1 - Urinary Stone Disease Flashcards
Urinary stone disease factoids
3rd MC urinary tract d/o
Male > female 2.5:1
Age 30-50’s
Urolithiasis?
Stone formation anywhere in urinary tract
Nephroloithiasis
Stones in the kidneys
Ureterolithiasis
Stones in the ureters
Urinary calculi
Polycrystalline aggregates of crystalloid and organic matrix
Stone formation is a result of?
Uninary supersaturation of solute
- low fluid intake -> low urine volume -> high concentrations of stone forming solutes in urine
Most stones are?
Calcium (85%)
- radiopaque
Factors that affect urinary stone formation
- high protein intake
- high salt intake
- inadequate hydration
- Sedentary lifestyle
Stones of our fathers?
A clint eastwood movie
- wait, maybe not
They are genetic though
- calcium based - 50% heritable
- cystinuria - (autosomal dominant d/o) leads to cysteine stones
Urine pH effects on stones?
Acidic
- uric acid stones
- cystine stones
Alkaline
- UTI (urease producing organisms)
- > struvite stones
5 types of urinary stones?
- Calcium oxalate
- Calcium phosphate
- Struvite (mg, ammonium phosphate)
- Cystine
- Uric acid
Staghorn stones are
Struvite
- magnesium ammonium phosphate
MC type of stone?
Calcium oxalate (by far MC)
Risk factors for calcium oxalate stones?
Urinary pH 5.5-6.8
High sodium High protein Dehydration Hypercalciuria Low urine citrate
Oxalate stones result from?
Digestion: oxalate is metabolic end product
Excess ascorbic acid (>2g/day)
- H urinary oxalate levels
Strongest promoter of oxalate stone formation?
Urinary oxalate
- it has a high affinity for calcium so calcium follows it into the urine
How does citrate promote calcium phosphate and oxalate stones?
Urinary citrate binds w calcium making it unavailable to bind with phosphate and oxalate
PH effect on citrate?
Acidosis -> L urinary citrate
Alkalosis -> H urinary citrate
Risk for calcium phosphate stones?
- alkaline urine
- high sodium
- high protein
- dehydration
- hyepercalciuria
- low urine citrate
(Pretty similary to calcium oxalate)
MC struvite stone presentation?
Women w recurrent UTI w urease-producing baceria
- proteus
- pseudomonoas
- providencia
- klebsiella
- staph
- mycoplama
High urine pH (>7.2)
Struvite stones are made of?
Magnesium-ammonium-phosphate stones
Struvite stones on radiograph?
Radiopaque
Staghorn calculi?
Upper Urinary tract stones that involve:
- renal pelvis (extend to 2+ calyces)
- composed of struvite
Cystine stones pH?
Acidic urine (<5.5)
Cystine in urine?
The only amino-acid that is insoluble in urine
Risk factors for uric acid stones?
- hyperuricemia
- myeloproliferative d/o
- malignancy w H uric acid production
- abrupt and dramatic wt loss
Uric acid urine pH?
Acidic <5.5
Uric acid stones radiograph?
Radiolucent
Clinical findings for stones?
Obstruction
Obstruction - cholic pain
Hematuria
Describe the obstructing stones presentation
- sudden onset (awaken from sleep)
- severe, unremitting flank pain
- n/v
- constant movement of pt
Where is the pain with stones?
Initial Episodic
- can radiate anterior over abd
As progresses down ureter
- refers to ipsilateral groin
May have CVA tenderness
If the stone gets lodged at ureterovesicular junction?
Marked urinary urgency and freq
Males get pain at tip of penis
Stone size and pain?
Doesnt correlate w symptoms severity
Ddx for stones?
Bleeding in kidney Pyelonephritis GYN AAA Mesenteric ischemia Herpes zoster Drug-seeking
More info on each on slide 25
labs for stones?
UA
- hematuria
- urine pH
Serum studies - chem 17
Stone analysis - urine strainer
Gold standard of imaging for stones?
Non-contrast CT
- will show all stones radiopaque or radiolucent
Other imaging for stones
Plain film (KUB)
- gets most stones
- cannot r/o stones
Renal US
- preggo
- er use
Acute tx for stones?
Asymptomatic and no infection
- nothing
= 5-6 mm pass spontaneously
Hydration is key to stone passing
Meds
- analgesics
- antiemetic
- alpha-blocker
Indications for referral w stones?
Indicated for: – Infection – Obstruction – Intractable pain (admit & control pain) – Persistent nausea/vomiting – Stone size ≥6 mm – Fails to pass w/in 4 weeks – Anatomic abnormalities or single kidney – Patient is pregnant – Patient is immunocompromised – PMH of severe renal disease
A pt with obstructive urinary calculi w fever and infected urine?
Emergent urologic eval and drainage
“Pus under pressure”
What is extracorporeal shock wave lithotripsy (ESWL)?
TOC - in 75% requiring tx
- works well in renal pelvis
- upper 2/3 of ureter
- size >1.5cm
When using ESWL you need to make sure the pt?
D/c NSAIDS x 3 days prior to lower bleeding risk
What may be required following ESWL to facilitate passage of fragmented stones?
Ureteral stent
Stones in lower 1/3 of ureter may need?
Ureteroscopic stone extraction
Who needs percutaneous nephrolithotomy?
- Stone in renal collecting system
- upper 2/3 of ureter
- size >2 cm may need?
Open stone surgery is reserved for?
Pt w
- complex anatomy
- obstruction
- large infected struvite stones
(<5% of cases that need intervention)
Bottom line for acute stone tx?
Push fluids Pain control Confirm stone Admit (if tx/pain failure) Refer (large, infection, comorbids)
Recurrent stone formers need?
Lab workup
- 24hr urine
- serum PTH
- Uric acid -> r/o primary hyperparathyroidism or gout
With recurrent stone formers you should not restrict?
Calcium - low calcium diets lead to higher risk of stones
- complex process, explained on 43
Fiber effect in stones?
Fiber -> H fecal extraction of calcium -> lower urinary calcium
Why do soda’s effect stones?
High in phosphate -> H calcium phosphate stones
Dont take more than ___ vitamin c if you want to avoid stones?
> 2g/day
Foods high in oxalate?
Grits and ovaltine
Much much more on slide 45
Recurrent stone formers w high/low urinary calcium need? (Med)
High - Thiazide diuretics
- HCTZ
- chlorthalidone
Low - potassium citrate therapy
- raise citrate in calcium stone formers
- raise pH in uric acid/cystine stone formers
Prevent stones w
Water
1.5-2L/day
Follow up for chronic stone formers?
24hr urine q 6 mo
Repeate stone analysis if interventions are failing
Yearly CT
Iguana tap it
But i have reptile dysfunction
