7.1 Routine Physical and Biochemical Urine Tests

Question 1

Which statement regarding renal function is true?

Answer 1

Glomeruli are far more permeable to H2O and salt compared with other capillaries

Question 2

Which statement regarding normal salt and H2O handling by the nephron is correct?

Answer 2

The thick ascending limb of the tubule is highly permeable to salt but not H2O

Question 3

Which statement concerning renal tubular function is true?

Answer 3

In salt deprivation, the kidneys will conserve sodium at the expense of potassium

Question 4

Which of the following is inappropriate when collecting urine for routine bacteriologic culture?

Answer 4

The sample may be held at 2°C to 8°C for up to 48 hours prior to plating

Question 5

Which statement about sample collection for routine urinalysis is true?

Answer 5

Samples may be stored at room temperature for up to 2 hours

Question 6

Which urine color is correlated correctly with the pigment-producing substance?

Answer 6

Deep yellow urine and yellow foam with bilirubin

Question 7

Which of the following substances will cause urine to produce red fluorescence when examined under an ultraviolet lamp (360 nm)?

Answer 7

Coproporphyrin

Question 8

Which of the following conditions is associated with normal urine color but produces red fluorescence when urine is examined with an ultraviolet (Wood) lamp?

Answer 8

Lead poisoning

Question 9

Which statement regarding porphyria is accurate?

Answer 9

Serum, urine, and fecal tests may be needed for diagnosis

Question 10

Which is the most common form of porphyria?

Answer 10

Porphyria cutanea tarda

Question 11

Which of the following methods is the least sensitive and specific for measuring PBG in urine?

Answer 11

Watson-Schwartz test

Question 12

A brown or black pigment in urine can be caused by:

Answer 12

Melanin

Question 13

Urine that is dark red or port wine-colored may be caused by:

Answer 13

Porphyria cutanea tarda

Question 14

Which of the following tests is affected least by standing or improperly stored urine?

Answer 14

Protein

Question 15

Which one of the following characteristics would be a reason for performing a microscopic examination of urinary sediment?

Answer 15

Turbidity

Question 16

Which of the following is appropriate when collecting a 24-hour urine sample for metanephrines?

Answer 16

All urine should be collected in a single container that is kept refrigerated

Question 17

Urine production of less than 400 mL/day is:

Answer 17

Defined as oliguria

Question 18

Which of the following contributes to SG, but not to osmolality?

Answer 18

Protein

Question 19

Urine with an SG consistently between 1.002 and 1.003 indicates:

Answer 19

Diabetes insipidus

Question 20

In which of the following conditions is the urine SG likely to be below 1.025?

Answer 20

Chronic renal failure

Question 21

Which statement regarding methods for measuring SG is true?

Answer 21

Colorimetric SG readings are falsely low when pH is alkaline

Question 22

What is the principle of the colorimetric reagent strip determination of SG in urine?

Answer 22

Ionic strength alters the pKa of a polyelectrolyte

Question 23

Which statement regarding urine pH is true?

Answer 23

Contamination should be suspected if urine pH is less than 4.5

Question 24

In renal tubular acidosis, the pH of urine is:

Answer 24

Consistently alkaline

Question 25

The normal daily urine output for an adult is approximately:

Answer 25

0.6 to 1.6 L

Question 26

The SG of the filtrate in the Bowman space is approximately:

Answer 26

1.008 to 1.010

Question 27

A patient with partially compensated respiratory alkalosis would have a urine pH of:

Answer 27

7.5 to 8.5

Question 28

Which of the following is most likely to cause a false-positive result on the dry reagent strip test for urinary protein?

Answer 28

Highly buffered alkaline urine

Question 29

When testing for urinary protein with sulfosalicylic acid (SSA), which condition may produce a false-positive result?

Answer 29

The presence of x-ray contrast media

Question 30

A discrepancy between the urine SG determined by measuring refractive index and urine osmolality would be most likely to occur:

Answer 30

After intravenous pyelography (IVP)

Question 31

Which of the following is likely to result in a false-negative dry reagent strip test for proteinuria?

Answer 31

Bence-Jones protein

Question 32

Daily loss of protein in urine normally does not exceed:

Answer 32

150 mg

Question 33

Which of the following is least likely to cause a false-positive result on turbidimetric protein tests?

Answer 33

Ascorbic acid

Question 34

Which statement best describes the clinical utility of tests for microalbuminuria?

Answer 34

Testing may detect early renal involvement in diabetes mellitus

Question 35

Dry reagent strip tests for microalbuminuria that compare albumin to creatinine determine the creatinine concentration based on which principle?

Answer 35

Formation of a Cu+2–creatinine complex

Question 36

Which of the following conditions is least likely to be detected by dry reagent strip tests for proteinuria?

Answer 36

Renal tubular proteinuria

Question 37

The normal renal threshold for glucose is:

Answer 37

165 to 180 mg/dL

Question 38

In which of the following conditions is glycosuria most likely?

Answer 38

Pregnancy

Question 39

In addition to ascorbate, the glucose oxidase reaction may be inhibited by which substance?

Answer 39

Acetoacetic acid (AAA)

Question 40

A positive glucose oxidase test and a negative test for reducing sugars indicates:

Answer 40

True glycosuria

Question 41

A negative glucose oxidase test and a positive test for reducing sugars in urine indicates:

Answer 41

The presence of a nonglucose reducing sugar, such as galactose

Question 42

In what condition may urinary ketone tests underestimate ketosis?

Answer 42

Acidosis

Question 43

AAA is detected in urine by reaction with:

Answer 43

Sodium nitroprusside

Question 44

Nondiabetic ketonuria can occur in all of the following except: A. Pregnancy B. Renal failure C. Starvation D. Lactate acidosis

Answer 44

Renal failure

Question 45

Which of the following statements regarding the classic nitroprusside reaction for ketones is true?

Answer 45

It may be falsely positive in phenylketonuria

Question 46

Hemoglobin in urine can be differentiated from myoglobin by using:

Answer 46

80% ammonium sulfate to precipitate hemoglobin

Question 47

Which of the following conditions is associated with a negative blood test result and an increase in urine urobilinogen?

Answer 47

Extravascular hemolytic anemia

Question 48

Which statement about the dry reagent strip blood test is true?

Answer 48

Abnormal color may be absent from the urine when the reaction is positive

Question 49

A moderately positive result on the blood test and trace protein test are seen on the dry reagent strip, and 11 to 20 RBCs/HPF are seen in the microscopic examination. These results are most likely caused by which of the following?

Answer 49

Recent urinary tract catheterization

Question 50

Which of the following results are discrepant?

Answer 50

Negative blood, but 6 to 10 RBCs/HPF

Question 51

Which of the following statements regarding the dry reagent strip test for bilirubin is true?

Answer 51

The test detects only conjugated bilirubin

Question 52

Which of the following reagents is used to detect urobilinogen in urine?

Answer 52

p-Dimethylaminobenzaldehyde

Question 53

Which of the following statements regarding urinary urobilinogen is true?

Answer 53

Dry reagent strip tests do not detect decreased levels

Question 54

Which of the following statements regarding the test for nitrite in urine is true?

Answer 54

The test is dependent on adequate dietary nitrate content

Question 55

Which statement about the dry reagent strip test for leukocytes is true?

Answer 55

The reaction is based on the hydrolysis of substrate by WBC esterases

Question 56

Which of the following statements about creatinine clearance is correct?

Answer 56

Creatinine clearance is dependent on lean body mass

Question 57

A male patient’s eGFR is 75 mL/min. This indicates:

Answer 57

Reduced glomerular filtration without uremia

Question 58

Which of the following substances can be used to calculate eGFR?

Answer 58

Cystatin C

Question 59

Which statement regarding urea is true?

Answer 59

Urea is 100% filtered by the glomeruli

Question 60

Given the following data, calculate the creatinine clearance: Serum creatinine = 1.2 mg/Dl Urine creatinine = 100 mg/dL Urine volume = 1.4 L/day Body surface area = 1.80 m2

Answer 60

78 mL/min U ÷ P × V × 1.73/A, where U = urine creatinine (mg/dL), P = plasma creatinine (mg/dL), V = urine volume (mL/min), and 1.73 = mean body surface area (m2)