4.7 BILIRUBIN AND UROBILINOGEN

Question 1

Identify the form of bilirubin that appears in the urine when liver disease disrupts the normal bilirubin degradation cycle.

Answer 1

Conjugated bilirubin

Question 2

Identify the key factor that causes bilirubin to appear in the urine.

Answer 2

Disruption of the normal bilirubin degradation cycle due to bile duct obstruction or liver damage.

Question 3

Identify the types of jaundice associated with bilirubinuria.

Answer 3

Posthepatic jaundice (bile duct obstruction) and hepatic jaundice (liver damage).

Question 4

Identify the test method commonly used to detect bilirubin in urine

Answer 4

The diazo reaction with reagent strips.

Question 5

Identify the chemical used in the diazo reaction for detecting bilirubin in urine.

Answer 5

2,4-dichloroaniline diazonium salt or 2,6-dichlorobenzene-diazonium-tetrafluoroborate.

Question 6

Identify the common interferences that can cause a false-positive result in bilirubin testing

Answer 6

Urine pigments (e.g., phenazopyridine compounds), indican, and metabolites of Lodine

Question 7

Identify the factor that commonly causes a false-negative result in bilirubin testing

Answer 7

Exposure of the specimen to light, which causes bilirubin to photo-oxidize into biliverdin

Question 8

Identify the confirmatory test for bilirubin in urine.

Answer 8

The Ictotest

Question 9

Identify the sensitivity of the Ictotest for bilirubin detection.

Answer 9

0.05 to 0.1 mg/dL of bilirubin.

Question 10

Identify the key byproducts of bilirubin metabolism in the intestine

Answer 10

Urobilinogen and stercobilinogen

Question 11

Identify the normal concentration range for urobilinogen in urine.

Answer 11

Less than 1 mg/dL (1 Ehrlich unit).

Question 12

Identify the clinical conditions that cause an increase in urinary urobilinogen.

Answer 12

Liver disease and hemolytic disorders

Question 13

Identify the reagent used in Multistix to detect urobilinogen

Answer 13

p-dimethylaminobenzaldehyde (Ehrlich reagent).

Question 14

Identify the reagent used in Chemstrip to detect urobilinogen.

Answer 14

4-methoxybenzene-diazonium-tetrafluoroborate

Question 15

Identify the potential interference that could cause false-positive results in the Multistix urobilinogen test.

Answer 15

Ehrlich-reactive compounds such as porphobilinogen, indican, and certain medications (e.g., sulfonamides, methyldopa)

Question 16

Identify the condition in which the absence of urobilinogen in urine and feces is diagnostically significant.

Answer 16

Biliary obstruction.

Question 17

Identify the main pigment responsible for the brown color of feces

Answer 17

Stercobilin

Question 18

Identify the compound that is produced when urobilinogen is oxidized in the intestine.

Answer 18

Urobilin

Question 19

Identify the liver condition that results in the leakage of conjugated bilirubin into the bloodstream, causing bilirubinuria.

Answer 19

Hepatitis or cirrhosis

Question 20

Identify the condition that can cause the absence of bilirubin in the urine despite the presence of jaundice.

Answer 20

Hemolytic disease, where unconjugated bilirubin is present in the serum but not excreted in the urine.

Question 21

Identify the type of jaundice caused by gallstones or cancer obstructing the bile duct

Answer 21

Posthepatic (biliary) jaundice

Question 22

Identify the substance formed when bilirubin undergoes conjugation in the liver.

Answer 22

Bilirubin diglucuronide (conjugated bilirubin

Question 23

Identify the main reason bilirubin is not normally found in the urine under healthy conditions

Answer 23

Conjugated bilirubin is excreted into the bile and passed into the intestine, not the urine

Question 24

Identify the organ responsible for converting bilirubin into urobilinogen in the intestine

Answer 24

Intestinal bacteria.

Question 25

Identify the substance that results from the oxidation of urobilinogen in the feces

Answer 25

Stercobilin

Question 26

Identify the substance formed when urobilinogen is oxidized in the urine

Answer 26

Urobilin

Question 27

Identify the testing procedure that uses p-nitrobenzenediazonium-p-toluenesulfonate for bilirubin detection.

Answer 27

Ictotest procedure

Question 28

Identify the color change that indicates a positive result for bilirubin in the Ictotest

Answer 28

A blue-to-purple color

Question 29

Identify the clinical significance of increased urinary urobilinogen in a patient with liver disease

Answer 29

Impaired liver function leads to decreased processing of recirculated urobilinogen, causing excess urobilinogen to be filtered by the kidneys and appear in the urine.

Question 30

Identify the clinical significance of absent urobilinogen in the urine and pale stools.

Answer 30

Biliary obstruction preventing the normal passage of bilirubin into the intestine.

Question 31

Identify the substance that causes a false-negative result in urobilinogen testing when specimens are improperly preserved

Answer 31

Photo-oxidation of urobilinogen to urobilin

Question 32

Identify the test used for detecting urobilinogen in urine that produces a pink color with a positive result.

Answer 32

The Multistix test using the Ehrlich reaction

Question 33

Identify the reagent used in the Ehrlich reaction for urobilinogen detection on Multistix.

Answer 33

p-dimethylaminobenzaldehyde (Ehrlich reagent).

Question 34

Identify the type of chemical reaction used by Chemstrip to detect urobilinogen in urine

Answer 34

Azo-coupling (diazo) reaction

Question 35

Identify the condition where urobilinogen can be elevated due to hemolysis

Answer 35

Hemolytic disorders, where increased unconjugated bilirubin leads to more urobilinogen production