Nephrolithiasis

Question 1

What percentage of men and what percentage of women will have a kidney stone by age 70?

Answer 1

12% of men

5% of women

Question 2

80% of stones are made of what?

Answer 2

calcium

Question 3

Of the calcium stones, are there more calcium oxalate or more calcium phosphate stones?

Answer 3

more oxalate

Question 4

What are the three less common kinds of stones?

Answer 4

uric acid
struvite
cystine

Question 5

What is the most helpful imaging study for KS? Others?

Answer 5

CT scan is the most common, but we use US for repeaters and KUB can be helpful on occasion

Question 6

KUB are only really good for what kind of stone?

Answer 6

calcium stones - they’re the only ones that would be radiopque on xray (cystine maybe, but less likely)

Question 7

How do you treat a kidney stone acutely?

Answer 7

pain meds, hydration, alpha blocker or ca channel blocker

Question 8

What are the different means you can use to get a stone out?

Answer 8

ureteroscopy
extracorporeal shock wave lithotropsy
endoscopic lithotripsy
pyelolithotomy
percutaneous nephrolithotomy

Question 9

What will calcium oxalate crystals look like?

Answer 9

both dumbbell-shaped and envelope-shaped

some also have a needle-shaped appearance

Question 10

What are the risk factors for calcium stone formation?

Answer 10

1. increased calcium excretion
2. increased uric acid excretion
3. reduced citrate excretion
4. low urine volume
5. increased oxalate excretion

Question 11

What are three things that can cause idiopathic hypercalciuria contributing to kidney stone formation?

Answer 11

1. absorptive hypercalciuria (autosomal dominant elevated active vitamin D levels)
2. Fasting (resorptive) hypercalciuria - bone loss
3. Renal hypercalciuria - renal leak with abnormal calcium reabsorption in the proximal tubule

Question 12

What are some things that can cause low citrate contributing to Ca kidney stones?

Answer 12

1. chornic diarrhea
2. renal tubular acidosis
3. ureteral diversion
4. high protein diet
5. topiramate

Basically anything that gives metabolic acidosis!!!

Question 13

What are some ways you can get hyperoxaluria contributing to Ca kidney stones?

Answer 13

1. high oxalate diet
2. increased oxalate absorption from a low calcium diet , absorptive hypercalciuria, enteric hyperoxaluria
3. overproduction of oxalate (primary hyperoxaluri

Question 14

What are some medical conditions associated with caclium stone formation>

Answer 14

primary hyperparathyroidism - too much Ca resorption from bone

medullary sponge kidney (reflux of urine back into the renal papilla of the kidney)

distal renal tubular acidosis

Question 15

What should you do in a metabolic workup of a calcium stone?

Answer 15

1. measure plasma calcium
2. measure parathyroid hormone
3. measure electrolytes
4. check serum uric acid
5. 24 hr urine collection for volume, calcium, uric acid, citrate, osalate, creatinine, pH, sodium, and phosphorus

Question 16

What’s the dietary treatment for clacium stones?

Answer 16

increase fluid
decrease salt intake (NaCl is a drive of calcium excretioninto urine)
decrease protine (less acid in the urine, so you don’t get the acid-induced drop of citrate concentration)
maintain calcium!!!! counterintuitive, but you need Ca to bind to oxalate and limit oxalate absorption from the gut
limit oxalate

Question 17

What meds can you give to manage Ca kidney stones?

Answer 17

thiazide diuretics!!

potassium citrate or bicarbonate (alkalinize the urine to increase citrate excretion)

orthophosphate

Allopurinol/Febuxostat to reduce uric acid production

calcium carbonate to bind to oxalate and stop absorption

Question 18

Uric stones make up only 5-10% of the stones in the US. Where are they much much more common?

Answer 18

40% of stones in hot, arid climates due to low urine volumes and acidic urine pH

Question 19

Do uric stones precipitate at alkaline urine or acidic urine?

Answer 19

acidic urine

Question 20

How can you diagnose a uric stone?

Answer 20

analyze the stone material once recovered

indirectly by demonstratin increased urine uric acid excretion

Question 21

What’s the treatment for uric stones?

Answer 21

increase urine output with fluid intake

alkalinization of the urine

allopurinol/febuxostat

Question 22

What are struvite stones made of?

Answer 22

magnesium ammonium phosphate

Question 23

What do struvite stones look like?

Answer 23

coffin lids

Question 24

Struvite stones precipitate at alkaline urine or acidic urine?

Answer 24

alkaline - decreases the solubility of phosphate

Question 25

What causes the increased ammonium levels for the struvite stone formation?

Answer 25

infection with urease positive bacteria like klebsiella or proteus the ureas breaks down the urea to the ammonium

Question 26

How do you treat struvite stones?

Answer 26

antibiotics to kill the bacteria acetohexemic acid - a urease inhibitor so you don't get the ammonium formation even if the bacteria are there ESWL or percutaneous nephrolothotomy required because you can't pass a struvite stone

Question 27

What do cysteine stones look like?

Answer 27

hexagonal - practically pathognomonic for cystinuria

Question 28

Cystinuria is a genetic disorder passed along in what inheritance pattern?

Answer 28

autosomal recessive

Question 29

What's the disorder?

Answer 29

imparied cystine transport leading to decreased proximal tubular re-absorption and increased cystine excretion

Question 30

How are the cystinuria subtypes characterizes?

Answer 30

by how much cystine is excreted by the parents, who are usually asympaotmati cheteroxygotes: 1/1: only small amounts II/II: large amounts III/III; intermediate amounts combinations can occur

Question 31

What will cystein stones looke like on imagine compared to the calcium stones?

Answer 31

fuzzy gray in appearance - less radio-opaque than calcium

Question 32

How do you deal with cystine stones medically?

Answer 32

high fluid intake (over 3 L/d) alkalinization of urine restrict dietary Na (you want more proximal reabsorption of cysteine and it will follow Na) Penicillamine tiopronin, and and captopril will complex with cystine and make it more soluble for easy excretion

Question 33

Why are the cystine stones relatively resistant to ESWL? What can you do then?

Answer 33

They're softer than other stones you can do percutaneous nephrolithotomy ultrasonic lithotropsy renal transplant will cure disease actually

Question 34

If someone has a first stone, medical treatment is only indicated when what?

Answer 34

then there's evidence of active stone disease: formation of new stones, enlargement of old stones, passage of gravel, multiple stones at presentation

Question 35

What is the risk of a symptomatic 2nd stone in 1 year? 5 years? 10 years? Which gender?

Answer 35

15% at 1 year 35-40% in 5 years 50% at 10 years men more than women

Question 36

What are the complications of ESWL

Answer 36

ift he pieces only break down to a little less than 3 cm, you still have risk of obstruction (need stenting) reversibly damages blood vessels and tubules new hypertension rpesumably due to renin release from focal areas of renal ischemia measureable impairment in renal function presumably due to scar formation residual caliculi after ESWL have high incidence of stone formation