3.3 LEC

Question 1

Refractometry principle

Answer 1

Refractive index

Question 2

Osmolality principle

Answer 2

Changes in colligative properties by
particle number

Question 3

Reagent strip principle

Answer 3

pKa changes of a polyelectrolyte by ions present

Question 4

What is the specific gravity of plasma filtrate entering the glomerulus?

Answer 4

1.010

Question 5

What term describes urine with a specific gravity of 1.010?

Answer 5

Isosthenuric

Question 6

What are the terms for urine with specific gravities below and above 1.010?

Answer 6

Hyposthenuric (below 1.010) and hypersthenuric (above 1.010)

Question 7

What is the typical range of specific gravity for normal random urine specimens?

Answer 7

Approximately 1.002 to 1.035

Question 8

What is specific gravity a measure of in urine?

Answer 8

The density of dissolved chemicals in the specimen

Question 9

How does the size of molecules affect specific gravity readings?

Answer 9

Large molecules contribute more to the reading than small molecules.

Question 10

Which method of measuring specific gravity in urinalysis requires correction for substances like glucose and protein?

Answer 10

Refractometer

Question 11

What are the other two methods in use for measuring specific gravity besides the refractometer?

Answer 11

Chemical reagent strips and osmolality.

Question 12

What does refractometry measure in a specimen?

Answer 12

Concentration of dissolved particles

Question 13

What does refractive index compare?

Answer 13

Velocity of light in air with the velocity of light in a solution

Question 14

What specific gravity reading is considered abnormally high?

Answer 14

Above 1.040

Question 15

What can cause urine to have an abnormally high specific gravity?

Answer 15

IV pyelogram or high-molecular-weight IV fluids

Question 16

How does a refractometer determine specific gravity?

Answer 16

By directing light through a prism at a manufacturer-calibrated scale

Question 17

What is the volume of specimen needed for a refractometer?

Answer 17

One or two drops

Question 18

What temperature range does the refractometer automatically compensate for?

Answer 18

15°C to 38°C

Question 19

How much should you subtract from the specific gravity for each gram of protein and glucose present?

Answer 19

0.003 for each gram of protein and 0.004 for each gram of glucose

Question 20

What should distilled water read on a calibrated refractometer?

Answer 20

1.000

Question 21

What specific gravity readings should 5% NaCl and 9% sucrose give on a refractometer?

Answer 21

1.022 ± 0.001 for 5% NaCl and 1.034 ± 0.001 for 9% sucrose.

Question 22

What does osmolality measure?

Answer 22

Number of particles present in a solution

Question 23

Which small molecules are primarily of interest when evaluating renal concentration ability?

Answer 23

Sodium and chloride

Question 24

What is an osmole defined as?

Answer 24

1 g molecular weight of a substance divided by the number of particles it dissociates into

Question 25

How much glucose is contained in 1 osmole?

Answer 25

180 g per osmole

Question 26

What is the difference between osmolality and osmolarity?

Answer 26

Osmolality refers to solute concentration per kg of solvent; osmolarity refers to solute concentration per L of solvent

Question 27

What unit of measure is commonly used in clinical laboratories for osmolality?

Answer 27

Milliosmole (mOsm)

Question 28

What colligative properties change when solute is dissolved in solvent?

Answer 28

Lower freezing point, higher boiling point, increased osmotic pressure, lower vapor pressure

Question 29

What equipment is used to measure osmolality in the urinalysis laboratory?

Answer 29

Osmometer

Question 30

What method does the A2O Advanced Automated Osmometer use to measure osmolality?

Answer 30

Freezing-point depression

Question 31

Why is measuring osmolality important in urine analysis?

Answer 31

It provides a more representative measure of renal concentrating ability.

Question 32

consists of a weighted float attached to a scale that has been calibrated in terms of urine specific gravity. The weighted float displaces a volume of liquid equal to its weight and has been designed to sink to a level of 1.000 in distilled water. The additional mass provided by the dissolved substances in urine causes the float to displace a volume of urine smaller than that of distilled water.

Answer 32

Urinometer

Question 33

What is the principle that allows a urinometer to measure specific gravity?

Answer 33

Buoyancy

Question 34

What does the reagent strip for specific gravity measure in urine?

Answer 34

Change in pH

Question 35

What is the color change of the reagent strip for specific gravity from 1.000 to 1.030?

Answer 35

Blue to yellow

Question 36

Which indicator is used on the reagent strip to measure specific gravity?

Answer 36

Bromothymol blue

Question 37

How are readings for specific gravity determined using the reagent strip?

Answer 37

Comparison with a color chart

Question 38

What type of substance is used in the reagent strip to indicate specific gravity changes?

Answer 38

Polyelectrolyte

Question 39

What principle does harmonic oscillation densitometry rely on?

Answer 39

Frequency change of sound waves in relation to solution density

Question 40

Normal pure water point freezing point

Answer 40

0°C

Question 41

Normal pure water point boiling point

Answer 41

100°C

Question 42

Normal pure water point vapor pressure

Answer 42

2.38 mm Hg at 25°C

Question 43

Normal pure water point osmotic pressure

Answer 43

0 mm Hg

Question 44

Effect if 1 mole of solute in the freezing point

Answer 44

Lowered 1.86°C

Question 45

Effect if 1 mole of solute in the vapor pressure

Answer 45

Lowered 0.3 mm Hg at 25°C

Question 46

Effect if 1 mole of solute in the boiling point

Answer 46

Raised 0.52°C

Question 47

Effect if 1 mole of solute in the osmotic pressure

Answer 47

Increased 1.7 × 109 mm Hg

Question 48

Normal urine odor

Answer 48

aromatic

Question 49

Bacterial decomposition, urinary tract infection odor

Answer 49

Foul, ammonialike

Question 50

Ketones (diabetes mellitus, starvation, vomiting) odor

Answer 50

Fruity, sweet

Question 51

Maple syrup urine disease odor

Answer 51

Maple syrup

Question 52

cause of mousy odor of urine

Answer 52

Phenylketonuria

Question 53

Rancid urine cause

Answer 53

Tyrosinemia

Question 54

Sweaty feet urine odor cause

Answer 54

Isovaleric acidemia

Question 55

Cabbage urine odor cause

Answer 55

Methionine malabsorption

Question 56

Bleach urine odor is caused by

Answer 56

contamination

Question 57

What causes the strong ammonia odor in urine as it stands?

Answer 57

Breakdown of urea

Question 58

Which foods can cause unusual or pungent odors in urine?

Answer 58

Onions, garlic, and asparagus