3.3 PHYSICAL EXAMINATION OF URINE - SPECIFIC GRAVITY AND ODOR Flashcards

1
Q

Refractometry principle

A

Refractive index

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2
Q

Osmolality principle

A

Changes in colligative properties by
particle number

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3
Q

Reagent strip principle

A

pKa changes of a polyelectrolyte by ions present

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4
Q

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

A

1.010

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5
Q

What term describes urine with a specific gravity of 1.010?

A

Isosthenuric

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6
Q

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

A

Hyposthenuric (below 1.010) and hypersthenuric (above 1.010)

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7
Q

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

A

Approximately 1.002 to 1.035

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8
Q

What is specific gravity a measure of in urine?

A

The density of dissolved chemicals in the specimen

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9
Q

How does the size of molecules affect specific gravity readings?

A

Large molecules contribute more to the reading than small molecules.

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10
Q

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

A

Refractometer

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11
Q

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

A

Chemical reagent strips and osmolality.

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12
Q

What does refractometry measure in a specimen?

A

Concentration of dissolved particles

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13
Q

What does refractive index compare?

A

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

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14
Q

What specific gravity reading is considered abnormally high?

A

Above 1.040

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15
Q

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

A

IV pyelogram or high-molecular-weight IV fluids

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16
Q

How does a refractometer determine specific gravity?

A

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

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17
Q

What is the volume of specimen needed for a refractometer?

A

One or two drops

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18
Q

What temperature range does the refractometer automatically compensate for?

A

15°C to 38°C

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19
Q

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

A

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

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20
Q

What should distilled water read on a calibrated refractometer?

A

1.000

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21
Q

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

A

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

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22
Q

What does osmolality measure?

A

Number of particles present in a solution

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23
Q

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

A

Sodium and chloride

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24
Q

What is an osmole defined as?

A

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

25
Q

How much glucose is contained in 1 osmole?

A

180 g per osmole

26
Q

What is the difference between osmolality and osmolarity?

A

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

27
Q

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

A

Milliosmole (mOsm)

28
Q

What colligative properties change when solute is dissolved in solvent?

A

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

29
Q

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

A

Osmometer

30
Q

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

A

Freezing-point depression

31
Q

Why is measuring osmolality important in urine analysis?

A

It provides a more representative measure of renal concentrating ability.

32
Q

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.

A

Urinometer

33
Q

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

A

Buoyancy

34
Q

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

A

Change in pH

35
Q

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

A

Blue to yellow

36
Q

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

A

Bromothymol blue

37
Q

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

A

Comparison with a color chart

38
Q

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

A

Polyelectrolyte

39
Q

What principle does harmonic oscillation densitometry rely on?

A

Frequency change of sound waves in relation to solution density

40
Q

Normal pure water point freezing point

A

0°C

41
Q

Normal pure water point boiling point

A

100°C

42
Q

Normal pure water point vapor pressure

A

2.38 mm Hg at
25°C

43
Q

Normal pure water point osmotic pressure

A

0 mm Hg

44
Q

Effect if 1 mole of solute in the freezing point

A

Lowered 1.86°C

45
Q

Effect if 1 mole of solute in the vapor pressure

A

Lowered 0.3 mm
Hg at 25°C

46
Q

Effect if 1 mole of solute in the boiling point

A

Raised 0.52°C

47
Q

Effect if 1 mole of solute in the osmotic pressure

A

Increased 1.7 ×
109 mm Hg

48
Q

Normal urine odor

A

aromatic

49
Q

Bacterial decomposition, urinary tract
infection odor

A

Foul, ammonialike

50
Q

Ketones (diabetes mellitus,
starvation, vomiting) odor

A

Fruity, sweet

51
Q

Maple syrup urine disease odor

A

Maple syrup

52
Q

cause of mousy odor of urine

A

Phenylketonuria

53
Q

Rancid urine cause

A

Tyrosinemia

54
Q

Sweaty feet urine odor cause

A

Isovaleric acidemia

55
Q

Cabbage urine odor cause

A

Methionine malabsorption

56
Q

Bleach urine odor is caused by

A

contamination

57
Q

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

A

Breakdown of urea

58
Q

Which foods can cause unusual or pungent odors in urine?

A

Onions, garlic, and asparagus