Laboratory Science Urinalysis and Body Fluids

Question 1

What is the normal specific gravity range for urine?

Accepted Answer

1.003–1.030

Answer

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?

Accepted Answer

Diabetes mellitus (blood glucose exceeding renal threshold ~180 mg/dL)

Answer

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?

Accepted Answer

Waxy (broad) casts

Answer

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?

Accepted Answer

Glomerulonephritis

Answer

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:

Accepted Answer

Presence of nitrate-reducing bacteria (gram-negative bacteria) suggesting UTI

Answer

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.

Laboratory Science Practice Test

Laboratory Science Practice Test

Laboratory Science Urinalysis and Body Fluids