). What is the most likely cause of the SSA result?

High-dose penicillin in the urine

Albumin below the protein pad's limit

Free light chains missed by the pad

Iodinated contrast medium in the urine

Chemical examination: reagent strips and confirmatory tests

28 DOH Abu Dhabi (HAAD) lab licensing practice questions on Chemical examination: reagent strips and confirmatory tests, part of Urinalysis and Body Fluids. 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 · Hard
A 52-year-old man with type 2 diabetes is screened for kidney disease at a diabetes clinic. The laboratory reports the urine albumin-to-creatinine ratio (ACR) using KDIGO categories: A1 below 3 mg/mmol (30 mg/g), A2 3-30 mg/mmol, A3 above 30 mg/mmol. Albuminuria counts as persistent only when at least 2 of 3 early-morning specimens over 3-6 months are raised. Results: March, ACR 2.2 mg/mmol; May, ACR 11.5 mg/mmol, collected during a febrile illness with dysuria, positive nitrite and leukocyte esterase, and a culture growing more than 10^5 CFU/mL of Escherichia coli; August, ACR 2.6 mg/mmol, with no symptoms. His eGFR is 88 mL/min/1.73 m². What is the best interpretation?
1. ACategory A3; the albuminuria is severe
2. BCategory A1; the May rise was transient
3. CCategory A2; the albuminuria is persistent
4. DUnclassified; a 24-hour urine is needed
Show answerHide answer
Answer: B · Category A1; the May rise was transient
Urine albumin rises for a time with urinary tract infection, fever, heavy exercise, marked hyperglycemia, heart failure and menstruation, so a single raised ACR must be confirmed before it is acted on. Only the May specimen is raised, and it was collected during a febrile E. coli infection; the specimens before and after it are below 3 mg/mmol. Two of the three results are therefore normal, and he stays in category A1. Labelling him A2 or A3 from one value would wrongly diagnose diabetic kidney disease. He should continue yearly ACR screening, avoiding collection during infection.
- A: A3 needs an ACR above 30 mg/mmol, and the single raised value is 11.5 mg/mmol.
- C: A2 needs at least 2 of 3 raised specimens, and only one is raised.
- D: ACR on an early-morning urine is the recommended test; a 24-hour urine is not needed.
Question 2 · Hard
A 6-year-old boy in Al Ain with known G6PD deficiency is brought in with pallor and dark urine 2 days after eating fava beans. Results: hemoglobin 68 g/L (6.8 g/dL; reference 115-145 g/L); plasma visibly pink; haptoglobin undetectable; serum total bilirubin 62 µmol/L (3.6 mg/dL), of which conjugated bilirubin is 5 µmol/L (0.3 mg/dL); CK normal. A fresh urine is sent for urinalysis, and the laboratory's urobilinogen reference is below 1.0 EU/dL (about 17 µmol/L). Which urinalysis result set fits his condition best?
1. ABlood 3+, RBC 0-2/HPF, bilirubin 2+, urobilinogen 4 EU/dL
2. BBlood 3+, RBC over 50/HPF, bilirubin negative, urobilinogen 0.2 EU/dL
3. CBlood 3+, RBC 0-2/HPF, bilirubin negative, urobilinogen 4 EU/dL
4. DBlood negative, RBC 0-2/HPF, bilirubin 3+, urobilinogen 0.2 EU/dL
Show answerHide answer
Answer: C · Blood 3+, RBC 0-2/HPF, bilirubin negative, urobilinogen 4 EU/dL
Fava beans trigger acute intravascular hemolysis in G6PD deficiency; once haptoglobin is used up, free hemoglobin passes into the urine and makes the blood pad positive without intact red cells. The extra bilirubin from hemolysis is unconjugated and bound to albumin, so it is not filtered and the bilirubin pad stays negative, as the low conjugated fraction here predicts. More bilirubin reaches the gut, so more urobilinogen is formed, reabsorbed and excreted in the urine. Many red cells would mean bleeding in the urinary tract, and a positive bilirubin pad with a low urobilinogen is the pattern of biliary obstruction. This urine pattern points to intravascular hemolysis rather than urinary tract bleeding.
- A: Unconjugated bilirubin is bound to albumin and does not pass into the urine.
- B: Many intact red cells mean bleeding in the urinary tract, not hemoglobinuria.
- D: This is the pattern of biliary obstruction; free hemoglobin would make the blood pad positive.
Question 3 · Hard
A 42-year-old man is receiving intravenous benzylpenicillin, 24 million units a day, for streptococcal endocarditis. A urine collected 1 hour after a dose gives: SG 1.018, pH 6.0, protein pad negative, blood negative, glucose negative. A sulfosalicylic acid (SSA) test on the centrifuged supernatant shows 2+ turbidity. He has had no contrast imaging this admission and takes no other medicines. Serum protein electrophoresis is normal, the serum free light chain kappa/lambda ratio is within its reference interval, and the urine albumin-to-creatinine ratio is 1.5 mg/mmol (reference below 3 mg/mmol). What is the most likely cause of the SSA result?
1. AAlbumin below the protein pad's limit
2. BFree light chains missed by the pad
3. CIodinated contrast medium in the urine
4. DHigh-dose penicillin in the urine
Show answerHide answer
Answer: D · High-dose penicillin in the urine
SSA precipitates all proteins, but it is also turned cloudy by some drugs that come out of solution in strong acid, including large doses of penicillins and cephalosporins, sulfonamides, tolbutamide and radiographic contrast media. Here the protein pad and the albumin-to-creatinine ratio are both normal, so albumin is not raised. The normal free light chain ratio and electrophoresis make light chain (Bence Jones) proteinuria unlikely, and no contrast has been given. That leaves the very high urine penicillin level, sampled soon after a dose. Report the SSA result with a comment on the likely drug effect, or repeat it on a urine collected just before the next dose.
- A: The albumin-to-creatinine ratio is normal, so there is no excess albumin for SSA to detect.
- B: Light chain proteinuria is unlikely with a normal free light chain ratio and normal electrophoresis.
- C: No contrast medium has been given during this admission.
Question 4 · Easy
Which two pads on the strip shown give the most direct evidence of a bacterial urinary tract infection?
Figure: MedExams
1. ANitrite and leukocyte esterase
2. BKetones and blood
3. CBlood and protein
4. DpH and specific gravity
Show answerHide answer
Answer: A · Nitrite and leukocyte esterase
The nitrite pad turns positive when gram-negative bacteria, mainly Enterobacterales, reduce urinary nitrate to nitrite. The leukocyte esterase pad detects an enzyme released by neutrophils, so it signals pyuria. Together they strongly suggest infection, and the urine is examined microscopically and cultured. Trace blood and protein are common, nonspecific findings in infection, and trace ketones usually reflect fasting.
- B: Ketones come from fat metabolism, for example during fasting, not from infection.
- C: Trace blood and protein can accompany infection but have many other causes.
- D: A pH of 6.0 and a specific gravity of 1.020 are both within normal limits.
Question 5 · Medium
Reagent strip results for four jaundiced adults are shown. Whose results fit complete obstruction of the common bile duct?
Figure: MedExams
1. APatient A
2. BPatient C
3. CPatient D
4. DPatient B
Show answerHide answer
Answer: B · Patient C
When bile cannot reach the gut, conjugated bilirubin backs up into the blood and is filtered into the urine, so the bilirubin pad is strongly positive, as in patient C. With no bilirubin entering the intestine, no urobilinogen is formed, and because the strip cannot report a value below its lowest block, a normal-looking 3.2 µmol/L fits. Patient A (no bilirubin, very high urobilinogen) fits hemolysis, and patient B (bilirubin with a raised urobilinogen) fits hepatocellular disease. Pale stools and a positive Ictotest support obstruction.
- A: No urine bilirubin with a very high urobilinogen fits hemolytic (prehepatic) jaundice.
- C: A negative bilirubin and normal urobilinogen in jaundice fit an unconjugated hyperbilirubinemia such as Gilbert syndrome.
- D: Bilirubin with a raised urobilinogen fits hepatocellular disease, in which some bile still reaches the gut.
Question 6 · Medium
Why can the reagent strip nitrite test be negative in a urinary tract infection?
1. AA high urine pH interfered with the nitrite reagent pad
2. BNon-nitrate-reducing organism, or too short a bladder time
3. CMany white cells in the urine blocked the nitrite reaction
4. DThe sample was a concentrated first morning specimen
Answer and explanation in LearnFree account
Question 7 · Hard
Which ketone body does the nitroprusside reagent strip pad mainly detect?
1. AAcetoacetic acid
2. BAll three ketone bodies equally
3. CGlucose
4. DBeta-hydroxybutyrate
Answer and explanation in LearnFree account
Question 8 · Easy
The sulfosalicylic acid (SSA) test detects urine protein by:
1. AAntibody binding to albumin
2. BCopper reduction in alkaline solution
3. CThe protein error of a pH indicator
4. DAcid precipitation, read as turbidity
Answer and explanation in LearnFree account
Question 9 · Easy
The reagent strip nitrite test is based on the:
1. AGriess reaction
2. BJaffe reaction
3. CEhrlich reaction
4. DBenedict reaction
Answer and explanation in LearnFree account
Question 10 · Medium
The Hoesch test adds a few drops of urine to Ehrlich's reagent in strong hydrochloric acid. What does the high acidity achieve?
1. AIt converts porphobilinogen into porphyrins
2. BIt extracts porphobilinogen into a solvent
3. CIt makes the test quantitative for PBG
4. DIt largely stops urobilinogen from reacting
Answer and explanation in LearnFree account
Question 11 · Hard
A febrile patient with chemotherapy-induced neutropenia (neutrophils 0.1 x 10^9/L) has a fresh catheter urine: nitrite positive, leukocyte esterase negative at 2 minutes, no white cells seen and many bacteria. Culture grows more than 10^5 CFU/mL of Escherichia coli. Why is the esterase negative?
1. AThe pad was read too early
2. BToo few neutrophils reach the urine
3. CE. coli destroys leukocyte esterase
4. DNitrite inhibits the esterase reaction
Answer and explanation in LearnFree account
Question 12 · Medium
In a urine left standing at room temperature, the urobilinogen result falls because urobilinogen is:
1. ASplit by bacterial urease
2. BPrecipitated with urates
3. COxidized to urobilin
4. DConverted to bilirubin
Answer and explanation in LearnFree account
Question 13 · Hard
A dark urine gives an unusual orange-tan color on the bilirubin pad, which the analyzer reports as 'small'. An Ictotest done at once on the same urine is negative, and the serum bilirubin is normal. The best interpretation is:
1. AThe pad detected unconjugated bilirubin
2. BBilirubin is below the Ictotest detection limit
3. CA urine pigment gave a false-positive pad
4. DLight destroyed the bilirubin before the Ictotest
Answer and explanation in LearnFree account
Question 14 · Medium
Which urine is most likely to give a false-positive reagent strip protein result?
1. AA urine high in ascorbic acid
2. BA very dilute urine
3. CA highly buffered alkaline urine
4. DA urine with heavy glycosuria
Answer and explanation in LearnFree account
Question 15 · Hard
A urine that stood for 3 hours at room temperature has specific gravity 1.004 and pH 8.0. Leukocyte esterase is moderate, but only 0-2 white cells/HPF are seen. What best explains the difference?
1. ABacteria in the urine made the esterase
2. BSquamous cells reacted on the esterase pad
3. CWhite cells lysed, but their esterase remained
4. DLymphocytes reacted on the esterase pad
Answer and explanation in LearnFree account
Question 16 · Hard
A woman with poorly controlled diabetes has dysuria. Urine: glucose 4+ (over 111 mmol/L, 2,000 mg/dL), refractometer specific gravity 1.040, leukocyte esterase negative at 2 minutes; the sediment shows 20-25 white cells/HPF, mostly neutrophils. She takes no vitamin C or antibiotics. What best explains the negative esterase?
1. AThe esterase was lost when the cells lysed
2. BThe white cells seen are lymphocytes, not neutrophils
3. CHigh glucose and specific gravity inhibiting the pad
4. DThe pad needs bacteria as well as white cells
Answer and explanation in LearnFree account
Question 17 · Hard
A urine collected in a sterile laboratory cup has a glucose pad reading of 5.5 mmol/L (100 mg/dL), and strip QC is acceptable. A 5-drop Clinitest done on the same urine at the same time is negative. What is the best explanation?
1. AClinitest is less sensitive than the glucose pad
2. BA non-glucose sugar is present in the urine
3. CBacteria used up the glucose before the Clinitest
4. DAscorbic acid inhibited the Clinitest reaction
Answer and explanation in LearnFree account
Question 18 · Medium
Before an SSA test is set up on a cloudy urine, the urine should be:
1. ADiluted 1 in 10 with saline
2. BWarmed to 60 °C for 10 minutes
3. CCentrifuged, and the supernatant tested
4. DMade alkaline with sodium hydroxide
Answer and explanation in LearnFree account
Question 19 · Medium
Excess urine is left on a strip held upright, and acid buffer from the protein pad runs onto the pH pad. The pH result will most likely be:
1. AFalsely low (more acid)
2. BFalsely high (more alkaline)
3. CUnreadable, from mixed colors
4. DUnchanged, as the pad is buffered
Answer and explanation in LearnFree account
Question 20 · Hard
At the start of a shift, the positive control gives negative glucose, blood and leukocyte esterase results on strips from a bottle found uncapped overnight. The negative control reads correctly. What should be done?
1. ARead the pads later to allow a slower color change
2. BDiscard the bottle and repeat QC with a closed one
3. CReport patients with a comment on the QC failure
4. DRepeat the positive control with the same bottle
Answer and explanation in LearnFree account
Question 21 · Medium
On a strip read by eye, the nitrite pad shows a faint but even pink color. How should it be reported?
1. ANegative, as only deep pink counts
2. BPositive, with a low bacterial count
3. CPositive, as any even pink counts
4. DTrace, pending a repeat strip
Answer and explanation in LearnFree account
Question 22 · Easy
Ehrlich's reagent, which reacts with urobilinogen and porphobilinogen, contains:
1. ASulfosalicylic acid
2. Bp-Dimethylaminobenzaldehyde
3. CSodium nitroprusside
4. DTetrabromphenol blue
Answer and explanation in LearnFree account
Question 23 · Hard
A random urine from a man with suspected early kidney disease has specific gravity 1.003 and a trace protein on the strip. Which follow-up best shows whether his protein loss is significant?
1. AA refractometer specific gravity
2. BA urine protein-to-creatinine ratio
3. CA repeat strip on the same urine
4. DAn SSA test on the same urine
Answer and explanation in LearnFree account
Question 24 · Easy
The reagent strip bilirubin pad detects conjugated bilirubin by coupling it with:
1. ASodium nitroprusside
2. BTetrabromphenol blue
3. CA diazonium salt in acid
4. DGlucose oxidase
Answer and explanation in LearnFree account
Question 25 · Hard
A red-brown urine has a blood pad of 3+ and 0-2 RBC/HPF, and no plasma sample is available. The urine is brought to 80% saturation with ammonium sulfate and filtered; the filtrate is still red-brown and blood-pad positive. The pigment is most likely:
1. AIntact red cells
2. BMyoglobin
3. CHemoglobin
4. DPorphobilinogen
Answer and explanation in LearnFree account

3 more Chemical examination: reagent strips and confirmatory tests questions

Answer them one by one, keep your score and see your weak topics in Learn. Signed-out visitors try 25 per exam; sign in with Google to see them all.

Study Urinalysis and Body Fluids

Chemical examination: reagent strips and confirmatory tests

Which two pads on the strip shown give the most direct evidence of a bacterial urinary tract infection?

Reagent strip results for four jaundiced adults are shown. Whose results fit complete obstruction of the common bile duct?

Why can the reagent strip nitrite test be negative in a urinary tract infection?

Which ketone body does the nitroprusside reagent strip pad mainly detect?

The sulfosalicylic acid (SSA) test detects urine protein by:

The reagent strip nitrite test is based on the:

The Hoesch test adds a few drops of urine to Ehrlich's reagent in strong hydrochloric acid. What does the high acidity achieve?

A febrile patient with chemotherapy-induced neutropenia (neutrophils 0.1 x 10^9/L) has a fresh catheter urine: nitrite positive, leukocyte esterase negative at 2 minutes, no white cells seen and many bacteria. Culture grows more than 10^5 CFU/mL of Escherichia coli. Why is the esterase negative?

In a urine left standing at room temperature, the urobilinogen result falls because urobilinogen is:

A dark urine gives an unusual orange-tan color on the bilirubin pad, which the analyzer reports as 'small'. An Ictotest done at once on the same urine is negative, and the serum bilirubin is normal. The best interpretation is:

Which urine is most likely to give a false-positive reagent strip protein result?

A urine that stood for 3 hours at room temperature has specific gravity 1.004 and pH 8.0. Leukocyte esterase is moderate, but only 0-2 white cells/HPF are seen. What best explains the difference?

A urine collected in a sterile laboratory cup has a glucose pad reading of 5.5 mmol/L (100 mg/dL), and strip QC is acceptable. A 5-drop Clinitest done on the same urine at the same time is negative. What is the best explanation?

Before an SSA test is set up on a cloudy urine, the urine should be:

Excess urine is left on a strip held upright, and acid buffer from the protein pad runs onto the pH pad. The pH result will most likely be:

At the start of a shift, the positive control gives negative glucose, blood and leukocyte esterase results on strips from a bottle found uncapped overnight. The negative control reads correctly. What should be done?

On a strip read by eye, the nitrite pad shows a faint but even pink color. How should it be reported?

Ehrlich's reagent, which reacts with urobilinogen and porphobilinogen, contains:

A random urine from a man with suspected early kidney disease has specific gravity 1.003 and a trace protein on the strip. Which follow-up best shows whether his protein loss is significant?

The reagent strip bilirubin pad detects conjugated bilirubin by coupling it with:

A red-brown urine has a blood pad of 3+ and 0-2 RBC/HPF, and no plasma sample is available. The urine is brought to 80% saturation with ammonium sulfate and filtered; the filtrate is still red-brown and blood-pad positive. The pigment is most likely: