Kidney Stones

Question 1

what are the risks associated with kidney stones?

Answer 1

• Diet – chocolate, tea, rhubarb, strawberries, nuts, spinach
• Season – vit D levels mediate calcium and oxalate levels
• Work – dehydration

Question 2

what medications are risk factors towards kidney stones?

Answer 2

diuretics, antacids, acetazolamide, corticosteroids, theophylline, aspirin, allopurinol, vit c and d, indinavir

Question 3

what are the predisposing factors for kidney stones?

Answer 3

• Recurrent UTIs
• Metabolic abnormalities
• Urinary tract abnormalities – pelviureteric junction obstruction, hydronephrosis, calyceal diverticulum, horseshoe kidney, ureterocoele, vesicoureteral reflux, ureteral stricture, medullary sponge kidney
• Family history

Question 4

what are the metabolic abnormalities associated with kidney stones?

Answer 4

o Hypercalciuria/hypercalcaemia: hyperparathyroidism, neoplasia, sarcoidosis, hyperthyroidism, Addison’s, Cushing’s, lithium, vitamin D excess
o Hyperuricosuria/plasma urate – on its own or with gout
o Hyperoxaluria
o Cystinuria
o Renal tubular acidosis

Question 5

what are the urinary tract abnormalities associated with kidney stone development?

Answer 5

pelviureteric junction obstruction, hydronephrosis, calyceal diverticulum, horseshoe kidney, ureterocoele, vesicoureteral reflux, ureteral stricture, medullary sponge kidney

Question 6

where do kidney stones tend to get stuck?

Answer 6

uteropelvic junction, vesicoureteral junction (VUJ), ureter, ureteric orifice

Question 7

how do kidney stones form?

Answer 7

• Stones form solute that precipitates and crystallises when solvents become supersaturated
• Crystals act as nidus – a place where more solutes deposit, build-up = crystals

Question 8

what are the different kinds of kidney stones?

Answer 8

Calcium Phosphate
Calcium Oxalate
Uric Acid
Struvite (MagPhos)
Xanthine 
Cystine

Question 9

what are the causes of calcium phosphate stones?

Answer 9

Metabolic or idiopathic

Question 10

what are the causes of calcium oxalate stones?

Answer 10

Metabolic or idiopathic

Question 11

what are the causes of uric acid stones?

Answer 11

Hyperuricaemia

Question 12

what are the causes of struvite (magphos) stones?

Answer 12

UTI

Question 13

what are the causes of cystine stones?

Answer 13

Renal tubular defect

Question 14

what is the appearance of calcium phosphate stones?

Answer 14

Wedge, smooth dirty white colour

Question 15

what is the appearance of calcium oxalate stones?

Answer 15

Envelope, spiky

Dark brown

Question 16

what is the appearance of uric acid stones?

Answer 16

Diamond/rhomboid crystals, red/brown, small

Question 17

what is the appearance of struvite stones?

Answer 17

Coffin lid shaped, staghorn, large

Dirty white

Question 18

what is the appearance of xanthine stones?

Answer 18

Red Brown

Question 19

what is the appearance of cystine stones?

Answer 19

Hexagonal crystals

Yellow/pink colour, semi opaque

Question 20

what is the pH of calcium phosphate stones?

Answer 20

> 5.5

Question 21

what is the pH of calcium oxalate stones?

Answer 21

6

Question 22

what is the pH of uric acid stones?

Answer 22

5.5

Question 23

what is the pH of struvite stones?

Answer 23

> 7.2

Question 24

what is the pH of cystine stones?

Answer 24

6.5

Question 25

what is the pathophysiology of uric acid stones?

Answer 25

Uric acid loses proton = urate ion, binds to sodium = monosodium urate

Question 26

what is the pathophysiology of struvite stones?

Answer 26

Bacteria uses urease to split urea into carbon dioxide and ammonia. Ammonia makes urine more alkaline. Precipitation of Mg, Ammonia and PO4.

Question 27

what is the pathophysiology of xanthine stones?

Answer 27

Biproduct or purine break down

Question 28

what is the pathophysiology of cystine stones?

Answer 28

Amino acid sometimes leaks into urine + crystallises

Question 29

what are the clinical features of kidney stones?

Answer 29

``` asymptomatic renal colic UTI Pyelonephritis Haematuria Proteinuria Sterile Pyuria Anuria Sepsis ```

Question 30

what are the clinical features of renal colic?

Answer 30

acute loin pain (radiates from flank to groin) with nausea/vomiting, restlessness

Question 31

what are the symptoms of kidney stones in renal obstruction?

Answer 31

– loin between rib 12 and lateral edge of lumbar muscles – pain not colicky but worse on movement

Question 32

what are the clinical features of kidney stones causing obstruction of mid ureter?

Answer 32

mimic appendicitis, diverticulitis

Question 33

what are the clinical features of kidney stones causing obstruction of lower ureter?

Answer 33

symptoms of bladder irritability and pain in scrotum/penis

Question 34

what are the clinical features of kidney stones causing obstruction of bladder or urethra?

Answer 34

pelvic pain, dysuria, strangury

Question 35

how are kidney stones diagnosed?

Answer 35

* FBC, U&E, Ca, PO4, glucose, bicarbonate, urate * Urine dipstick +blood, pH * Imaging

Question 36

what is the imaging used in kidney stones?

Answer 36

o KUB X ray o Spiral non contrast CT o IVU – CT preferable o US or MRI if pregnant or poor kidney function

Question 37

what is the supportive management of kidney stones?

Answer 37

ANALEGISA - Diclofenac, Codeine/morphine Fluids Antibiotics – cefuroxime, gentamicin)

Question 38

what is the management of kidney stones <5mm?

Answer 38

conservative - pass spontaneously

Question 39

what is the management of kidney stones >5mm?

Answer 39

Medical expulsive therapy  Calcium Channel blockers – e.g. nifedipine  α-receptor blockers – e.g. tamsulosin

Question 40

what is the management of kidney stones >1cm?

Answer 40

o Extracorporeal shockwave lithotripsy (ESWL) o Ureteroscopy with basket o Percutaneous nephrolithotomy