chapter 6

Question 1

what gives urine yellow color

Answer 1

urochrome

Question 2

what does dark yellow urine mean

Answer 2

concentrated urine (dehydration)

Question 3

what does pale urine mean

Answer 3

diluted urine (hydrated)

Question 4

substances that can change color of urine

Answer 4

1. blood (myoglobin) –> red
2. bilirubin –> orangish
3. porphyrins –> purple reddish
4. melanin –> brown
5. indican –> blue
6. homogentisic acid –> black

Question 5

foam

Answer 5

normal urine will have foam when shaken but will dissipate

Question 6

what causes stable white foam

Answer 6

large amounts of albumin in urine

Question 7

what causes yellow foam in urine

Answer 7

increased amounts of bilirubin

Question 8

clarity of urine

Answer 8

normal urine is clear

Question 9

causes of cloudiness

Answer 9

1. contamination from skin or vaginal secretions
2. precipitation of dissolved solutes
3. rbc, wbc, epithelial cells

Question 10

odor

Answer 10

normal urine has a smell
–> becomes more odorous due to conversion from urea to ammonia

Question 11

disorders that can cause unusual odor of urine

Answer 11

ketones (fruity) and amino acid

Question 12

concentration

Answer 12

normal urine consists of 94% water and 6% solutes
–> color is an indicator of concentration

Question 13

specific gravity

Answer 13

concentration in terms of density
(greater density = greater specific gravity)

Question 14

refractometry

Answer 14

indirect method based on refractive index of light
–> increase in solutes = decrease in light velocity
–> measures all solutes

Question 15

3 factors that affect refractive index of a solution

Answer 15

1. wavelength used (typically 589)
2. temperature of solution
3. concentration of solution

Question 16

reagent strip method

Answer 16

indirect colorimetric estimation of urine density
–> does not measure nonionic large molecular weight solutes
–> does not measure true density

Question 17

how does reagent strip work

Answer 17

when strip is immersed in urine, protons from polyelectrolyte in proportion to ionic concentration thus changing color of pad

Question 18

osmolality

Answer 18

normal urine values 275 - 900

Question 19

uses of osmolality

Answer 19

evaluating renal concentrating ability, monitor renal diseases, monitor fluid and electrolyte balance

Question 20

freezing point osmometry

Answer 20

detects presence of volatile solutes
–> adding 1 osmole of solute to 1 kg of water decreases freezing point by 1.86

Question 21

volume

Answer 21

normal volume of urine is 600 to 1800

Question 22

isothenuria

Answer 22

inability of kidneys to change specific gravity of plasma ultrafiltrate