| Which of the following tests included on a urine reagent strip would never be reported out as negative? | View Page |
| Excessive carbohydrate loss that may occur due to vomiting, or rapid weight loss may result in the presence of which of following substances not normally contained in the urine? | View Page |
| Which of the following reagent strip tests is based on the Ehrlich- aldehyde reaction. | View Page |
| Sulfosalicylic acid can be used to confirm the result of which of the following tests included on a urine reagent strip? | View Page |
| Bilirubin Characterization Bilirubin, a product of hemoglobin breakdown, is characterized by its yellow pigment. The presence of bilirubin in urine is always abnormal. It is important to note that unconjugated bilirubin cannot be excreted by the kidneys because it is bound to albumin and is not soluble in water. In the liver, bilirubin combines with glucuronic acid through the action of a glucuronyl transferase to form water soluble bilirubin diglucuronide. Under normal circumstances, conjugated bilirubin passes from the bile duct and then to the intestinal tract. Intestinal bacteria reduce conjugated bilirubin to urobilinogen. Approximately half of the urobilinogen is excreted in the feces; most of the other half is recirculated through the liver. A small amount of urobilinogen bypasses the liver and is excreted in the urine. | View Page |
| Which of the following may cause a false positive bilirubin result on a urine reagent strip? | View Page |
| Which of the following may cause false negative bilirubin results on a urine reagent strip? (Choose ALL of the correct answers) | View Page |
| Urobilinogen Urobilinogen is a byproduct of hemoglobin breakdown. It is produced in the intestinal tract as a result of the action of bacteria on bilirubin. Almost half of the urobilinogen produced recirculates through the liver and then returns to the intestines through the bile duct. Urobilinogen is then excreted in the feces where it is converted to urobilin. As the urobilinogen circulates in the blood to the liver, a portion of it is diverted to the kidneys and appears as urinary urobilinogen. Up to 1 mg/dL or Ehrlich unit of urobilinogen is present in normal urine. A result of 2.0 mg/dL represents the transition from normal to abnormal and the patient should be evaluated further. It is important to note that the reagent strip cannot determine the absence of urobilinogen. | View Page |
| The Test for Urobilinogen The test for urobilnogen is based on the Ehrlich Aldehyde Reaction. P-dimethylaminobenzaldehyde in an acid medium with a color enhancer reacts with urobilinogen to form a pink-red color. The strip reactivity increases with increasing temperature. The optimum temperature for testing is 22° - 26°C. A freshly voided sample is best for optimal results. | View Page |
| False Positive Urobilinogen Results A false positive urobilinogen reaction may occur with the dipstick method when substances known to react with Ehrlich's reagent such as sulfonamides and p-aminosalicylic acid are present in the urine. Drugs that contain Azo dyes, such as Azo Gantrisin®, have a gold color that masks the reaction, causing a false positive reaction. Atypical color reactions may be obtained in the presence of high concentrations of p-aminobenzoic acid. The dipstick urobilinogen test cannot detect porphobilinogen in a urine specimen. Porphobilinogen is a molecule formed during the synthesis of the heme portion of hemoglobin. | View Page |
| False Negative Urobilinogen Result Due to the instability of urobilinogen, a false negative result may occur using a dipstick method if the urine specimen has remained at room temperature for an extended period of time in the light. A false negative result may also occur if formalin is present. | View Page |
| Confirmatory Test Test results that are 2.0 Ehrlich units or greater can be confirmed using the Watson-Schwartz qualitative test. This test will differentiate between urobilinogen and porphobilinogen. | View Page |
| Clinical Significance Urinary urobilinogen may be increased in the presence of a hemolytic process such as hemolytic anemia. It may also be increased with infectious hepatitis, or with cirrhosis. Comparing the urinary bilirubin result with the urobilinogen result may assist in distinguishing between red cell hemolysis, hepatic disease, and biliary obstruction. Urobilinogen is increased in hemolytic disease and urine bilirubin is negative. Urobilinogen is increased in hepatic disease, and urine bilirubin may be positive or negative. Urobilinogen is low with biliary obstruction, and urine bilirubin is positive. Reagent strips methods however, cannot distinguish normal urobilinogen from absent urobilinogen, as might be seen in complete biliary obstruction. | View Page |
| Which of the following substances cause a false-positive reaction on the urobilinogen portion of the test strip? (Choose ALL of the correct answers) | View Page |
| Which of the following cause false negative reactions when testing for urobilinogen with the reagent strips? (Choose ALL of the correct answers) | View Page |
| A test that can be used as a confirmatory test for urobilinogen is: | View Page |
| Urobilinogen is excreted in the urine in increased amounts in: (Choose ALL of the correct answers) | View Page |
| To screen for urinary tract infections leukocyte esterase should be coupled with: (Choose ALL of the correct answers) | View Page |