Kidney Stones

Question 1

Classification

Answer 1

• Kidney - nephrolithiasis
• ureter- ureterolithiasis
• bladder - cystolithiasis

By composition

• Calcium containing (80%)
  
  • calcium oxalate
  • calcium phosphate
• magensium ammonium phosphate
• urice acid
• cysteine
• mixed

Question 2

History

Answer 2

• renal colic/passage of stones/haematuria/infection
• family history
• diet

Question 3

examination

Answer 3

• flank tenderness/sites of infection/ urinalysis
• obesity/ hypertension/gouty tophi
• diabetes

Question 4

Clinical features

Answer 4

• renal colic - excruciating ureteric spasms “loin to groin”
• renal obstruction - felt in the loin, between rib 12 and later edge of lumbar muscles
• obstruction of mid-ureter - may mimic appendicitis
• obstruction of lower ureter - bladder irritability and pain in scrotum, penile tip or labia
• obstruciton in bladder or urethra - pelvic pain, dusuria, interrupted flow
• haematuria
• proteinuria
• sterile pyuria

Question 5

Investigations

Answer 5

• FBC
• U and Es
• Ca2+
• phosphate
• glucose
• bicarb
• Urine dipstick - +ve blood
• MSU - micrscopy and culture
• urine PH
• Imaging
  
  • spural non contrast CT
  • KUB XRay
  • IVU - radioopaque contrast injected and serial films taken intil constrast seen down to the level of obstruction

Question 6

Treatment

Answer 6

Initially

• analgesia
• IV fluids
• antibiotics

Stones <5mm in lower ureter - 90-95% pass spontaneously

Stones >5mm/pain not resolving - medical expulsive therapy: nifedipine or alpha blockers promote expuslion and reduce analgesia requirement most pass within 48 hours

If not passing, try extracorporeal shockwave lithotripsy (ESWL)

Question 7

Prevention

Answer 7

General:

• drink plenty
• normal dietary Ca2+ intake

Specifically

• calcium stones: thiazide diuretic is used to decrease calcium
• Oxalate - decreased oxalate intake - pyridoxine may be used
• struvite: treat infeciton promptly
• Urate- allopurinol
• cystine: vigorous hydration to keep urine output >3l/day