Laboratory Science Urinalysis and Body Fluids 1 — Questions and Answers
Question 1: What is the normal specific gravity range for urine?
- 1.000–1.002
- 1.003–1.030 (Correct answer)
- 1.035–1.050
- 1.060–1.080
Correct answer: 1.003–1.030
Normal urine specific gravity ranges from 1.003–1.030, reflecting the kidney's concentrating ability; values closer to 1.010 indicate isosthenuria (loss of concentrating ability).
Question 2: Glucose detected on a urine dipstick is most commonly associated with which condition?
- Normal finding in adults
- Diabetes mellitus (blood glucose exceeding renal threshold ~180 mg/dL) (Correct answer)
- Urinary tract infection
- Kidney stones
Correct answer: Diabetes mellitus (blood glucose exceeding renal threshold ~180 mg/dL)
Glucosuria occurs when blood glucose exceeds the renal tubular reabsorption threshold (~180 mg/dL), spilling glucose into the urine, characteristic of poorly controlled diabetes.
Question 3: Which urine cast type indicates the most severe renal tubular damage?
- Hyaline casts
- Granular casts
- Waxy (broad) casts (Correct answer)
- RBC casts
Correct answer: Waxy (broad) casts
Waxy (broad) casts form from degenerated cellular casts in severely dilated tubules during end-stage renal disease; their presence indicates advanced, often irreversible renal failure.
Question 4: RBC casts in urine sediment are pathognomonic for which condition?
- Urinary tract infection
- Nephrotic syndrome
- Glomerulonephritis (Correct answer)
- Renal calculi
Correct answer: Glomerulonephritis
RBC casts form when red blood cells become entrapped in protein matrix within renal tubules, a finding pathognomonic for glomerulonephritis with glomerular inflammation.
Question 5: A positive nitrite test on a urine dipstick indicates:
- High protein levels
- Presence of nitrate-reducing bacteria (gram-negative bacteria) suggesting UTI (Correct answer)
- Ketone bodies
- Bilirubin in urine
Correct answer: Presence of nitrate-reducing bacteria (gram-negative bacteria) suggesting UTI
Gram-negative bacteria (like E. coli) reduce dietary nitrates to nitrites; a positive nitrite test suggests bacterial UTI, though false negatives occur with low-nitrate diets or non-reducing organisms.
Question 6: Which finding in cerebrospinal fluid (CSF) analysis is most consistent with bacterial meningitis?
- Clear fluid with lymphocytes and normal glucose
- Cloudy fluid with elevated neutrophils and decreased glucose (Correct answer)
- Xanthochromic fluid with RBCs
- Normal fluid with elevated protein only
Correct answer: Cloudy fluid with elevated neutrophils and decreased glucose
Bacterial meningitis typically produces cloudy CSF with neutrophilic pleocytosis, decreased glucose (bacteria consume it), and elevated protein from blood-brain barrier disruption.
Laboratory Science Urinalysis and Body Fluids 1
What is the normal specific gravity range for urine?