Given how frequently patients present with renal colic, it is helpful for FY1s to understand the basic management. Specifically this article will help ensure you do the relevant investigations (& know why you're doing them) & provide safety netting on discharge.

Types of stones:
  • Calcium oxalate - Most common
  • Magnesium ammonium phosphate - can be called Struvite stones
  • Uric acid
  • Cystine
Presentation:
Kidney stones typically present classically with renal colic, pain or discomfort in the flank area radiating around to the groin. Other common presentations may include difficulty passing urine, increased frequency, haematuria, testicular pain or even symptoms of dysuria or fevers if infection is also present.

How to diagnose?
History is key with all diagnosis. Renal colic is often described by patients as an aching pain in the flank with radiation to the groin that can come and go in waves. Patients will often tell you that it is the worse pain they have experienced, woman can say its worse than labour!

Investigations:
  • Urine dip - blood, protein, ?infection 
  • Renal function - AKI ?obstuctive nephropathy
  • Calcium, phosphate, PTH, urate 
  • CT KUB  - low-dose non-contrast CT  of renal tract can help identify location and size of a stone
  • Renal USS - Good for young patients, pregnant patients or children as no radiation involved, may not show the stone but can show hydronephrosis
Management:
  • Analgesia
  • NSAIDS are first line unless otherwise contraindicated -  Diclofenac is often first line
  • Plenty of fluids - IV or oral 
  • Small stones <5mm - will often pass spontaneously and can be managed conservatively. 
  • Large stone >5mm may require intervention- Discuss with Urology team - interventions listed below 
  • Shock wave lithotripsy - used to break larger stones into smaller pieces
  • Ureteroscopy for stone removal
  • Percutaneous nephrolithotomy for large stones or impacted “Staghorn stones” ( coagulation must be checked first)
Other considerations that may determine management other than stones size
  • Obstruction, 
  • Gross haematuria
  • Pain 
  • Infection
  • Loss of kidney function
  • Patient occupation e.g Pilots
Prevention:
  • Encourage patients to drinks lots of water
  • Avoid carbonated drinks
  • Reduce salt
  • Thiazide diuretics can reduce the amount of calcium excreted in the urine and reduce the recurrence of calcium oxalate stones 
References:
https://www.nice.org.uk/guidance/ng118/chapter/Recommendations#diagnostic-imaging
https://www.uptodate.com/contents/diagnosis-and-acute-management-of-suspected-nephrolithiasis-in-adults

Dr Emma-James Garden FY3