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P&T Block 5 Renal > L57 > Flashcards

Flashcards in L57 Deck (29)
1

Is Cr or BUN (urea) produced at a constant rate?

Cr
BUN det by protein intake and catabolism: unreliable marker of GFR

2

What happens to Cr as GFR drops?

HYPERBOLIC curve
Large ↓GFR is masked by small changes in Cr

3

What is eGFR?

Estimated GFR
Takes Cr, age, gender, weight and race into account
ONLY use in steady state

4

What lab value is used to stage CKD?

eGFR

5

What is the Cr during CKD stage 1?

eGFR = 90+
Early CKD - Cr may not change at all (L hyperbolic curve)
*Realize small changes = large losses in fxn*
The healthy nephrons hypertrophy to take the load from damaged ones

6

What does Cr tell you in late CKD?

Large shifts in Cr for small changes GFR
R side hyperbolic curve

7

How does the kidney's handling of Na change in CKD?

Goal is the same during healthy or disease: Na in = Na out
See ↑FE Na
FE Na - same Na / less filtered load
You must excrete more of the filtered load because you're now less effective

8

How does a CKD do to adapt to high Na intake?

Can elim the excess Na but takes longer
Leave you in +Na balance = edema

9

What does a CKD kidney do to adapt to low Na?

↓U Na - takes longer
Excess restriction = (-)Na balance -> hypovolemia

10

How does water excretion change in CKD?

Can't max [ ] or dilute
If you can't [ ] urine, you must pee more volume to get the same amt solute out
↑Minimum daily urine vol

11

Why does high urine volume NOT imply good renal fxn in CKD?

B/c less urine [ ] means more volume is need to excrete a normal amt solute

12

Which part of the nephron determines L homeostasis?

CD
All K is reabsorbed at PCT
Therefore depends on the ability to secrete K @ CD

13

Do you become alkalotic or acidemic during CKD progression? 3 reasons why

Metabolic acidosis
1. Can't reclaim bicarb (PCT)
2. Can't NH4 (PCT)
3. Can't generate pH gradient (CD)

14

What is the best measure of kidney H+ secretion?

U NH4 > pH

15

Is the metabolic acidosis during CKD gap or non-gap?

Early: non-gap
Late: gap b/c not excreting titratable acids

16

How does acidemia effect the bones? Treat

Osteodystrophy
+ PO bicarb

17

Why does 1,25 vit D drop as ↓GFR?

B/c kidney does the 1 hydroxylation
Can't make 1,25 vit D = calcitriol
↓Reabsorption of Ca from gut
Fails early in CKD

18

3 normal fxn PTH

1. Release Ca2+ from bone
2. ↑25 -> 1,25 vit D @ kidney
3. ↓Phosphate reabsorption by kidney

19

What are the 2 factors that lead to ↓P Ca in CKD?

↓1,25 vit D - ↓Ca from gut
↓PO4 excretion - ↑ in plasma

20

What are the effects of ↓Ca?

↑PTH
1. ↑Osteoclast = ↑P Ca
2. Reabsorb @ kidney (dysfxn)

21

What is FGF23? How does it effect PTH + phosphate?

Phosphatonin = stim phosphate excretion via urine to raise blood Ca
↓FGF23 in CKD: ↓PTH, ↑phosphate

22

Signs + symptoms of renal osteodystrophy

Pain: low back, hips, knees
Pathologic fx
Pruritis
Vasc + tissue calcification
Rickets + growth retardation - kids

23

What is a negative SE of tissue calcification?

Calciphylaxis = thrombosis + skin necrosis

24

What is osteitis fibrosa cystica? Appearance on XR

PTH excess: bone formation + reabsorption
XR: subperiosteal bone reabsorption

25

Treat osteitis fibrosa cystica

1. ↓Phosphate intake//bind whatever is in diet @ GI
2. +1,25 vit D
3. Ca receptor antag
Extreme: parathyroidectomy

26

What happens if you suppress PTH too much?

Adynamic bone disease - too brittle, can't adapt

27

What is osteomalacia?

Failure to mineralize new osteoid
Artifact of old meds - not as relevant

28

Treat CKD anemia

Recombinant EPO

29

Treat slowly progressing CKD

BP + diabetes/glucose control
ACE I or AGT receptor blockers