Kidney Stones

Question 1

Cystine stones

causes?

diagnostic test? 2

treatment 1

common in what population?

Answer 1

Cystine

hexagonal crystals

forms under low pH

causes

• cystinuria - genetic defect in a.a transporter in renal tubule + gastric mucosa

Dx

• Na nitroprusside test (+)
• 24 hr urine

Trmt

• alkalinization

common in CHILDREN

Question 2

What stones are these?

At what pH do they form?

Answer 2

Cystine

hexagonal crystals

forms under low pH

Question 3

What stones are these?

At what pH do they form?

Answer 3

Uric Acid

rosettes or rhomboid

forms under low pH

Question 4

uric acid stones

causes? 2

trmt? 3

Answer 4

Uric Acid

rosettes or rhomboid

forms under low pH

Examples

• Hyperuricemia (e.g. gout, Lesch-Nyhan Syndrome, psoriasis, obesity, purine gluttony)
• (+) cell turnover (tumor lysis syndrome)

Trmt

• alkalinization of urine (K citrate)
• allopurinol + febuxostat
• fluids, lots

Question 5

What stones are these?

At what pH do they form?

Answer 5

Calcium (Oxalate or Phosphate)

Dumbbell, Envelope, Needle-shaped

Oxalate: low pH

Phosphate: high pH

Question 6

Ca Oxlate stones

causes? 4

Trmt? 3

(note that these can be CaOx or CaPO4 stones)

Answer 6

Causes:

• Hypercalcemia - idiopathic, high PTH/PTHrP, Ca supplements, high Acid-Ash protein diet
• Ethylene glycol (oxalate)
• Crohns (oxalate) malabsorption of fats binds Ca in gut, leaving oxalate to be absorbed in high quanitities
• Vitamine C abuse (oxalate)

Trmt

• thiazides
• K citrate
• Ma/Mg (for Crohn’s - Mg complexes with oxalate to form a soluble compound)

Question 7

What stones are these?

At what pH do they form?

Examples?

Answer 7

Magnesium Ammonium Phosphate (Struvite)

“Coffin lid”

forms under high pH

Question 8

Struvite stones

Causes? 1

Trmt? 2

What is a common sequelae?

Answer 8

Magnesium Ammonium Phosphate (Struvite)

“Coffin lid”

forms under high pH

Examples:

• infection by urease (+) bugs: Proteus, Klebsiella, Staphylococcus (all hydrolyze ammonia -> alkaline urine)

Trmt

• treat infection w. antibiotics, urease inhibitors
• lithotripsy

Sequelae: staghorn calculi in renal pelvis (can cause obstruction + progressive renal insufficiency); COMMON

Question 9

definition of nephrocalcinosis?

Answer 9

calcification within renal parenchyma

Question 10

definition of nephrolithiaisis?

Answer 10

calcification in the upper urinary tract/collecting system; common in developed countries

Question 11

Supersaturation <1 results in? >1?

What happens to SS as urine volume increases?

Answer 11

<1 = dissolution

>1 = preciptiation

increase urine volume = decrease SS