Renal Stones Flashcards
Epidemiology of stone disease?
3M:1F
Peak incidence 30-50y
Risk of recurrence of renal stones at 1/5/lifetime?
10% recurrence at 1 year; 50% recurrence at 5 years; 60-80% lifetime risk.
Hereditary RFx for renal stones?
RTA, G6PD, cytinuria, xanthinuria, oxaluria.
Lifestyle RFx for renal stones?
minimal fluid intake; excess vitamin c, oxalate, purines, calcium, animal protein ++
Medications RFx for renal stones?
Loop diuretics (frusemide); acetzolamide, topiramate, zonisamide.
Medical conditions RFx for renal stones?
UTI (with urea-splitting organisms); myeloproliferative disorders, IBD, gout, DM, hypercalcaemia disorders, sarcoidosis, obesity (>30).
What causes pain in renal stones?
Urinary obstruction -> upstream distension -> pain.
- Flank pain from renal capsular distension (non-colicky)
- Severe waxing and waning pain radiating from flank to groin/testis/tip of penis due to stretching or collecting system or ureter (ureteral colic).
CFx of renal stones?
Storage and voiding LUTS; terminal haematuria; suprapubic pain.
- N/V
- Diaphoresis
- Tachycardia/tachypnoea
- +/- trigonal irritation (F, U)
GU Ddx of renal colic?
- Pyelonephritis
- Ureteral obstruction of other cause (UPJ obstruction, clot colic 2” to gross haematuria)
- Gynaec: ectopic pregnancy, ovarian cyst torsion/rupture, PID.
- Testicular torsion
Abdominal Ddx of renal colic?
- AAA
- Bowel ischaemia
- Pancreatitis
- Other acute abdomen
Neurological Ddx of renal colic?
-Radiculitis (L1): herpes zoster, nerve root compression.
What are the narrow points for upper tract stones?
- UPJ
- Pelvic brim
- Under Vas deferens/ broad ligament
- UVJ
Outline the features in pathogenesis of renal stones.
- Supersaturation of stone constituents
- Stasis, low flow and low volume (dehydration)
- Crystal formation and stone nidus
- Loss of inhibitory factors
Which factors inhibit stone formation?
- Citrate (forms soluble complex with calcium)
- Magnesium (forms soluble compound with oxalate)
- pyrophosphate
- Tamm-Horsfall glycoprotein
Indications for hospital admission in renal stones?
- Intractable pain / vomiting
- Fever
- Compromisesd renal fxn (single kidney, bilateral obstruction)
- Pregnancy
How should septic patients with stones be managed?
Urgent decompression via ureteric stent or percutaneous nephrostomy.
Delay definitive Rx until clearance of infection.
Ix in renal stones?
- FBE
- UEC
- Serum calcium and uric acid
- MSU
- Xray KUB
- CT KUB (or CT IVP)
Acute medical management of renal stones?
- Analgesis +/- antiemetic
- NSAIDs
- Medical explulsion therapy
- IV fluids (if vomiting)
Why are NSAIDs used in renal stones in acute medical management?
Pain
Help lower intra-ureteral pressure
What is medical expulsion therapy?
- alpha blockers (increase rate of spontaneous passage in distal ureteral stones)
- CCBs
Indications for interventional management of renal stones?
- Infection / sepsis
- Renal impairment
- Bilateral obstruction
- Solitary kidney
- Inability to control Sx
- Prolonged obstruction
- Spontaneous passage unlikely
Interventional options for management of renal stones?
- JJ stent and delayed management
- Ureteroscopy and lithotripsy
- Shock wave lithotripsy
- Percutaneous nephrostomy
What is first line treatment for ureteral stones >10mm?
Extracorporeal shock wave lithotripsy (ESWL)
Dietary modifications for prevention of renal stones?
- Increased fluid (>2L/day), K+ intake
- reduce animal protein, oxalate, Na+, sucrose, fructose intake
- avoid high dose vitamin C supplements
Medication alterations for prevention of renal stones?
- Thiazide diuretics for hypercalciuria
- Allopurinol for hyperuricosuria
- Potassium citrate for hypocitraturia, hypyeruricosuria
Features of calcium stones?
- Radioopaque on KUB
- Reducing dietary Ca2+ NOT an effective prevention method
Treatment of calcium stones
-Increase fluids >2L/d
Calcium stones: Cellulose phosphate, orthophosphate for absorptive causes
Calcium oxalate: thiazides, +/- potassium citrate +/- allopurinol.
Calcium struvite: ABx (must remove stone)
Aetiology of uric acid stones?
Uric acid precipitates in low volume, acidic urine with a high uric acid concentration.
Key features of uric acid stones on imaging?
- Radiolucent on KUB
- Radioopaque on CT
Treatment of uric acid stones?
- Increased fluid intake
- Akalinisation of urine to pH 6.5-7 (bicarb, potassium citrate)
- +/- allopurinol (if serum uric acid levels elevated)
Aetiology of struvite stones?
- Infection with urea splitting organisms (e.g. proteus, pseudomonas)
- Produces alkaline urinary pH and precipitation of struvite (magnesium ammonium phosphate)
Hx features to elicit in renal colic?
- Pain characteristics
- ?Previous episodes and outcomes
- Complicating factors: pregnancy, renal impairment
- FHx
What proportion of renal stones are radiopaque?
90%
Common cause of obstructive pylonephrosis?
Usually GNB (E.Coli)
Management of obstructive pyelonephrosis?
- IV Abx (G-ve and enterococcus coverage)
- Urgent decompression (nephrostomy, JJ stent)
- Supportive (fluids, monitoring, +/- ICU/HDU)
What does spontaneous passage of renal stone depend on?
- Max size in transverse plane
- Location
- PHx of stone passage
Explain physiology of medical expulsive therapy?
- Ureter wall contain a1 R that mediating SM contraction
- a-blockers relax ureteric wall
- stone pass inc by 30%
Medical expulsive therapy dose?
Tamsulosin 0.4mg OD x 2/52
Follow up of renal stones?
- Home with analgesia
- Stain urine
- F/u imaging (XKUB if visible on Xray)
