7.1 Routine Physical and Biochemical Urine Tests Flashcards
Which statement regarding renal function is true?
Glomeruli are far more permeable to H2O and salt compared with other capillaries
Which statement regarding normal salt and H2O handling by the nephron is correct?
The thick ascending limb of the tubule is highly permeable to salt but not H2O
Which statement concerning renal tubular function is true?
In salt deprivation, the kidneys will conserve sodium at the expense of potassium
Which of the following is inappropriate when collecting urine for routine bacteriologic culture?
The sample may be held at 2°C to 8°C for up to 48 hours prior to plating
Which statement about sample collection for routine urinalysis is true?
Samples may be stored at room temperature for up to 2 hours
Which urine color is correlated correctly with the pigment-producing substance?
Deep yellow urine and yellow foam with bilirubin
Which of the following substances will cause urine to produce red fluorescence when examined under an ultraviolet lamp (360 nm)?
Coproporphyrin
Which of the following conditions is associated with normal urine color but produces red fluorescence when urine is examined with an ultraviolet (Wood) lamp?
Lead poisoning
Which statement regarding porphyria is accurate?
Serum, urine, and fecal tests may be needed for diagnosis
Which is the most common form of porphyria?
Porphyria cutanea tarda
Which of the following methods is the least sensitive and specific for measuring PBG in urine?
Watson-Schwartz test
A brown or black pigment in urine can be caused by:
Melanin
Urine that is dark red or port wine-colored may be caused by:
Porphyria cutanea tarda
Which of the following tests is affected least by standing or improperly stored urine?
Protein
Which one of the following characteristics would be a reason for performing a microscopic examination of urinary sediment?
Turbidity
Which of the following is appropriate when collecting a 24-hour urine sample for metanephrines?
All urine should be collected in a single container that is kept refrigerated
Urine production of less than 400 mL/day is:
Defined as oliguria
Which of the following contributes to SG, but not to osmolality?
Protein
Urine with an SG consistently between 1.002 and 1.003 indicates:
Diabetes insipidus
In which of the following conditions is the urine SG likely to be below 1.025?
Chronic renal failure
Which statement regarding methods for measuring SG is true?
Colorimetric SG readings are falsely low when pH is alkaline
What is the principle of the colorimetric reagent strip determination of SG in urine?
Ionic strength alters the pKa of a polyelectrolyte
Which statement regarding urine pH is true?
Contamination should be suspected if urine pH is less than 4.5
In renal tubular acidosis, the pH of urine is:
Consistently alkaline
The normal daily urine output for an adult is approximately:
0.6 to 1.6 L
The SG of the filtrate in the Bowman space is approximately:
1.008 to 1.010
A patient with partially compensated respiratory alkalosis would have a urine pH of:
7.5 to 8.5
Which of the following is most likely to cause a false-positive result on the dry reagent strip test for urinary protein?
Highly buffered alkaline urine
When testing for urinary protein with sulfosalicylic acid (SSA), which condition may produce a false-positive result?
The presence of x-ray contrast media
A discrepancy between the urine SG determined by measuring refractive index and urine osmolality would be most likely to occur:
After intravenous pyelography (IVP)
Which of the following is likely to result in a false-negative dry reagent strip test for proteinuria?
Bence-Jones protein
Daily loss of protein in urine normally does not exceed:
150 mg
Which of the following is least likely to cause a false-positive result on turbidimetric protein tests?
Ascorbic acid
Which statement best describes the clinical utility of tests for microalbuminuria?
Testing may detect early renal involvement in diabetes mellitus
Dry reagent strip tests for microalbuminuria that compare albumin to creatinine determine the creatinine concentration based on which principle?
Formation of a Cu+2–creatinine complex
Which of the following conditions is least likely to be detected by dry reagent strip tests for proteinuria?
Renal tubular proteinuria
The normal renal threshold for glucose is:
165 to 180 mg/dL
In which of the following conditions is glycosuria most likely?
Pregnancy
In addition to ascorbate, the glucose oxidase reaction may be inhibited by which substance?
Acetoacetic acid (AAA)
A positive glucose oxidase test and a negative test for reducing sugars indicates:
True glycosuria
A negative glucose oxidase test and a positive test for reducing sugars in urine indicates:
The presence of a nonglucose reducing sugar, such as galactose
In what condition may urinary ketone tests underestimate ketosis?
Acidosis
AAA is detected in urine by reaction with:
Sodium nitroprusside
Nondiabetic ketonuria can occur in all of the following except:
A. Pregnancy
B. Renal failure
C. Starvation
D. Lactate acidosis
Renal failure
Which of the following statements regarding the classic nitroprusside reaction for ketones is true?
It may be falsely positive in phenylketonuria
Hemoglobin in urine can be differentiated from myoglobin by using:
80% ammonium sulfate to precipitate hemoglobin
Which of the following conditions is associated with a negative blood test result and an increase in urine urobilinogen?
Extravascular hemolytic anemia
Which statement about the dry reagent strip blood test is true?
Abnormal color may be absent from the urine when the reaction is positive
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?
Recent urinary tract catheterization
Which of the following results are discrepant?
Negative blood, but 6 to 10 RBCs/HPF
Which of the following statements regarding the dry reagent strip test for bilirubin is true?
The test detects only conjugated bilirubin
Which of the following reagents is used to detect urobilinogen in urine?
p-Dimethylaminobenzaldehyde
Which of the following statements regarding urinary urobilinogen is true?
Dry reagent strip tests do not detect decreased levels
Which of the following statements regarding the test for nitrite in urine is true?
The test is dependent on adequate dietary nitrate content
Which statement about the dry reagent strip test for leukocytes is true?
The reaction is based on the hydrolysis of substrate by WBC esterases
Which of the following statements about creatinine clearance is correct?
Creatinine clearance is dependent on lean body mass
A male patient’s eGFR is 75 mL/min. This indicates:
Reduced glomerular filtration without uremia
Which of the following substances can be used to calculate eGFR?
Cystatin C
Which statement regarding urea is true?
Urea is 100% filtered by the glomeruli
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
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)
