Renal Physiology, Handout 1

Front 1

What is the significant method to clear blood of drugs and toxins?

Back 1

secretion into tubular fluid. because usually they are protein bound

Front 2

What is GFR?

Back 2

Glomerular Filtration Rate.
What volume of plasma fluid do the two kidneys normally filter per minute into their proximal tubule?

Front 3

What is inulin?

Back 3

a compound that physiologists used to calculate the GFR. It is neither secreted or reabsorbed. so the amt inulin filtered= amt inulin excreted in urine

Front 4

What is the total volume of plasma flowing through the glomerular capillaries of both kidneys called?

Back 4

ERPF-
Effective Renal Plasma Flow

Front 5

What is ERPF and PAH?

Back 5

Effective Renal Plasma Flow,
and Para-aminohippuric acid. amt in plasma=amt in urine because of secretion and filtration.

Front 6

What is TRPF?

Back 6

Total Renal Plasma Flow
only 90% of plasma go thru the gomeruli. 10% goes thru other renal vessels. (vasa recta)

Front 7

How do you get the TRPF?

Back 7

Divide the ERPF (plasma going through the glomeruli) by .9

Front 8

FF

Back 8

Filtration Fraction.
We have the total volume of plasma that goes thru the kidneys together, and the volume that is filtered. so
GFR/TRPF. 20% of plasma is filtered per min by two kidneys to produce early urine

Front 9

Define Renal Clearance.

Back 9

The milliliters of plasma that have been cleared of a substance.

Front 10

What is the formula for Renal Clearance?

Back 10

Cx = Ux V/ Px

Front 11

What is the advantage of creatinine clearance over renal clearance?

Back 11

Renal clearance is based on pt age, the drug, weight, gender etc.
And we don't know all of the expected renal clearances of all drugs.

Front 12

What is phosphocreatine?

Back 12

phosphocreatine is broken down by the body into creatinine. It is found in skeletal muscle and is used to form extra ATP.

Front 13

What is creatinine clearance a good indication of? and why?

Back 13

It is a pretty accurate measure of GFR. because creatinine is freely filtered, not reabsorbed.

Front 14

Why does creatinine clearance slightly overestimate the GFR?

Back 14

It is very slightly secreted, and since there is slightly more creatinine in the urine than the total amt filtered, it overestimates GFR.
Early renal failure (dec'd GFR) may be missed if just looking at CC!

Front 15

What are some symptoms of decreased GFR?

Back 15

dec'd urine production (anuria or oliguria)
dec'd CC > inc'd plasma creatinine
dec'd urea clearance > inc'd BUN (blood urea nitrogen)

Front 16

What is the volume of normal urine production?
Oliguria?
Anuria?
Polyuria?

Back 16

Normal: 700-2000 ml
Oliguria: <500
Anuria: <100
Polyuria:>2500

Front 17

Define azotemia.

Back 17

nitrogenous wastes, creatinine, and BUN in plasma.
Asymptomatic renal failure

Front 18

What is the Cockcroft & Gault equation used for?

Back 18

Estimated CC for infants/elderly

Front 19

What is normal Creatinine clearance?

Back 19

for simplicity, 75-125 ml/min

Front 20

What are the three broad categories of early renal failure (azotemia)?

Back 20

pre renal azotemia
renal azotemia (intrinsic)
post renal azotemia

Front 21

Describe some things that can cause pre-renal azotemia.

Back 21

Stenosis of renal artery
Systemic Hypotension (kidney not getting enough flow)
Edematous states (swelling somewhere)

Front 22

What can cause hypotension?

Back 22

dehydration, hemorrhage, vomitting/diarrhea, diuretics

Front 23

What could cause an edematous state?

Back 23

CHF
Cirrhosis>causes ascites
nephrotic syndrome (massive proteinuria)

Front 24

What is Renal Azotemia?

Back 24

Intrinsic. THere is actually a problem with the nephron structures themselves or intrarenal arteries

Front 25

What can cause renal azotemia?

Back 25

Chronic HTN, (diabetes)
Glomerulonephritis
acute tubular necrosis (ATN)

Front 26

What are aminoglycosides? examples?

Back 26

nephrotoxic drugs,
steptomycin, amikacin

Front 27

What can cause post renal azotemia?

Back 27

a renal obstruction (calcium or uric acid stones)
stone in ureter (urolithiasis)
chemo agents (produce uric acid)
BPH (benign prostatic hypertrophy)>can't pee

Front 28

Why may chemo agents lead to azotemia?

Back 28

because they release components that are metabolized into uric acid

Front 29

What does FEna mean?

Back 29

Fractional Excretion of Sodium. Na is the most important determinant of body fluid volume

Front 30

What is the formula for FEna?

Back 30

Una x Pcre
FEna= -------------- x 100
Pna x Ucre

Front 31

What is the normalish FEna?

Back 31

excess Na= 5 %
little Na = 0.1%
But under 1%, it is a good indicator that the kidney is conserving sodium

Front 32

What would a FEna of less than 1% indicate?

Back 32

Pre renal azotemia

Front 33

What would a FEna of greater than 4% indicate?

Back 33

post renal azotemia

Front 34

How do you calculate a FEna?

Back 34

ex. Pna = 140 mEq/L
Una= 20mEq/L
Ucre= 15mg/dl
Pcre= 1 mg/dl
IGNORE units, plug in.

Front 35

What is BUN and what is normal?

Back 35

Blood urea nitrogen. Normal ratio is 10-15 BUN/Pcre.
this will rise to 20-30 in prerenal azotemia.

Front 36

Why is BUN an indicator of azotemia?

Back 36

Because the reabsorption of Na from the tubular fluid is linked to reabsorption of urea from the same tubular fluid.

Front 37

Explain why the BUN/Pcre ratio may return to normal if the patient is still sick?

Back 37

- tubular damage that prevents increased reabsorption of Na cuasing less reabsorption of urea.
-worse renal failure, in which creatinine clearance decreases, so Pcre increases.

Front 38

What color blood comes from the lower urinary tract?

Back 38

from ureters down, it will be red
From upper tract, it will be tea colored or rust colored.