32 Questions
What is the characteristic of urine in cases of porphyria?
Red-brown color in acidic urine after standing
What is the characteristic of black urine in relation to nitroprusside and ferric chloride?
Reacts with both nitroprusside and ferric chloride
What is the term for urine with many particulates, where the print is blurred when seen through?
Cloudy
What is a non-pathologic cause of turbidity in urine?
Squamous epithelial cells and mucus
What is the term for urine that is transparent and has no visible particulates?
Clear
What is an antihypertensive associated with black urine?
Not mentioned
What is the primary pigment responsible for the yellow color of urine?
Urochrome
What is the significance of measuring specific gravity in the routine analysis of urine?
To provide information about the kidney's ability to concentrate urine
Which of the following methods is NOT used to determine specific gravity?
Microscopy
What is the possible cause of cloudy red urine?
Hematuria or hemoglobinuria
What is the primary measure of refractometry?
Refractive index
What is the advantage of measuring specific gravity using a reagent strip and osmolality?
It is more convenient and provides a more accurate measurement
What is the principle behind osmolality measurements?
Changes in colligative properties by particle number
What is the normal color of urine in a laboratory?
Pale yellow, yellow, and dark yellow
What is the advantage of using refractometry to measure specific gravity?
It requires a small volume of specimen (1-2 drops)
What is a common cause of a colorless urine specimen?
Random specimen
What is the term for a specific gravity of 1.010?
Isosthenuric
Which of the following can cause a dark yellow urine color?
May be first morning specimen
What is the principle behind reagent strip measurements?
pKa changes of a polyelectrolyte by ions present
What is affected by the type of particles present in a solution?
Osmolality
What is the cause of a yellow-green urine color?
Colored foam in acidic urine and false-negative chemical test results for bilirubin
Which of the following can cause a blue-green urine color?
Antidepressant, Muscle relaxant, Bacterial infections, intestinal disorders
What can be obtained by measuring osmolarity?
A measure of renal concentrating ability
What is the color change observed on a reagent strip as the specific gravity increases?
From blue to green to yellow
What is the cause of a pink urine color?
Cloudy urine with positive chemical test results for blood
What is the cause of a port wine-colored urine?
Porphyrins excreted in the urine
What is the effect of increased concentration of urine on pH?
Decreased pH
What type of odor is characteristic of freshly voided urine?
Faint aromatic
Which of the following is a cause of foul, ammonia-like odor in urine?
Bacterial decomposition, urinary tract infection
What is the purpose of bromthymol blue on the reagent pad?
To measure pH
What is the characteristic of urine in cases of maple syrup urine disease?
Fruity, sweet odor
What is the characteristic of urine in cases of isovaleric acidemia?
Sweaty feet odor
Study Notes
Urine Color
- The yellow color of urine is caused by the presence of urochrome, which increases in thyroid conditions, fasting states, and when left at room temperature.
- Other pigments that can affect urine color include uroerythrin, urobilin, bilirubin, and biliverdin.
- Abnormal urine colors and their possible causes:
- Colorless: commonly observed with random specimens
- Pale yellow: increased 24-hour volume, low specific gravity, or recent fluid consumption
- Dark yellow: first morning specimen, fever, burns, or antibiotic administration
- Orange-yellow: certain medications (e.g., Phenazopyridine)
- Yellow-green: acidic urine with a positive chemical test result for bilirubin
- Green: positive urine culture, RBCs visible microscopically, or intravascular hemolysis
- Blue-green: certain medications, bacterial infections, or intestinal disorders
- Pink: cloudy urine with a positive chemical test result for blood
- Red: clear urine with a positive chemical test result for blood or intravascular hemolysis
- Port wine: porphyrins excreted in the urine (porphyria)
- Red-brown: acidic urine with a positive chemical test result for blood
- Brown: alkaline urine with a positive chemical test result for blood
- Black: urine darkens on standing and reacts with nitroprusside and ferric chloride
Urine Clarity
- Cloudy urine: many particulates, print blurred through urine
- Turbid urine: print cannot be seen through urine
- Milky urine: may precipitate or be clotted
- Non-pathologic turbidity: presence of squamous epithelial cells and mucus, semen, fecal contamination, radiographic contrast media, talcum powder, or vaginal creams
- Pathologic turbidity: RBCs, WBCs, bacteria, or yeast
Specific Gravity
- Measure of the density of dissolved chemicals in the specimen
- Isosthenuric: specific gravity of 1.010
- Hyposthenuric: specific gravity below 1.010
- Hypersthenuric: specific gravity above 1.010
- Methods of measuring specific gravity:
- Refractometry: measures refractive index
- Osmolality: measures changes in colligative properties by particle number
- Reagent strip: based on pKa changes of a polyelectrolyte by ions present
Refractometry
- Determines the concentration of dissolved particles in a specimen by measuring refractive index
- Requires only a small volume of specimen (1-2 drops)
- Measures the velocity of light in air and the velocity of light in a solution
Osmolality
- Measures the number of solute particles per unit of solvent
- Affected only by the number of particles present
- Can be used to measure renal concentrating ability
Reagent Strip
- Based on the change in pKa of a polyelectrolyte in an alkaline medium
- Indicator bromthymol blue measures the pH
- Increased concentration of urine = increased H+ ions released = decreased pH
Urine Odor
- Normal urine: faint aromatic odor
- Long-standing specimen: odor of ammonia becomes more prominent
- Causes of abnormal urine odor:
- Foul, ammonia-like: bacterial decomposition, urinary tract infection
- Fruity, sweet: ketones (diabetes mellitus, starvation, vomiting)
- Maple syrup: maple syrup urine disease
- Mousy: phenylketonuria
- Rancid: tyrosinemia
- Sweaty feet: isovaleric acidemia
- Cabbage: methionine malabsorption
- Bleach: contamination
This quiz covers the physical examination of urine, including common terminologies, normal urine color, and the significance of different urine characteristics.
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