6/5/25 Renal Labs and Urinalysis

Question 1

Define GFR (glomerular filtration rate).

Answer 1

The sum filtration rates of all a person’s functioning nephrons

Question 2

What do we use a GFR for?

Answer 2

Detect and diagnose CKD
Detect AKI
To see if dialysis is needed
To adjust medication dose
Evaluate fitness for kidney donation

Question 3

What medications are nephrotoxic medications?

Answer 3

NSAIDS (ibuprofen) and some antibiotics

Question 4

True or False: Kidneys can regenerate nephrons.

Answer 4

False

Question 5

What causes kidney failure?

Answer 5

Diabetes
Hypertension
Glomerular disease
Congenital kidney problems

Question 6

What labs can help us determine kidney function?

Answer 6

GFR
Serum Creat
Creat Clearance
BUN

Question 7

What affect does age have on GFR?

Answer 7

GFR decreases 10% each decade beginning at age 40

Question 8

True or false: Males have a higher GFR than women

Answer 8

True

Question 9

What is used to calculate GFR?

Answer 9

serum creat, age, sex, body mass

Question 10

What is creatinine?

Answer 10

a waste product that is produced at a regular rate in muscle tissue during the process of normal muscle metabolism

Question 11

How is creatinine formed?

Answer 11

Phosphocreatine in the muscle is broken down into creatine and inorganic phosphorus. Creatine is then converted to creatinine

Question 12

Creatinine is excreted entirely by the _______.

Answer 12

Kidney

Question 13

Describe the relationship between serum creat and GFR.

Answer 13

Inverse relationship. For every 2x increase of Creat, GFR decreases by 50%

Example: creatinine going from 0.5 to 1.0 means the GFR would decrease by 50%

Question 14

What affect does muscle mass have on creatinine?

Answer 14

High muscle means high creat

Question 15

What affect does age have on creatinine?

Answer 15

Older people have lower creat

Question 16

What affect does diet have on creatinine?

Answer 16

High protein diet means higher creatinine

Question 17

Can we evaluate creatinine only to estimate kidney function?

Answer 17

We can, but it gives only a rough estimate. GFR is more accurate.

Question 18

Can a creatinine be normal during kidney dysfunction?

Answer 18

Yes

Question 19

What is creatinine clearance?

Answer 19

A measure of the GFR

Question 20

Normal creatinine clearance

Answer 20

100 mL/min

Question 21

What is creatinine clearance dependent on?

Answer 21

Age and sex, body mass

Question 22

What are the 2 ways creatinine clearance can be calculated?

Answer 22

Directly or indirectly

Question 23

How can creatinine clearance be indirectly measured?

Answer 23

Test serum creatinine and use the corkcroft-gualt equation (includes age, mass, and sex)

Question 24

What type of creatinine clearance is the standard for drug dosing?

Answer 24

Indirect measurement of creatinine clearance

Question 25

What organ secretes and absorbs BUN?

Answer 25

Kidneys

Question 26

What is BUN a byproduct of?

Answer 26

Protein metabolism

Question 27

BUN is _____ related to the metabolic function of the liver. directly or indirectly

Answer 27

Directly

Question 28

What rises faster during dehydration: BUN or creatinine?

Answer 28

BUN

Question 29

What is azotemia? Is it symptomatic or asymptomatic?

Answer 29

Increase in nitrogenous waste products (urea and creatinine). It is asymptomatic

Question 30

What is uremia?

Answer 30

Symptomatic azotemia

Question 31

What BUN/Cr ratio indicates pre-renal azotemia?

Answer 31

>20:1

Question 32

What would the BUN be in pre-renal azotemia?

Answer 32

Increased (reabsorption is increased)

Question 33

What can cause pre-renal azotemia?

Answer 33

Hypotension, DEHYDRATION obstruction

Question 34

What is the BUN/Cr ratio for intra-renal azotemia?

Answer 34

<10:1

Question 35

What would the BUN be in intra-renal azotemia?

Answer 35

Decreased (renal damage reduces reabsorption)

Question 36

What can cause intra-renal azotemia?

Answer 36

CKD

Question 37

What is the BUN/Cr ratio for post-renal azotemia?

Answer 37

10-20:1 This is the normal range

Question 38

What would the BUN be in post-renal azotemia?

Answer 38

Normal

Question 39

What can cause post-renal azotemia?

Answer 39

BPH, kidney stones

Question 40

What are the types or urine collection?

Answer 40

Random 24 hour Midstream CC 1st voided

Question 41

Gross evaluation of urine

Answer 41

Color, clarity, smell

Question 42

Urine dipstick

Answer 42

Glucose, bili, ketones, SG, blood, pH, protein, uro, nitrites, leukocyte esterase

Question 43

Microscopic

Answer 43

Blood, WBC, bacteria, casts, crystals, epithelial cells

Question 44

Define urine SG

Answer 44

Determined by the number and size of particles in urine

Question 45

Define urine osmolality

Answer 45

Determined by the number of particles in the urine

Question 46

Causes of low SG

Answer 46

Diuretic use Diabetes insipidus Hypoaldosteronism Impaired renal fxn

Question 47

Causes of high SG

Answer 47

Glucosuria SIADH Proteinuria

Question 48

What is the normal albumin level excreted in one day?

Answer 48

<20 mg/day

Question 49

What is the protein concentration in microalbuminuria?

Answer 49

30-300 mg/day

Question 50

What is the protein concentration in macroalbuminuria?

Answer 50

>300 mg/day

Question 51

Where is glucose typically reabsorbed at?

Answer 51

PCT

Question 52

What is the plasma glucose threshold?

Answer 52

180-200 mg/day Glucose will spill over into the urine if this threshold is exceeded.

Question 53

What does the blood pad on the urine dipstick detect?

Answer 53

Hematuria, hemoglobinuria, myoglobinuria

Question 54

Define gross hematuria

Answer 54

Blood in urine you can see with your eyes

Question 55

Define microscopic hematuria

Answer 55

Blood in urine you need a microscope to see

Question 56

Causes of blood in the urine

Answer 56

Renal disease Cystitis Bladder cancer Prostatitis Prostate cancer Anticoagulants Stones Trauma Exercise Mensturation

Question 57

Up to ____% of patients with gross hematuria have a urinary tract malignancy.

Answer 57

20%

Question 58

What does a pos nitrite strip mean/indicate?

Answer 58

Bacteria present that convert nitrates to nitrites. UTI

Question 59

What does the leukocyte esterase pad detect? What is it a sign of?

Answer 59

WBCs. UTI

Question 60

Is the bilirubin in the urine conjugated or unconjugated?

Answer 60

CO\onjugated (must be conjugated to be water soluble)

Question 61

What is urobilinogen?

Answer 61

End product of bilirubin after metabolized by the intestines. A small amount in the urine is normal