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BOC review-Harr 5th ed > UA 7.1 Routine Physical and Biochemical Urine Tests > Flashcards

UA 7.1 Routine Physical and Biochemical Urine Tests Flashcards

1
Q
  1. Which statement regarding renal function is true?

A. Glomeruli are far more permeable to H2O and salt compared with other capillaries
B. The collecting tubule reabsorbs sodium and secretes potassium in response to antidiuretic hormone (ADH)
C. The collecting tubule is permeable to H2O only in the presence of aldosterone
D. The thick ascending limb is highly permeable to and urea

A

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

The formation of plasma ultrafiltrate depends on high hydrostatic pressure and permeability of the glomeruli. Aldosterone is released when afferent arterial pressure falls, and ADH is released when plasma osmolality becomes too high. The collecting tubule reabsorbs sodium and secretes potassium in response to aldosterone and is permeable to H2O only in the presence of ADH. The thick ascending limb is permeable to salt, but not to H2O or urea.

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2
Q
  1. Which statement regarding normal salt and H2O handling by the nephron is correct?

A. The thick ascending limb of the tubule is highly permeable to salt but not H2O
B. The stimulus for ADH release is low arterial pressure in the afferent arteriole
C. The descending limb of the tubule is impermeable to urea but highly permeable to salt
D. Renin is released in response to high plasma osmolality

A

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

The tubules are able to concentrate the filtrate because the descending limb is highly permeable to H2O and urea, but not to salt, and the ascending limb is permeable to salt. Salt leaving the thick ascending limb creates a hypertonic interstitium that forces H2O from the descending limb. Renin is released in response to low hydrostatic pressure in the afferent arteriole, which stimulates the juxtaglomerular cells. ADH is released by the posterior pituitary in response to high plasma osmolality.

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3
Q
  1. Which statement concerning renal tubular function is true?

A. In salt deprivation, the kidneys will conserve sodium at the expense of potassium
B. Potassium is not excreted when serum concentration is less than 3.5 mmol/L
C. No substance can be excreted into urine at a rate that exceeds the glomerular filtration rate (GFR)
D. When tubular function is lost, the specific gravity (SG) of urine will be below 1.005

A

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

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4
Q
  1. Which of the following is inappropriate when collecting urine for routine bacteriologic culture?

A. The container must be sterile
B. The midstream void technique must be used
C. The collected sample must be plated within 2 hours unless refrigerated
D. The sample may be held at 2°C to 8°C for up to 48 hours prior to plating

A

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

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5
Q
  1. Which statement about sample collection for routine urinalysis is true?

A. Preservative tablets should be used for collecting random urine specimens
B. Containers may be washed and reused if rinsed in deionized H2O
C. Samples may be stored at room temperature for up to 2 hours
D. A midday sample is preferred when renal disease is suspected

A

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

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6
Q
  1. Which urine color is correlated correctly with the pigment-producing substance?

A. Smoky red urine with homogentisic acid
B. Dark amber urine with myoglobin
C. Deep yellow urine and yellow foam with bilirubin
D. Red-brown urine with biliverdin

A

C. Deep yellow urine and yellow foam with bilirubin

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7
Q
  1. Which of the following substances will cause urine to produce red fluorescence when examined under an ultraviolet lamp (360 nm)?

A. Myoglobin
B. Porphobilinogen (PBG)
C. Urobilin
D. Coproporphyrin

A

D. Coproporphyrin

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8
Q
  1. Which of the following conditions is associated with normal urine color but produces red fluorescence when urine is examined with an ultraviolet (Wood) lamp?

A. Acute intermittent porphyria
B. Lead poisoning
C. Erythropoietic porphyria
D. Porphyria cutanea tarda

A

B. Lead poisoning

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9
Q
  1. Which statement regarding porphyria is accurate?

A. Porphyria is exclusively inherited
B. All types cause an increase in urinary porphyrins
C. All types are associated with anemia
D. Serum, urine, and fecal tests may be needed for diagnosis

A

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

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10
Q
  1. Which is the most common form of porphyria?

A. Erythropoietic porphyria
B. Acute intermittent porphyria
C. Variegate porphyria
D. Porphyria cutanea tarda

A

D. Porphyria cutanea tarda

Porphyria is a rare condition, although most of the inherited forms are autosomal dominant. Porphyria cutanea tarda results from a deficiency of uroporphyrinogen decarboxylase, and hence, the carboxylated forms of uroporphyrin accumulate in plasma and spill into urine. The enzyme in hepatocytes is susceptible to drugs, alcohol, and hepatitis, which trigger the disease. The disease usually appears in middle-aged adults, the majority of whom have hepatitis C infection. The uroporphyrins are highly fluorescent and may cause port wine–colored urine. Affected persons present with skin blisters and skin burns if they have been exposed to sunlight.

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11
Q
  1. Which of the following methods is the least sensitive and specific for measuring PBG in urine?

A. Watson-Schwartz test
B. LC-MS
C. Ion exchange chromatography–Ehrlich reaction
D. Isotope dilution–MS

A

A. Watson-Schwartz test

The Watson-Schwartz test is a qualitative screening test for PBG and is based on the principle that dietary indole compounds and urobilinogen can be separated from PBG by extraction.

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12
Q
  1. A brown or black pigment in urine can be caused by:

A. Gantrisin (pyridium)
B. Phenolsulfonphthalein (PSP)
C. Rifampin
D. Melanin

A

D. Melanin

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13
Q
  1. Urine that is dark red or port wine-colored may be caused by:

A. Lead poisoning
B. Porphyria cutanea tarda
C. Alkaptonuria
D. Hemolytic anemia

A

B. Porphyria cutanea tarda

Porphyria cutanea tarda and erythropoietic porphyria produce sufficient uroporphyrins to cause dark red urine. Acute intermittent porphyria produces large amounts of PBG, which may be oxidized to porphobilin, turning the urine orange to orange-brown.

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14
Q
  1. Which of the following tests is affected least by standing or improperly stored urine?

A. Glucose
B. Protein
C. pH
D. Bilirubin

A

B. Protein

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15
Q
  1. Which one of the following characteristics would be a reason for performing a microscopic examination of urinary sediment?

A. High volume
B. Color intensity
C. Turbidity
D. Specimen from a Foley catheter

A

C. Turbidity

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16
Q
  1. Which of the following is appropriate when collecting a 24-hour urine sample for metanephrines?

A. Urine in the bladder is voided at the start of the test and added to the collection container
B. At 24 hours, any urine in the bladder is voided and discarded
C. All urine should be collected in a single container that is kept refrigerated
D. Ten milliliters of 1N sodium hydroxide should be added to the container before collection

A

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

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17
Q
  1. Urine production of less than 400 mL/day is:

A. Consistent with normal renal function and H2O balance
B. Termed isosthenuria
C. Defined as oliguria
D. Associated with diabetes mellitus

A

C. Defined as oliguria

Normal daily urine excretion is usually 600 to 1,600 mL/day. Isosthenuria refers to urine of constant SG of 1.010, which is the SG of the glomerular filtrate. Glycosuria causes retention of H2O within the tubule, resulting in dehydration and polyuria, rather than oliguria.

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18
Q
  1. Which of the following contributes to SG, but not to osmolality?

A. Protein
B. Salt
C. Urea
D. Glucose

A

A. Protein

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19
Q
  1. Urine with an SG consistently between 1.002 and 1.003 indicates:

A. Acute glomerulonephritis
B. Renal tubular failure
C. Diabetes insipidus
D. Addison disease

A

C. Diabetes insipidus

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20
Q
  1. In which of the following conditions is the urine SG likely to be below 1.025?

A. Diabetes mellitus
B. Drug overdose
C. Chronic renal failure
D. Prerenal failure

A

C. Chronic renal failure

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21
Q
  1. Which statement regarding methods for measuring SG is true?

A. Refractometry is the most accurate way to determine dissolved solute concentration
B. Colorimetric SG test results are falsely elevated when a large quantity of glucose is present
C. Colorimetric SG readings are falsely low when pH is alkaline
D. Refractometry should be performed before the urine is centrifuged

A

C. Colorimetric SG readings are falsely low when pH is alkaline

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22
Q
  1. What is the principle of the colorimetric reagent strip determination of SG in urine?

A. Ionic strength alters the pKa of a polyelectrolyte
B. Sodium and other cations are chelated by a ligand that changes color
C. Anions displace a pH indicator from a mordant, making it water soluble
D. Ionized solutes catalyze oxidation of an azo dye

A

A. Ionic strength alters the pKa of a polyelectrolyte

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23
Q
  1. Which statement regarding urine pH is true?

A. A high-protein diet promotes an alkaline urine pH
B. pH tends to decrease as urine is stored
C. Contamination should be suspected if urine pH is less than 4.5
D. Bacteriuria is most often associated with a low urine pH

A

C. Contamination should be suspected if urine pH is less than 4.5

Bacteriuria is usually associated with an alkaline pH caused by the production of ammonia from urea. Extended storage may result in loss of volatile acids, causing increased pH. A high-protein diet promotes excretion of inorganic acids. The tubular maximum for hydrogen ion secretion occurs when urine pH reaches 4.5, the lowest urinary pH that the kidneys can produce.

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24
Q
  1. In renal tubular acidosis, the pH of urine is:

A. Consistently acid
B. Consistently alkaline
C. Neutral
D. Variable, depending on diet

A

B. Consistently alkaline

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25
Q
  1. The normal daily urine output for an adult is approximately:

A. 0.2 to 0.5 L
B. 0.6 to 1.6 L
C. 2.7 to 3.0 L
D. 3.2 to 3.5 L

A

B. 0.6 to 1.6 L

26
Q
  1. The SG of the filtrate in the Bowman space is approximately:

A. 1.000 to 1.002
B. 1.004 to 1.006
C. 1.008 to 1.010
D. 1.012 to 1.014

A

C. 1.008 to 1.010

27
Q
  1. A patient with partially compensated respiratory alkalosis would have a urine pH of:

A. 4.5 to 5.5
B. 5.5 to 6.5
C. 6.5 to 7.5
D. 7.5 to 8.5

A

D. 7.5 to 8.5

28
Q
  1. Which of the following is most likely to cause a false-positive result on the dry reagent strip test for urinary protein?

A. Urine of high SG
B. Highly buffered alkaline urine
C. Bence-Jones protein
D. Salicylates

A

B. Highly buffered alkaline urine

29
Q
  1. When testing for urinary protein with sulfosalicylic acid (SSA), which condition may produce a false-positive result?

A. Highly buffered alkaline urine
B. The presence of x-ray contrast media
C. Increased urinary SG
D. The presence of red blood cells (RBCs)

A

B. The presence of x-ray contrast media

30
Q
  1. A discrepancy between the urine SG determined by measuring refractive index and urine osmolality would be most likely to occur:

A. After catheterization of the urinary tract
B. In diabetes mellitus
C. After intravenous pyelography (IVP)
D. In uremia

A

C. After intravenous pyelography (IVP)

31
Q
  1. Which of the following is likely to result in a false-negative dry reagent strip test for proteinuria?

A. Penicillin
B. Aspirin
C. Amorphous phosphates
D. Bence-Jones protein

A

D. Bence-Jones protein

32
Q
  1. Daily loss of protein in urine normally does not exceed:

A. 30 mg
B. 50 mg
C. 100 mg
D. 150 mg

A

D. 150 mg

33
Q
  1. Which of the following is least likely to cause a false-positive result on turbidimetric protein tests?

A. Tolbutamide
B. X-ray contrast media
C. Penicillin or sulfa antibiotics
D. Ascorbic acid

A

D. Ascorbic acid

34
Q
  1. Which statement best describes the clinical utility of tests for microalbuminuria?

A. Testing may detect early renal involvement in diabetes mellitus
B. Microalbuminuria refers to a specific subfraction of albumin found only in persons with diabetic nephropathy
C. A positive test result indicates the presence of orthostatic albuminuria
D. Testing should be part of the routine urinalysis

A

A. Testing may detect early renal involvement in diabetes mellitus

35
Q
  1. Dry reagent strip tests for microalbuminuria that compare albumin to creatinine determine the creatinine concentration based on which principle?

A. Formation of a Cu+2–creatinine complex
B. Enzymatic assay using sarcosine oxidase and peroxidase
C. Reaction of creatinine with alkaline sodium picrate
D. Change in pH as creatinine is converted to creatine

A

A. Formation of a Cu+2–creatinine complex

36
Q
  1. Which of the following conditions is least likely to be detected by dry reagent strip tests for proteinuria?

A. Orthostatic albuminuria
B. Chronic renal failure
C. Pyelonephritis
D. Renal tubular proteinuria

A

D. Renal tubular proteinuria

37
Q
  1. The normal renal threshold for glucose is:

A. 70 to 85 mg/dL
B. 100 to 115 mg/dL
C. 130 to 145 mg/dL
D. 165 to 180 mg/dL

A

D. 165 to 180 mg/dL

38
Q
  1. In which of the following conditions is glycosuria most likely?

A. Addison disease
B. Hypothyroidism
C. Pregnancy
D. Hypopituitarism

A

C. Pregnancy

39
Q
  1. In addition to ascorbate, the glucose oxidase reaction may be inhibited by which substance?

A. Acetoacetic acid (AAA)
B. ε-Aminocaproic acid
C. Creatinine
D. Azopyridium

A

A. Acetoacetic acid (AAA)

40
Q
  1. A positive glucose oxidase test and a negative test for reducing sugars indicates:

A. True glycosuria
B. False-positive reagent strip test result
C. False-negative reducing test result caused by ascorbate
D. Galactosuria

A

A. True glycosuria

41
Q
  1. A negative glucose oxidase test and a positive test for reducing sugars in urine indicates:

A. True glycosuria
B. A false-negative glucose oxidase reaction
C. The presence of a nonglucose reducing sugar, such as galactose
D. A trace quantity of glucose

A

C. The presence of a nonglucose reducing sugar, such as galactose

42
Q
  1. In what condition may urinary ketone tests underestimate ketosis?

A. Acidosis
B. Hemolytic anemia
C. Renal failure
D. Excessive use of vitamin C

A

A. Acidosis

43
Q
  1. AAA is detected in urine by reaction with:

A. Sodium nitroprusside
B. o-Toluidine
C. m-Dinitrobenzene
D. m-Dinitrophenylhydrazine

A

A. Sodium nitroprusside

44
Q
  1. Nondiabetic ketonuria can occur in all of the following except:

A. Pregnancy
B. Renal failure
C. Starvation
D. Lactate acidosis

A

B. Renal failure

45
Q
  1. Which of the following statements regarding the classic nitroprusside reaction for ketones is true?

A. The reaction is most sensitive to acetone
B. Nitroprusside reacts with acetone, AAA, and β-hydroxybutyric acid
C. It may be falsely positive in phenylketonuria
D. The reaction is recommended for diagnosing ketoacidosis

A

C. It may be falsely positive in phenylketonuria

46
Q
  1. Hemoglobin in urine can be differentiated from myoglobin by using:

A. 80% ammonium sulfate to precipitate hemoglobin
B. Sodium dithionite to reduce hemoglobin
C. o-Dianisidine instead of benzidine as the color indicator
D. The dry reagent strip blood test

A

A. 80% ammonium sulfate to precipitate hemoglobin

47
Q
  1. Which of the following conditions is associated with a negative blood test result and an increase in urine urobilinogen?

A. Calculi of the kidney or bladder
B. Malignancy of the kidney or urinary system
C. Crush injury
D. Extravascular hemolytic anemia

A

D. Extravascular hemolytic anemia

48
Q
  1. Which statement about the dry reagent strip blood test is true?

A. The test is based on the reaction of hemoglobin with peroxidase
B. Abnormal color may be absent from the urine when the reaction is positive
C. A nonhemolyzed trace is present when there are 1 to 2 RBCs per high-power field (RBCs/HPF)
D. Salicylates cause a false-positive reaction

A

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

49
Q
  1. 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?

A. Transfusion reaction
B. Myoglobinuria
C. Intravascular hemolytic anemia
D. Recent urinary tract catheterization

A

D. Recent urinary tract catheterization

50
Q
  1. Which of the following results are discrepant?

A. Small amount of blood, but negative protein
B. Moderate amount of blood, but no RBCs in microscopic examination
C. Negative blood, but 6 to 10 RBCs/HPF
D. Negative blood, but positive protein

A

C. Negative blood, but 6 to 10 RBCs/HPF

51
Q
  1. Which of the following statements regarding the dry reagent strip test for bilirubin is true?

A. A positive test result is seen in prehepatic, hepatic, and posthepatic jaundice
B. The test detects only conjugated bilirubin
C. Standing urine may become falsely positive because of bacterial contamination
D. High levels of ascorbate will cause positive interference

A

B. The test detects only conjugated bilirubin

52
Q
  1. Which of the following reagents is used to detect urobilinogen in urine?

A. p-Dinitrobenzene
B. p-Aminosalicylate
C. p-Dimethylaminobenzaldehyde
D. p-Dichloroaniline

A

C. p-Dimethylaminobenzaldehyde

53
Q
  1. Which of the following statements regarding urinary urobilinogen is true?

A. Diurnal variation occurs, and the highest levels are seen in the early morning
B. High levels accompanied by a positive bilirubin test result indicate obstructive jaundice
C. Dry reagent strip tests do not detect decreased levels
D. False-positive results may occur if urine is stored for more than 2 hours

A

C. Dry reagent strip tests do not detect decreased levels

54
Q
  1. Which of the following statements regarding the test for nitrite in urine is true?

A. It detects more than 95% of clinically significant bacteriuria
B. Formation of nitrite is unaffected by the urine pH
C. The test is dependent on adequate dietary nitrate content
D. A positive test differentiates bacteriuria from in vitro bacterial contamination

A

C. The test is dependent on adequate dietary nitrate content

55
Q
  1. Which statement about the dry reagent strip test for leukocytes is true?

A. The test detects only intact white blood cells (WBCs)
B. The reaction is based on the hydrolysis of substrate by WBC esterases
C. Several antibiotics may give a false-positive reaction
D. The test is sensitive to 2 to 3 WBCs/HPF

A

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

56
Q
  1. Which of the following statements about creatinine clearance is correct?

A. Dietary restrictions are required during the 24 hours preceding the test
B. Fluid intake must be restricted to below 600 mL in the 6 hours preceding the test
C. Creatinine clearance is mainly determined by renal tubular function
D. Creatinine clearance is dependent on lean body mass

A

D. Creatinine clearance is dependent on lean body mass

57
Q
  1. A male patient’s eGFR is 75 mL/min. This indicates:

A. Normal glomerular filtration rate
B. The patient is uremic and will be hyperkalemic
C. Renal tubular dysfunction
D. Reduced glomerular filtration without uremia

A

D. Reduced glomerular filtration without uremia

58
Q
  1. Which of the following substances can be used to calculate eGFR?

A. p-Aminohippuric acid (PAH)
B. Glycine
C. Cysteine
D. Cystatin C

A

D. Cystatin C

59
Q
  1. Which statement regarding urea is true?

A. Urea is 100% filtered by the glomeruli
B. Blood urea levels are independent of diet
C. Urea is not significantly reabsorbed by the tubules
D. Urea excretion is a specific measure of glomerular function

A

A. Urea is 100% filtered by the glomeruli

60
Q
  1. 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

A. 47 mL/min
B. 78 mL/min
C. 100 mL/min
D. 116 mL/min

A

B. 78 mL/min

The clearance formula is
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):

100 mg/dL ÷ 1.2 mg/dL × 1.4L/day × 1,000 mL/L × 1 day/1,440 min × (1.73 m2 ÷ 1.8 m2) = 78 mL/min

Note that the creatinine clearance is low (lower reference limit approximately 95 mL/min for males and 85 mL/min for females), although the serum creatinine is still within normal limits (0.5–1.2 mg/dL). The clearance test is more sensitive if done properly because as serum creatinine goes up, urine creatinine goes down.

BOC review-Harr 5th ed (59 decks)

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