Renal stones

Question 1

85% of renal stones are what composition?

Answer 1

calcium oxalate

Question 2

Calcium oxalate stones

1) hyper____ is a major risk factor
2) radio- LUCENT/ OPAQUE

Answer 2

1) calciuria

2) opaque

Question 3

Renal stones associated with an inherited disorder?

Answer 3

Cystine

disorder of transmembrane cystine transport > decreased absorption of cystine from intestine and renal tubule

Question 4

Uric acid stones

1) uric acid is a product of ___ metabolism
2) may precipitate when urinary pH is ____
3) radio_____

Answer 4

1) purine
2) low
3) lucent

Question 5

renal stones caused by diseases with extensive tissue breakdown e.g. malignancy

Answer 5

uric acid stones

Question 6

Calcium phosphate stones

1) may occur in renal __ __
2) renal tubular acidosis types __ and __ increase risk of stone formation
3) radio______

Answer 6

1) tubular acidosis (high urinary pH increases supersaturation of urine with calcium and phosphate)
2) 1 and 3 (not 2 and 4)
3) opaque (similar composition to bone)

Question 7

staghorn calculi?

Answer 7

struvite

Question 8

Struvite stones

1) formed from …..
2) occur as a result of ____ producing bacteria (and are thus associated with chronic ____) > produces alkaline conditions > crystals precipitate
3) slightly radio____

Answer 8

1) magnesium, ammonium and phosphate
2) urease, infections
3) opaque

Question 9

state the urine acidity associated with the following stones

1) calcium phosphate
2) uric acid
3) struvate
4) cystine

Answer 9

1) normal- alkaline
2) acid
3) alkaline
4) normal

Question 10

Radio-opaque or radiolucent?

1) calcium oxalate
2) mixed calcium oxalate/ phosphate
3) triple phosphate
4) calcium phosphate
5) urate
6) cystine
7) xanthine

Answer 10

1) O
2) O
3) O
4) O
5) L
6) semi-O
7) L

Question 11

Stag-horn calculi

1) Involve the renal ___ and extend into at least 2 calyces.
2) They develop in ACIDIC/ ALKALINE urine and are composed of ______
3) which pathogen predisposes to their formation

Answer 11

1) pelvis
2) alkaline, struvite (ammonium magnesium phosphate)
3) proteus and ureaplasma urealyticum

Question 12

radiographic appearance: semi-opaque, ‘ground glass’ appearance

Answer 12

cystine

Question 13

risk factors for renal stones?

Answer 13

dehydration
hypercalciuria, hyperparathyroidism, hypercalcaemia
cystinuria
high dietary oxalate
renal tubular acidosis
medullary sponge kidney, PKD
beryllium or cadmium exposure

Question 14

risk factors for urate stones?

Answer 14

gout

ileostomy (loss of bicarbonate and fluid > acidic urine)

Question 15

drugs that promote calcium stones?

Answer 15

loop diuretics
steroids
acetazolamide
theophylline

Question 16

what drug class can prevent calcium stones?

Answer 16

thiazides (increase distal tubular calcium resorption)

Question 17

pain relief for renal colic?

Answer 17

IM diclofenac

Question 18

initial investigations for renal stones?

Answer 18

urinalysis
CRP/
creatinine

Question 19

Best investigation for renal stones?

Answer 19

non-contrast CT-KUB

sensitivity 97%, specificity 95%

Question 20

when can renal stones be managed expectantly?

Answer 20

<5mm (will typically pass within 4 weeks of symptom onset)

Question 21

Management

1) stone burden <2cm in aggregate
2) stone burden <2cm in pregnant females
3) complex renal calculi and staghorn calculi

Answer 21

1) Shockwave lithotripsy
2) Ureteroscopy
3) Percutaneous nephrolithotomy

Question 22

prevention of calcium stones?

Answer 22

hydration
low animal protein and low salt diet
thiazide diuretics

Question 23

prevention of oxalate stones?

Answer 23

cholestyramine and

pyridoxine reduce urinary oxalate secretion

Question 24

prevention of uric acid stones?

Answer 24

allopurinol

urinary alkalisation e.g. oral bicarbonate

Question 25

Management of renal stone <5mm causing ureteric obstruction and infection

Answer 25

surgical emergency > decompression with e.g. nephrostomy, ureteric catheter or stent

Question 26

risks associated with Shockwave lithotripsy?

Answer 26

shock waves can cause solid organ injury fragmentation of larger stones may result in ureteric obstruction NB: analgesia required during and after

Question 27

Shockwave lithotripsy vs Percutaneous nephrolithotomy?

Answer 27

Shockwave lithotripsy: shock wave generated external to the patient, internally cavitation bubbles and mechanical stress lead to stone fragmentation. Percutaneous nephrolithotomy: access gained to the renal collecting system then intra corporeal lithotripsy or stone fragmentation is performed and stone fragments removed.