CKD

Question 1

CKD stages

Answer 1

CKD = permanent reduction in GFR for at least 3 months
- dont get caught up with details

stage 1: >90 - kidney dmg w/ normal GFR
stage 2: 60-89 - kidney damage w/ mild ↓ GFR
stage 3: 30-59 - moderate ↓ GFR
stage 4: 15-29 - severe ↓ GFR
stage 5:

Question 2

Normal BUN

Answer 2

7-18

high = kidney fxn less than normal
pts can get funny taste in their mouth

Question 3

How does diminished clearance affect creatinine and urea?

Answer 3

excretion rates for both remains constant at the expense of elevated plasma and waste products. (1 mg/min)

Question 4

What happens to osmolality (water handling)of pts with CKD?

Answer 4

2 scenarios

1. fraction of water Reabsorption ↓, meaning (dilute urine)
   - can get water deficient (hypernatremia)
2. their ability to excrete water is compromised and pt may develop hypoosmolality (concentrated urine)
   - can get water excess (hyponatremia)

(same water handling as normal kidneys, but you just cant concentrate and dilute as well as normal)

Question 5

What happens to Na+ levels in pts with CKD?

Answer 5

Same as normal kidney, but unable to adapt as well to changes
Na+ reabsorption ↓
Na+ secretion ↑

(believed that natriuretic peptide is present in CKD)

Question 6

Hallmark of CKD

Answer 6

loss in flexibility to respond to changes in external balance of Na+ and water

Question 7

What happens if you have CKD, and you suddenly intake lots of Na+?

Answer 7

you get edema
(volume expansion)

Body is used to secreting high Na+ already → cant do much more so rapidly → Na+ builds up extracellularly → water follows → edema

(more common than hypovolemia)

Question 8

What happens if you have CKD, and you suddenly decrease lots of Na+ intake (nausea, vomiting, diarrhea)?

Answer 8

volume depletion
(kidney cant conserve Na+ as well and adapt quickly)

Body is used to secreting high Na+ already → become Na+ depleted

(less common than hypervolemia)

Question 9

what happens to H+ when you have CKD?

Answer 9

Your nephron normally produces more NH4+ → keep acid balance normal
(you cant prod as much NH3 in CKD, can only prod 4x)

then as GFR gets really fucked up

Question 10

How does overproduction of certain hormones lead to uremic states?

Answer 10

overproduction of:

• ↑ PTH: due to hypocalcemia
• ↑natriuretic hormone due to volume overload

(just know that when urea is up, a whole bunch of other bad things are up)

Question 11

How does underproduction of certain hormones lead to uremic states?

Answer 11

Underproduction of:

• erythropoietin → anemia
• Vit D → secondary hyperparathyroidism

(just know that when urea is up, a whole bunch of other bad things are up)

Question 12

Anemia will occur if GFR

Answer 12

1. Erythropoiesis ↓

2. RBC lifespan shortens (uremic toxins)

Question 13

HTN occurs in almost 90% of pts with CKD, why?

Answer 13

1. Expansion of ECF (reduced ability to excrete INGESTED Na+ - remember secretion is already high, cant tell it to do more so fast)
2. increase RAAS
3. Autonomic NS dysfunction
   - baroreceptors are insensitive with increased sympathetic tone

Question 14

Mineral Bone disease of CKD

Answer 14

normal rxn to when Kidney fails → ↑ PO4- retension → ↓ Ca2+ → ↑ PTH →↑ PO4 excretion → ↑ Ca2+ to normal→ downregulates PTH

Over time, renal tubules are no longer responsive so you get ↑ ↑ ↑ PTH, which causes bone diseases since it reabsorbs so much Ca2+ from bone

Question 15

What does Vit D do?

Answer 15

• stim absorption of Ca2+ and Phosphorous from diet
• downregulates PTH

(its telling PTH, I got this, you sit out)

Question 16

What would a lack of Vit D result in?

Answer 16

decreased calcium absorption from diet,

thus, stimulating PTH

Question 17

What stimulates FGF-23? What does FGF-23 do?

Answer 17

1. FGF-23 is stimulated by increase in Phosphorous, PO4 (which again decreases ca2+)
2. It decreases kidney production of Vit D
   (which also decreases ca2+)

(what did we say happened with lack of Vit D?)

• watch this especially in CKD w/ GFR

Question 18

most common cause of CKD?

most important factor in decreasing progression of kidney disease?

Answer 18

Diabetic nephropathy

BP control