Kidney Stones

Question 1

Calcium Oxalate

Answer 1

MOST COMMON

Radio - opaque

Envelope-shaped

Precipitate w/ hypo-citrate in urine

Causes - ethylene glycol/Vit C abuse (inc oxalate) malabsorption like Chron’s (calcium binds to unabsorbed fats leaving oxalate alone)

Tx - thiazides, citrate, low sodium diet

Question 2

Calcium Phosphate

Answer 2

Radio-opaque

Wedge-shaped prisms

Precipitate w/ basic urine

Tx - thiazides and low sodium diet

Question 3

Ammonium Magnesium Phosphate

Answer 3

Radio-opaque

Coffin lid shape

Precipitate w/ basic urine

Causes - urease pos infections that hydrolyze urea to ammonia leading to basic urine

AKA struvite

Often cause staghorn caluli

Tx - surgical removal and eradicate infection

Question 4

Uric Acid

Answer 4

Radio-lUcent

Rhomboid shaped

Precipitate w/ acidic urine

Causes - dehydration, arid climates, gout, inc lysis / cell turnover like leukemia

Tx - alkalize urine and allopurinol

Question 5

Cystine

Answer 5

KIDS

Radiolucent

Hexagon (cystine = six sides)

Precipitate w/ acidic urine

Causes - hereditary auto rec disorder of cysteine transported in proximal tubule (also problems w/ ornithine, lysine, arginine - COLA)

Often see staghorn calculi

Tx - low sodium diet, alkalize urine, chelate if refractory