Urine Physical Examination Quiz

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Questions and Answers

What is the primary pigment that gives urine its yellow color?

Uroerythrin

Urates

Urochrome (correct)

Urobilin

Orange-brown color in urine can be caused by fresh urine.

False

What is a common cause of colorless urine?

Recent fluid consumption

A dark yellow urine can be caused by __________.

dehydration Signup and view all the answers

Match the urine clarity conditions with their potential causes:

Colorless urine = Recent fluid consumption Pale yellow urine = Diabetes mellitus Dark yellow urine = Dehydration Orange-yellow urine = Phenazopyridine Signup and view all the answers

What is the specific gravity of urine that is considered isosthenuric?

1.010 Signup and view all the answers

The refractive index does not compare light velocity in air with light velocity in solutions.

False Signup and view all the answers

A specific gravity lower than 1.002 likely indicates what?

Diluted urine Signup and view all the answers

What happens to the pH of urine when the concentration increases?

It decreases as more hydrogen ions are released. Signup and view all the answers

What is the time frame for the leukocyte esterase reaction?

2 minutes Signup and view all the answers

Which of the following indicators is part of the double indicator system used for pH testing in urine?

Methyl red Signup and view all the answers

Which substance can cause a false positive result in the leukocyte esterase test?

Formalin Signup and view all the answers

What may high levels of nitrite in urine indicate?

Bacterial contamination Signup and view all the answers

What is a potential false negative cause for leukocyte esterase testing?

Formalin Signup and view all the answers

What occurs during the first step of the double sequential enzyme reaction involving glucose oxidase?

Glucose is oxidized to gluconic acid and hydrogen peroxide Signup and view all the answers

Which substance is used as a chromogen in the glucose oxidase reaction?

Tetramethylbenzidine Signup and view all the answers

What can lead to a false negative result in glucose testing?

High alkaline urine with a pH greater than 6.5 Signup and view all the answers

If a urine test shows a positive result for glucose but a false negative interpretation occurs, what could be the source of interference?

Ascorbic acid Signup and view all the answers

Which of the following indicates that the specific gravity of urine is high?

Color change from blue to shades of green Signup and view all the answers

What type of substances can result in a positive glucose test aside from glucose itself?

Various non-glucose reducing substances Signup and view all the answers

Which of the following factors could cause a false positive in glucose testing?

High concentration of protein in urine Signup and view all the answers

What is the color range change of the indicator pad due to specific gravity increase?

From blue to shades of green to yellow Signup and view all the answers

Which substance can indicate the presence of hematuria when a positive reagent strip is observed?

Nitrite Signup and view all the answers

What is the principle behind the detection of certain components in urine using a chromogen?

Change in pKa of polyelectrolytes Signup and view all the answers

What effect does exposure to light have on certain urine specimens?

Causes pigmented appearance Signup and view all the answers

What can cause a false positive result when testing for hemoglobin in urine?

Oxidizing agent use Signup and view all the answers

Which condition can result in bilirubinuria?

Cirrhosis of the liver Signup and view all the answers

What pH change can affect the measurement of polyelectrolyte ionization in urine testing?

Alkaline medium Signup and view all the answers

What is indicated by a chromogenic reaction that changes from green to blue during urine testing?

Presence of hemoglobin Signup and view all the answers

What level of ascorbic acid in urine can cause a false negative result in testing?

Greater than 25 mg/dL Signup and view all the answers

What pH range indicates a normal random sample of urine?

4.5-8.0 Signup and view all the answers

What may cause a false acidic reading in alkaline urine?

Dilute alkaline run Signup and view all the answers

Which factor can alter the color of the protein indicator without changing the pH?

Presence of histiocytes Signup and view all the answers

What indicates an improperly preserved urine sample?

pH of 8.5 or higher Signup and view all the answers

Which of the following is a key component of the protein error of indicator principle?

Color alteration without changing pH Signup and view all the answers

What can contribute to elevated protein levels greater than 500 mg/dL in urine?

Infection or inflammation Signup and view all the answers

What is a characteristic of bilirubin as a compound?

It is a product of hemoglobin degradation. Signup and view all the answers

What limitation is associated with the measurement of bilirubin?

It only measures direct bilirubin. Signup and view all the answers

Which time frame is associated with the principle of bilirubin measurement using the diazo reaction?

30 seconds Signup and view all the answers

What is the primary principle behind the reaction that detects acetoacetate?

Sodium nitroprusside reaction. Signup and view all the answers

Which of the following is a potential false positive for bilirubin tests?

Levadopa Signup and view all the answers

Which intermediate product of fat metabolism is mentioned?

Acetone Signup and view all the answers

What can lead to false negative results when testing for bilirubin?

Improper preservation of the specimen. Signup and view all the answers

What is the color indication for a rise in bilirubin levels in urine?

Increasing degrees of tan to pink Signup and view all the answers

Study Notes

Urine Examination Overview

Physical examination of urine includes assessment of color, clarity, specific gravity, and odor.

Color

Urochrome is the yellow pigment responsible for urine color, stemming from endogenous metabolism.
Additional pigments include:
- Uroerythrin: contributes pink color in sediments.
- Urobilin: an oxidation product imparting an orange-brown color to non-fresh urine.

Urine Color Interpretation

Colorless urine may indicate recent fluid consumption.
Pale yellow urine can suggest:
- Polyuria or diabetes insipidus.
- Diabetes mellitus.
Dark yellow urine is associated with:
- Dehydration.
- Vitamin B complex consumption.
- Presence of bilirubin or certain medications (e.g., acriflavine, nitrofurantoin).
Orange-yellow urine can result from medications like phenazopyridine.
Yellow-green urine indicates bilirubin oxidation to biliverdin.
Green urine is often linked to Pseudomonas infection.
Blue-green urine can result from drugs such as amitriptyline or methocarbamol.

Urine Clarity

Clarity refers to transparency and turbidity. Assessed by observing the specimen against a light source.
Causes of turbidity can be subdivided:
- Pathological:
  - Presence of RBCs, WBCs, abnormal crystals, bacteria, or lymph fluid.
- Nonpathological:
  - Squamous epithelial cells, mucus, amorphous phosphates, semen, and radiographic contrast dye.

Procedure for Assessing Color and Clarity

Use a well-mixed specimen and evaluate through a clear container against a white background with adequate lighting.
Maintain consistent volume for accurate assessment.

Specific Gravity

Defined as the density of urine compared to distilled water (SG 1.000).
Typical specific gravity ranges from 1.015 to 1.030.
Isosthenuric is at 1.010, while hyposthenuric is below this, and hypersthenuric is above.

Measurement Techniques

Refractometer measures urine concentration by assessing the refractive index.
Corrections are needed for protein (subtract 0.003) and glucose (subtract 0.004) concentrations in the urine sample.
Osmolality measures colligative properties by particle count.
Reagent strips assess pKa changes related to ion presence, not larger molecules.

Odor

Fresh urine typically has a faint, aromatic odor.
Odor variations can indicate different conditions or substances:
- Sweet odor may indicate diabetes.
- Strong ammonia smell can suggest dehydration or infection.

Glucose Testing

The process involves a double sequential enzyme reaction.
Reactants include glucose and oxygen, with glucose oxidase producing gluconic acid and hydrogen peroxide.
The second reaction uses hydrogen peroxide and a chromogen with peroxidase to yield an oxidized colored chromogen and water.
Glucose concentrations are identified as either positive or negative, with the presence of reducing substances impacting results.

Copper Reduction Interpretation

Chromogen indicators include potassium iodide (transitions from green to brown) and tetramethylbenzidine (yellow to green).
Negative results may indicate the presence of non-glucose reducing substances or interference from ascorbic acid.
Reporting includes negative, trace, and graded positives (1+ to 4+).
Time frame for reactions is 30 seconds.

Specific Gravity (SG) Testing

Specific gravity readings reflect urine concentration, shifting from blue in alkaline to green/yellow in acidic conditions.
False negatives can arise from ascorbic acid, high specific gravity, or pathological conditions.
False positives may be due to high protein concentration or oxidizing agents present.

Ketone Testing

Ketones, an intermediate metabolic product, include acetone and acetoacetic acid, detected by respective test strips.
Testing involves sodium nitroprusside reacting with acetone in alkaline conditions, resulting in a purple color change.
Time frame for this reaction is 40 seconds.

Bilirubin Testing

Bilirubin is a degradation product of hemoglobin, measured using a diazo reaction.
False positives can occur with pigmented specimens or specific medications, such as levodopa.
Confirmatory tests (Ictotest) detect bilirubin in urine.
Only conjugated bilirubin (direct) will appear in urine.

Blood Testing

The presence of blood is indicated through pseudo peroxidase activity of hemoglobin.
Reaction time is 60 seconds, detecting conditions such as hematuria and hemoglobinuria using a chromogen reaction.
False positives may arise due to nitrite concentration or specimen contamination.

pH Testing

The pH is determined using a double indicator system (methyl red and bromthymol blue).
Normal urine pH ranges from 4.5 to 8.0; pH above 8.5 suggests specimen preservation issues.
False acidic readings can occur in alkaline urine scenarios.

Protein Testing

The principle involves a protein error of the indicator, which can alter color without pH change.
Significant protein levels can cause false positives, especially in highly pigmented urine.
Proper timing and method of urine specimen preservation are crucial for accurate results.

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Description

This quiz focuses on the physical examination of urine, specifically on aspects like color and clarity. Test your knowledge on urochrome and the historical methods used for urine analysis. Perfect for students in healthcare or biology fields.