Nephrolithiasis

Question 1

Gold standard Dx of kidney stones?

Answer 1

Non-contrast CT.

Question 2

What is the utility of U/S and KUB in kidney stone dx?

Answer 2

1) U/S detects hydro, but not good for distal stones or early hydro. Can be used in pregnancy.
2) KUB - not sensitive enough, but can be used to track resolution.

Question 3

What lab test is ordered for kidney stones?

Answer 3

U/A micro. Should show RBCs - if not, probably not a stone.

Question 4

What are the four kinds of kidney stones?

Answer 4

Calcium (80%), Struvite (15%), uric acid (5%), cysteine (1%).

Question 5

At what pH do calcium stones precipitate at?

Answer 5

Calcium phosphate: high pH.

Calcium Oxalate: low pH.

Question 6

X ray findings of calcium stones?

Answer 6

Radioopaque

Question 7

Shape of calcium stones?

Answer 7

envelope or dumbbell-shaped (calcium oxalate).

Question 8

What can cause calcium oxalate stones?

Answer 8

ethylene gycol (antifreeze), vitamin C abuse, hypocitraturia, malabsorption (eg crohns, short bowel).

Question 9

Most common lab findings in pt presenting with calcium oxalate stone?

Answer 9

Hypercalciuria, normocalcemia.

Question 10

Treatment of calcium oxalate stones?

Answer 10

Hydradation, thiazides, citrate.

Question 11

What are struvite stones?

Answer 11

Ammonium magnesium phosphate

Question 12

At what pH do struvite stones precipitate?

Answer 12

high pH.

Question 13

X ray findings of struvite stones?

Answer 13

radioopaque

Question 14

Shape of struvite stones?

Answer 14

staghorn caliculi, coffin lids.

Question 15

Common causes of struvite stones?

Answer 15

Infection w/ urease + bugs such as proteus mirabilis, staph saphrophyticus, klebsiella.

Question 16

What does urease + bugs have to do with struvite stones?

Answer 16

Convert urea to ammonia, alkanizing the urine and making conditions for precipitation.

Question 17

Treatment of struvite stones?

Answer 17

Treat udnerlying infection + surgical removal of stone.

Question 18

At what pH do uric acid stones precipitate?

Answer 18

low pH.

Question 19

X ray findings of uric acid stones?

Answer 19

radiolucent. Must use CT or ultrasound instead.

Question 20

Shape of uric acid stones?

Answer 20

rhomboid or rosettes.

Question 21

Risk factors for uric acid stones?

Answer 21

Hyperuricemia (gout), High cell turnover conditions like leukemia and tumor lysis syndrome.

Question 22

Treatment of uric acid stones?

Answer 22

Alkalinization of urine (potassium bicarb)
Inhibition of uric acid formation (allopurinol)
Make excess uric acid into soluble metabolite (rasburicase).

Question 23

At what pH do cysteine stones precipitate?

Answer 23

low pH.

Question 24

X ray findings of cysteine stones?

Answer 24

radiolucent.

Question 25

Shape of cysteine stones?

Answer 25

hexagonal or staghorn caliculi.

Question 26

Etiology of cysteine stones?

Answer 26

Hereditary (AR) condition - cysteine channels in PCT lose function; cystinuria. Cysteine poorly soluble, stones form.

Question 27

In what age group are cysteine stones most commonly seen?

Answer 27

children

Question 28

What is the test for cysteine stones?

Answer 28

Sodium cyanide nitroprusside.

Question 29

Treatment of cysteine stones?

Answer 29

alkalinization of urine.

Question 30

What are the easy guidelines for management of a kidney stone?

Answer 30

3cm - Surgery.

Question 31

What other meds can be used as medical expulsive therapy?

Answer 31

CCBs (amlodipine)

Alpha blockers like terazosyn/doxyzosyn.

Question 32

If the stone is proximal, what will be surgical approach be?

Answer 32

Laparoscopic > > > open

Question 33

If the stone is distal, what will the surgical approach be?

Answer 33

percutaneous ureteroscopy + anterograde removal.

Question 34

If the patient is septic, what will the approach be?

Answer 34

Nephrostomy (proximal), stent (distal).