Interferences - Based on Tutorial

Question 1

Which three specimen integrity issues are most common in clinical chemistry?
A) Hemolysis, icterus, lipemia
B) Proteinuria, glycosuria, hematuria
C) Hypercalcemia, hypokalemia, hypernatremia
D) Leukocytosis, thrombocytopenia, anemia

Answer 1

A) Hemolysis, icterus, lipemia

Question 2

What is the main cause of in vitro hemolysis?
A) Hemolytic anemia
B) Phlebotomy technique errors
C) Sepsis
D) Parasite infection

Answer 2

B) Phlebotomy technique errors

Question 3

Which of the following is NOT a cause of in vitro hemolysis?
A) Narrow gauge needles
B) Forceful use of syringe
C) Tight tourniquet
D) Genetic hemoglobinopathy

Answer 3

D) Genetic hemoglobinopathy

Question 4

What is a common cause of in vivo hemolysis?
A) Overly vigorous shaking of blood tube
B) Hemolytic anemia
C) Suboptimal centrifugation
D) Improper specimen transport

Answer 4

B) Hemolytic anemia

Question 5

What percentage of hemolyzed samples are due to in vivo hemolysis?
A) Less than 2%
B) 10%
C) 25%
D) 50%

Answer 5

A) Less than 2%

Question 6

What is considered malpractice in the context of in vivo hemolysis?
A) Accepting hemolyzed samples
B) Rejection of suspected in vivo hemolysis samples
C) Using narrow gauge needles
D) Not using a tourniquet

Answer 6

B) Rejection of suspected in vivo hemolysis samples

Question 7

Which laboratory finding is a reliable marker for in vivo hemolysis?
A) Elevated plasma potassium
B) Reduced plasma haptoglobin
C) Increased serum albumin
D) Decreased bilirubin

Answer 7

B) Reduced plasma haptoglobin

Question 8

What is a typical sign of in vivo hemolysis?
A) Decreased reticulocyte count
B) Elevation of indirect bilirubin
C) Decreased LDH
D) Increased serum sodium

Answer 8

B) Elevation of indirect bilirubin

Question 9

Which mechanism of hemolysis interference increases absorbance in the hemoglobin spectral range?
A) Release of proteases
B) Release of hemoglobin
C) Water release
D) Inhibition of reactions

Answer 9

B) Release of hemoglobin

Question 10

Which mechanism of hemolysis interference can result in falsely lower concentrations of proteins?
A) Release of hemoglobin
B) Release of proteases
C) Water release
D) Increased absorbance

Answer 10

B) Release of proteases

Question 11

Which analyte is falsely increased in hemolyzed samples due to release from red blood cells?
A) Sodium
B) Potassium
C) Calcium
D) Chloride

Answer 11

B) Potassium

Question 12

What is a common effect of water release from red blood cells during hemolysis?
A) Dilution of serum constituents
B) Increased absorbance
C) Inhibition of chemical reactions
D) Release of proteases

Answer 12

A) Dilution of serum constituents

Question 13

What is the most common cause of lipemia in blood tubes?
A) Hemolysis
B) Patient not fasting before blood draw
C) Elevated bilirubin
D) High glucose levels

Answer 13

B) Patient not fasting before blood draw

Question 14

Lipemia makes plasma or serum appear:
A) Pinkish-red
B) Milky white and turbid
C) Yellow-green
D) Clear and colorless

Answer 14

B) Milky white and turbid

Question 15

Severe lipemia can occur with which condition?
A) Diabetes mellitus
B) Genetic hyperlipidemias
C) Recent intravenous lipid infusion
D) All of the above

Answer 15

D) All of the above

Question 16

Which lipoproteins cause the most turbidity in lipemic samples?
A) Chylomicrons and large VLDL
B) Small VLDL and LDL
C) HDL only
D) LDL and HDL

Answer 16

A) Chylomicrons and large VLDL

Question 17

Lipemia can interfere with laboratory analysis by:
A) Absorbance and scattering of light
B) Volume displacement
C) Physico-chemical effects
D) All of the above

Answer 17

D) All of the above

Question 18

Which analyte measurement is most affected by volume displacement in lipemic samples?
A) Electrolytes
B) Glucose
C) Bilirubin
D) Albumin

Answer 18

A) Electrolytes

Question 19

What is the simplest recommendation to avoid lipemia?
A) Use lipid-clearing reagents
B) Encourage fasting collection
C) Ultracentrifugation
D) Dilute the sample

Answer 19

B) Encourage fasting collection

Question 20

What is a laboratory maneuver to reduce lipemia in a specimen?
A) Addition of lipid-clearing reagents
B) Ultracentrifugation and manual removal of lipid layer
C) Dilution methods
D) All of the above

Answer 20

D) All of the above

Question 21

What is a limitation of visual inspection for hemolysis and lipemia?
A) It is highly subjective
B) It is very expensive
C) It requires special equipment
D) It is very slow

Answer 21

A) It is highly subjective

Question 22

What are serum indices?
A) Spectrophotometric estimates of specimen interference from icterus, lipemia, or hemolysis
B) Visual inspection scores
C) Manual calculations
D) Blood pressure readings

Answer 22

A) Spectrophotometric estimates of specimen interference from icterus, lipemia, or hemolysis

Question 23

Which wavelengths are used to measure lipemia in Cobas C systems?
A) 700/660 nm
B) 600/570 nm
C) 505/480 nm
D) 400/420 nm

Answer 23

A) 700/660 nm

Question 24

Which wavelengths are used to measure hemolysis in Cobas C systems?
A) 700/660 nm
B) 600/570 nm
C) 505/480 nm
D) 400/420 nm

Answer 24

B) 600/570 nm

Question 25

Which wavelengths are used to measure icterus in Cobas C systems? A) 700/660 nm B) 600/570 nm C) 505/480 nm D) 400/420 nm

Answer 25

C) 505/480 nm

Question 26

What is the visual appearance of a hemolyzed plasma sample? A) Clear and colorless B) Milky white C) Pinkish red D) Yellow-green

Answer 26

C) Pinkish red

Question 27

What is the visual appearance of a lipemic plasma sample? A) Clear and colorless B) Milky white or cloudy yellow C) Pinkish red D) Yellow-green

Answer 27

B) Milky white or cloudy yellow

Question 28

What is the visual appearance of an icteric plasma sample? A) Clear and colorless B) Milky white C) Pinkish red D) Yellow-green

Answer 28

D) Yellow-green

Question 29

What is the main effect of hemolysis on potassium measurement? A) Falsely low potassium B) Falsely high potassium C) No effect D) Variable effect

Answer 29

B) Falsely high potassium

Question 30

Why is it important to monitor HIL interference in clinical laboratories? A) To reduce reagent costs B) To avoid misdiagnosis and inappropriate treatment C) To increase sample volume D) To speed up testing

Answer 30

B) To avoid misdiagnosis and inappropriate treatment