MLPAO Urinalysis and Body Fluids Fundamentals

Question 1

What is the preferred urine specimen for routine urinalysis?

Accepted Answer

First morning midstream clean-catch specimen

Answer

The first morning midstream clean-catch specimen is preferred for routine urinalysis because it is the most concentrated, maximizing the detection of chemical constituents and formed elements. Midstream collection reduces contamination from urethral flora and epithelial cells. Proper patient instruction is essential for specimen quality.

Question 2

What are the three components of a complete urinalysis?

Accepted Answer

Physical examination (colour, clarity, specific gravity), chemical examination (dipstick), and microscopic examination (sediment)

Answer

A complete urinalysis includes: 1) Physical examination (colour, clarity/turbidity, specific gravity, odour), 2) Chemical examination (reagent strip/dipstick testing for pH, protein, glucose, ketones, blood, bilirubin, urobilinogen, nitrite, leukocyte esterase, and specific gravity), and 3) Microscopic examination (centrifuged sediment for cells, casts, crystals, and organisms).

Question 3

What does a positive nitrite test on a urine dipstick indicate?

Accepted Answer

Presence of bacteria (particularly gram-negative) that reduce dietary nitrate to nitrite

Answer

A positive nitrite indicates the presence of bacteria (mainly gram-negative Enterobacterales like E. coli) that convert dietary nitrate to nitrite via bacterial nitrate reductase. The test requires the urine to have been in the bladder for at least 4 hours. Not all bacteria produce nitrite (e.g., enterococci, staphylococci), so a negative nitrite does not rule out UTI.

Question 4

What is the principle of the leukocyte esterase test on the dipstick?

Accepted Answer

It detects an enzyme released from lysed granulocytes (neutrophils), indicating pyuria

Answer

The leukocyte esterase test detects esterase enzyme released from lysed neutrophils. It indicates pyuria (white blood cells in urine) and suggests inflammation or infection. It can be positive even when intact WBCs are not seen microscopically because it detects enzyme from lysed cells. Combined with nitrite, it has good negative predictive value for UTI.

Question 5

Which urine cast is most indicative of glomerulonephritis?

Accepted Answer

Red blood cell cast

Answer

Red blood cell (RBC) casts are virtually pathognomonic for glomerulonephritis because they indicate bleeding within the nephron. RBCs trapped in Tamm-Horsfall protein within the tubular lumen form these casts. Their presence localizes hematuria to the kidney (glomerular origin) rather than the lower urinary tract.

MLPAO - Medical Laboratory Professionals Association of Ontario Practice Test

MLPAO - Medical Laboratory Professionals Association of Ontario Practice Test

MLPAO Urinalysis and Body Fluids Fundamentals