renal assesment

Question 1

function of nephron

Answer 1

regulation of water, electrolyte and acid base balance

excretion of products of protein and nucleic acid metabolism

Question 2

what three ways do we evaluate renal function?

Answer 2

1. eGFR
2. BUN:Creatinine ratio
3. urinalysis

Question 3

what do you need to analyze eGFR?

Answer 3

you need to analyze eGFR?
age
gender
race
serum [creatinine]

Question 4

what is a normal value for eGFR?

Answer 4

greater than or equal to 60 ml/min/1.73m^2

Question 5

what are the sources of urine nitrogen?

Answer 5

deamination of proteins
enteric bacteria waste product
protein catabolized in a GI bleed

Question 6

when BUN and creatinine increase what happens to kidney function?

Answer 6

decrease

Question 7

what is a normal BUN:Creatinine ratio

Answer 7

10:1 to 20:1

Question 8

what constitutes the best urine specimen?

Answer 8

first voided urine
mid-stream clean catch

usually b/c its concentrated so demonstrates ability of kidneys to concentrate and also concentrates infections

Question 9

what can red urine indicate?

Answer 9

blood (menstrual)
beets
meds (pyridium - analgesic for relief of UTI pain)

Question 10

what can orange urine indicate?

Answer 10

bilirubin

rifampicin (antibiotic)

Question 11

what does black urine indicate?

Answer 11

alkaptonuria

Question 12

what does yellow-brown/green-brown urine indicate?

Answer 12

bilirubin

Question 13

what is alkaptonuria?

Answer 13

enzyme deficiency of homogentistic oxidase (required for the degradation of tyrosine)

Question 14

what is another name for homogentisic acid?

Answer 14

alkapton

Question 15

when does the urine darken in alkaptonuria?

Answer 15

upon standing

Question 16

what can cause cloudy urine?

Answer 16

crystals
bacteria
rbc
pyuria (pus)

Question 17

what does the urine specific gravity tell us?

Answer 17

renal concentrating ability

Question 18

what is the RR for urine specific gravity?

Answer 18

1.003-1.035

Question 19

what are the pathogenic causes of LOW urine specific gravity?

Answer 19

psychogenic polydipsia
ADH deficiency (central DI)
ADH resistance (nephrogenic DI)

Question 20

what are the pathogenic causes of high urine specific gravity?

Answer 20

decreased renal perfusion
excess ADH
osmotic substances present in urine

Question 21

is the urine specific gravity reliable as an index of a patient’s fluid status?

Answer 21

no

Question 22

what is the chemical principle behind urine specific gravity testing?

Answer 22

H+ interacts with bromthymol blue indicator to form a colored complex

Question 23

what is the PCT’s role in urine pH maintenance? what is the role of the DCT?

Answer 23

PCT - reabsorb HCO3-

DCT - secrete H+ and generate HCO3-

Question 24

what are common causes of acidic urine?

Answer 24

DKA (ketones are acidic and FA buildup)

drugs that affect the transport of electrolytes (spironolactone - CHF, trimethoprim - antibiotic, heparin)

Question 25

what are common causes of alkaline urine?

Answer 25

bacteria (usually increase pH as they break down urea in the urine to ammonia)

stones (calcium carbonate, calciumphosphate, magnesium phosphate)

Question 26

what is alkaline urine?

Answer 26

> 8 pH

Question 27

what is acidic urine?

Answer 27

<4.5

Question 28

what causes glucosuria?

Answer 28

DM

gestational diabetes

Question 29

what can cause bilirubin to appear in urine?

Answer 29

liver damage
obstructed bile ducts
(both allow conjugated bilirubin to enter the circulation and ultimately appear in urine)
if jaundice is due to red cell destruction

Question 30

when does urobilinogen increase?

Answer 30

in the presence of hemolytic processes such as hemolytic anemia

Question 31

what is urobilinogen?

Answer 31

a byproduct of hemoglobin breakdown

produced in intestinal tract as a result of the action of bacteria on bilirubin

Question 32

when do ketones appear in the urine?

Answer 32

DKA
Starvation
increased lipolysis causing over production of FFA

Question 33

when does protein appear in the urine?

Answer 33

glomerular damage resulting in “leaky” glomeruli
Presence in urine of cells or blood
check if urine is also positive for blood, WBC, UTI (culture)

Question 34

when does blood appear in the urine?

Answer 34

malignancy
UTI
menstruation

presence in urine of large numbers of RBCs establishes diagnosis of hematuria

Question 35

what two things can cause hematuria?

Answer 35

hemoglobinuria (lysis of RBC from things such as intravascular hemolysis)

myoglobinuria (muscle trauma or disease)

Question 36

when does nitrite appear in the urine?

Answer 36

infection with gram negative bacteria

*depends on conversion of nitrate to nitrite by the action of bacteria that contain the necessary reductase

**positive result indicates a UTI

Question 37

what is the significance of leukocyte esterase in the urine?

Answer 37

acute inflammation and presence of UTI

Question 38

per high power field (HPF) it is normal to see how many erythrocytes? what is pathological?

Answer 38

normal is 1-2

path is > 3

Question 39

what is a pathological value of bacteria per HPF?

Answer 39

more than 10

Question 40

what is a pathological value of yeasts per HPF?

Answer 40

more than 10 - most likely a contaminant, but should correlate with clinical picture

Question 41

what are casts?

Answer 41

when mucoproteins screted by tubule cells encase RBCs or endothelial cells

(tamm-horsfall mucoproteins)

Question 42

crystals seen on microscopic examination can come from what types of deposits?

Answer 42

urate (ammonium biurate, uric acid)
triple phosphate
calcium oxalate
amino acids (cysteine, leucine, tyrosine)
sulfonamides