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Questions and Answers
What substance is formed when hydrochloric acid acts on fructose during Seliwanoff’s Test?
What color indicates a positive result for fructose in Seliwanoff’s Test?
What does the presence of sugar in urine typically indicate?
Which of the following substances is NOT classified as a ketone body?
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What happens to excess acetyl CoA in the liver?
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Which cells primarily use ketone bodies as an energy source?
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How are free fatty acids transported to the liver?
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Why can't the liver use ketone bodies as fuels?
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What is the first step in performing Esbach’s test for the total volume of urine?
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When is it necessary to dilute urine before protein testing using Esbach's test?
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What indicates a concentration of protein in the urine greater than 6-8 gm/l?
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What adjustment needs to be made if the urine pH is not acidic during Esbach’s test?
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What does the presence of leukocytes and bacteria in urine suggest?
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What characterizes Bence-Jones protein?
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At what temperature does Bence-Jones protein coagulate during the heat test?
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What should be done after adding Esbach’s reagent to the urine sample?
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What is a characteristic of functional proteinuria?
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Which condition is associated with postural (orthostatic) proteinuria?
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What type of proteinuria is primarily due to kidney disease?
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Which of the following is NOT a cause of pre-renal proteinuria?
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What is one method used to test for urinary protein?
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Which condition does NOT cause systemic disease or renal pathology proteinuria?
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What is accidental or false proteinuria?
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What color indicates a positive result on the Test-Tape after 30 seconds?
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Physiological proteinuria is typically characterized by which of the following?
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How is the reagent area of the Diastix strip utilized?
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What is the function of glucose oxidase in Diastix?
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What is the expected result when glucose is present in Rubner’s Test?
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What is a characteristic of the reagent area in Test-Tape?
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Which of the following conditions might lead to fructose appearing in urine?
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What should be done at 30 seconds when using a Diastix strip?
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What happens to the indicator color on Test-Tape when it oxidizes?
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What does a positive result in Robert's Test indicate?
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What reagent is used in Heller's Test?
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How sensitive is the Sulphosalicylic Acid Test for detecting protein?
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What is the main action that allows the Heat and Acetic Acid Test to work?
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In the procedure of Robert's Test, what indicates a positive outcome?
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What happens during the first step of the Sulphosalicylic Acid Test?
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Why is the lower portion of urine not heated in the Heat and Acetic Acid Test?
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Which of the following tests can detect protein without forming a ring?
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Study Notes
Test-Tape for Glucose
- A screening test for glucose
- Utilizes the same principle as Clinistix
- Employs a different oxidation-reduction indicator and material for reagent impregnation
- Reagents are impregnated on a tear strip of special paper
- Indicator is yellow in its reduced form and green to blue in its oxidized form
Procedure
- Tear off approximately 1 and 1/2 inches of the strip
- Dip the strip into the urine specimen and immediately remove it
- Wait 30 seconds and observe the appearance of green color
- A yellow color indicates negative test
- A green color indicates positive test
Diastix Reagent Strip for Glucose
- A specific test for glucose based on glucose oxidase
- Chemical reaction is the same as Clinistix
- Uses a different chromogen system
- Reagent area contains glucose oxidase, peroxidase, blue background dye, and potassium iodide as the chromogen
Procedure
- Dip the reagent area of the strip into the specimen
- Compare the test area with the color chart after 10 seconds
- Compare the test area with the color chart after 30 seconds for a semi-quantitative result
Rubner’s Test
- Add 3 gms (excess) of lead acetate to 10 ml of undiluted urine
- Shake well and filter
- Boil the filtrate and add 1 ml of concentrated ammonium hydroxide
- Boil the mixture
- A precipitate forms, indicating a positive test
- Lactose: Red solution + Red precipitate
- Glucose: Red solution + Yellow precipitate
Fructose
- Found in urine after consuming fruits, honey, syrup, and jams
- Can be found in liver disease
- Found along with glucose in the urine of diabetics
Seliwanoff’s Test for Fructose
- Hydrochloric acid acts on fructose to form a furfuraldehyde derivative
- Derivative reacts with resorcinol to produce a red-colored compound
- Add a few drops of urine to 5 ml of reagent in a test tube
- Boil the mixture
- A red color within half a minute indicates a positive test
Clinical Significance of Urine Sugar
- Normally, urine does not contain enough sugar for a positive test
- Presence of sugar in urine indicates diabetes mellitus
- Used for screening, confirming diagnosis, and monitoring diabetic therapy
Ketones
- Also known as ketone bodies
- A group of three related substances:
- Acetone
- Acetoacetate (acetoacetic acid)
- β-hydroxybutyrate (β-hydroxybutyric acid)
- Formed in the liver from acetoacetate (oxidation product of amino acid, fatty acid)
- Used as an energy source for extrahepatic tissues like brain and muscle cells
Ketone Bodies as Alternative Fuel
- Normal products of fat metabolism
- Not detectable in the blood or urine of healthy individuals
- Fat is broken down in tissues to glycerol and fatty acids
- Free fatty acids are transported to the liver by plasma albumin and broken down to acetyl coenzyme A (acetyl Co-A)
- Excess acetyl CoA is diverted into ketone bodies
- Ketones are transported to peripheral tissues and oxidized by the TCA cycle
Increased Permeability of the Glomerulus
- Normally, the glomerular membrane is impermeable to protein molecules
- Damage to the glomerular membrane allows protein molecules to pass through
Decrease in Normal Reabsorption
- Disease conditions affect reabsorption in the tubules
Types of Proteinuria
- Classified based on etiology and mechanism
- Functional Proteinuria
- Systemic disease or renal pathology Proteinuria
Functional Proteinuria
- Not associated with renal damage
- Accidental or false proteinuria
- Occurs due to mixing of urine with proteinous fluids (pus, blood, vaginal discharge)
- Physiological proteinuria
- Less than 0.5 gm/24 hrs
- Associated with fever, exposure to heat or cold, emotional stress, and late pregnancy
- Postural (orthostatic) proteinuria
- Associated with upright position or sitting for a long time
- Intermittent proteinuria that disappears when lying down
Systemic Disease or Renal Pathology Proteinuria
- Not due to primary renal disease
- Fever and toxic conditions
- Venous congestion
- Renal hypoxia
- Hypertension
- Myxedema (hypothyroidism)
- Bence Jones protein
- Primarily kidney disease
- Glomerulonephritis
- Nephrotic syndrome (primary and secondary)
- Destructive parenchymal lesions (tumor, infection)
- Protein added to urine at a point farther down the urinary tract from the renal parenchyma
- Infection of the renal pelvis or ureter
- Cystitis
- Urethritis or prostatitis
- Contamination with vaginal secretions
Test for Urinary Protein
- Precipitation or turbidimetric test
- Principle: protein is precipitated or coagulated out of urine
- Tests include:
- Robert's Test (ring tests)
- Heller's Test (ring tests)
- Sulphosalicylic Acid Test (non-ring tests)
- Heat and Acetic Acid Test (non-ring tests)
Robert's Test
- Principle: protein is precipitated using concentrated Nitric acid (HNO3), forming a white compact ring
- Place 3-5 ml urine in a test tube
- Add 3 ml of Robert's reagent below the urine
- A white ring at the zone of contact indicates a positive test
- Read the ring within 3 minutes
- Report results based on the type of ring formed
Heller's Test
- Same principle as Robert's Test
- Heller's reagent is concentrated nitric acid
- Same procedure as Robert's test
Sulphosalicylic Acid Test
- Principle: Sulphosalicylic acid solution (20%) precipitates any protein in urine
- More sensitive and reliable than heat method
- Detects 5 to 10 mg/dl of protein in urine
- Take 2 ml of centrifuged (clear) urine in a test tube
- Add equal amount of Sulphosalicylic acid reagent
- Shake gently and let stand for 10 minutes
- Note the degree of turbidity against a dark background
- Grade and report as a non-ring test
- Interpretation: report based on turbidity
Heat and Acetic Acid Test
- Principle: protein precipitates by heat
- Fill a test tube with clear urine and heat the upper portion for 2 minutes
- Compare the turbidity with known standards
- If turbidity is present, it may be due to phosphates, carbonates, or protein
- Estimate the concentration of protein in the unknown urine
- If unknown urine contains more than 100mg/dl protein, dilute and repeat
Quantitative 24 Hour Protein Determinations
- Esbach’s Test
- Measure the total volume and filter some of the urine
- Perform qualitative protein test (Robert's or strip test)
- Make dilution based on qualitative test results
- Measure pH of urine and adjust if necessary
- Add pumice powder to the 0.5 mark of the Esbach's tube
- Add urine to the “U” mark
- Add Esbach’s reagent to the “R” mark
- Mix slowly by inversion 10 times
- Wait 30 minutes and read the highest point of the column
- The result is in grams per liter of protein in the urine
- Multiply by the dilution factor if diluted
- Calculate and record the g % and g / 24 hrs
Clinical Significance of Proteinuria
- Proteinuria: >6-8gm/l indicates renal damage
- A positive protein test may be correlated with casts
- Timely diagnosis and treatment are essential to prevent permanent kidney damage
- Presence of protein, leukocytes, and bacteria in urine suggests urinary tract infection
Bence - Jones Protein
- Abnormal low molecular weight globulin consisting of light chains of immunoglobulin
- Contains amino acids except methionine
- Found in urine of patients with multiple myeloma, a malignant disease of plasma cells affecting bone
- Incidence of Bence-Jones proteinuria in multiple myeloma is 50% to 80%
Heat test to screen Bence -Jones Protein
- Principle: Bence Jones protein coagulates when heated to 40 to 600C and partially/wholly re-dissolves on boiling
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Description
This quiz covers the various testing methods for glucose, including the test-tape and Diastix reagent strip. You'll explore the principles, procedures, and indicators used in these tests. Test your knowledge on how glucose is detected in urine samples.
