7. Clinical Assessment of Renal Function

Question 1

creatinine: what is it, what does its serum level depend on?

Answer 1

waste product from muscle

depends on muscle mass, age, sex

Question 2

creatinine: how long does it take for the serum level to rise after renal injury?

Answer 2

after acute renal inj, can take ~5d for serum creatinine to rise

Question 3

if an elderly patient has a normal serum creatinine, what should I be thinking?

Answer 3

may be normal; may also be high for this patient given that elderly usually have low muscle mass

Question 4

we can use creatinine clearance to estimate what?

Answer 4

creatinine clearance correlates with GFR: urine creatinine levels can therefore estimate GFR. need a 24 hr urine sample

Question 5

when GFR decreases, how will BUN and serum creatinine levels change?

Answer 5

both will rise

Question 6

if the BUN to serum creatinine ratio is >20:1 (very high) what is going on?

Answer 6

prerenal azotemia (hypovolemic injury to kidney). causes BUN to rise more than creatinine

Question 7

how are serum and urine creatinine levels used to estimate GFR?

Answer 7

i have no effing clue but i need to figure it out

Question 8

what is the spectrum of GFRs encompassed by Stage 1 thru 5 chronic kidney disease?

Answer 8

Stage 1 GFR: >90

Stage 5 GFR <15 or dialysis

Question 9

anuria defined as how much urine volume per day?

Answer 9

<50 cc. acute renal failure, possibly life-threatening

Question 10

oliguria defined as how much urine volume per day?

Answer 10

<500 cc. acute renal failure, possibly life-threatening

Question 11

normal range of urine production?

Answer 11

500-3000cc/day

Question 12

definition of polyuria? a few causes?

Answer 12

> 3000cc/day. causes: polydipsia, diabetes insipidus, DM

Question 13

urine dipstick: what do ketones indicate?

Answer 13

possible DKA, if high glucose as well

Question 14

urine dipstick: if proteins are low but other tests indicate high urine proteins, what is possible?

Answer 14

Bence-Jones proteins. suggest multiple myeloma

Question 15

urine dipstick: what does specific gravity indicate?

Answer 15

concentration of urine: dilute = 1.001, concentrated = 1.040. isosthenuria = 1.015

Question 16

what is isosthenuria/what does it indicate?

Answer 16

urine is isosmotic with plasma. possible renal insufficiency (not concentrating urine)

Question 17

nephritic syndrome: a few findings? what processes does it indicate?

Answer 17

Hematuria
Oliguria
Azotemia (incr. urea, creatinine, N-rich compounds)
HTN

AHHO

Sx: edema, flank pain, incr creatinine.
indicates that problem is on the capillary lumen side (in contact with bloodstream)

Question 18

nephrotic syndrome: a few findings? what processes does it indicate?

Answer 18

proteinuria, edema, hypoalbuminemia, hyperlipidemia.

PEHHing proteins

indicates lesion of epithelial cells and/or glo BM. not in contact with bloodstream –> no hematuria

Question 19

acanthocytes: definition, what do they indicate?

Answer 19

RBCs that crossed the basement membrane and were damaged in transit. indicate glomerularnephritis

Question 20

lipids in the urine indicates what?

Answer 20

nephrotic syndrome. will appear as oval fat bodies, fatty casts, cholesterol crystals. Fatty casts look like RBC casts but particles vary in size

Question 21

cysteine crystals: appearance? indicate what?

Answer 21

hexagonal crystals. pathognomic for kidney stones

Question 22

RBC casts indicate what?

Answer 22

glomerulonephritis, inflammation

Question 23

Fatty casts indicate what?

Answer 23

nephrotic conditions. liver increases albumin production to make up for loss, also upregs production of lipoproteins –> lipiduria

Question 24

WBC casts indicate what?

Answer 24

inflammation of tubules and interstitium of kidney

Question 25

waxy/granular casts indicate what?

Answer 25

various stages of degeneration of casts, therefore nonspecific. can ben seen in a variety of conditions

Question 26

muddy brown casts: made of what? indicate what?

Answer 26

acute tubular necrosis (ATN). made of tubular epithelial cells

Question 27

butterfly rash on face indicates what condition?

Answer 27

lupus

Question 28

hemoptysis and pulmonary infiltrates indicate what condition?

Answer 28

Goodpasture’s (renal/pulm condition)

Question 29

deafness may indicate what disease?

Answer 29

Alport’s

Question 30

Ash leaf spots may indicate what disease?

Answer 30

tuberous sclerosis