Urolithiasis Flashcards
What is urolithiasis
Kidney stones
further classified as nephro, uretero, or cystolithiasis
What are the different types of stones
Calcium oxalate (MC) Calcium phosphate Uric acid MAP (struvite) Cystine Matrix Ammonium acid urate protease inhibitor stone
What do different stones look like on imaging
Calcium oxalate- Opaque Calcium phosphate Uric acid- Lucent MAP (struvite)- Opaque Cystine Matrix- Lucent Ammonium acid urate- Lucent protease inhibitor stone- Lucent
What is a calcium oxalate stone
Radio opaque (WHITE) that is resistant to dissolution caused by DEHYDRATION!
What is a uric acid stone
Forms in acidic urine (<6) and dissolves in alkalinized urine
What is a MAP (struvite) stone
Magnesium, ammonium, phosphate
Forms in alkaline urine, dissolves with acidification of urine
Caused by UTI’s
Forms Staghorn calculi
What is a cystine stone
MCC by genetic defect, Autosomal recessive (so homozygous are stone formers)
Caused by cystinuria
Dissolves in alkaline environment
What is a matrix stone
Proteus UTI associated
it is gelatinous so shock wave lithotripsy is not a good Tx
What is an ammonium acid urate stone
Associated with laxative abuse (and UTI’s)
Talk to your patient about healthier ways to have bowel movements
What is a protease inhibitor stone
Usually 2/2 precipitated drug (ex. Indinavir- HIV drug)
Not visible on stone protocol CT
What are some causes of Urolithiasis
Anatomic (not draining- obstruction/stasis)
Urine charac. (pH, specific gravity, crystal inhibitors)
Volume status (depletion, low UO, supersat urine)
diet
metabolic (high Ca, oxalate, uric acid- low Citrate)
disease states
UTI (proteus- low citrate- low ureteral peristalsis)
Meds (Indinavir)
What are crystal inhibitors
Citrate (complexes with calcium)
Urea (increases solubility of uric acid)
What are some disease states that cause urolithiasis
Obesity Metabolic acidosis (high urine Ca/phos, low citrate) RTA Sarcoidosis (hypercalcuria) Chronic diarrhea (volume depletion, acidosis) Cystinuria IBD (high oxalate) Hyperparathyroid (hypercalcemia) Medullary sponge kidney Adult PKD
What are urea splitting organisms
Proteus (matrix stone) Klebsiella Pseudomonas Serratia Staph
What happens when urea is split
Breaks down into ammonia and Bicarb (alkaline) = Struvite stone
What meds can cause UTI
Indinavir (protease inhibitor)
Vitamin C (inc. oxalate) and D (increase Ca absorption)
Triamterene
Furosemide (increase Ca excretion)
Acetazolamide (causes RTA stone)
Uricosuric agents (salicylates, probenecid)
What are common Sx of urolithiasis
flank pain
colic (waxing and waning)
radiation (to scrotum or vulva)
N/V, hematuria
What will labs show for urolithiasis
hematuria
BMP: high Creatinine, BUN
CBC: high WBC
UA: specific gravity, pH, Hgb
What will PE for urolithiasis show
fever
hyperkinetic (constantly walking around)
CVA ttp
What imaging can you get to evaluate Urolithiasis
KUB
US abdomen
CT stone protocol (A&P non con)
CT urogram (A&P w/ con)
What are indications for acute intervention
complete/high grade obstruction b/l obstruction obstruction w/ infection, in solitary kidney, or w/ rising Cr NPO 2/2 N/V Severe pain uncontrolled by analgesics
How do you treat acute urolithiasis
ABX for infection
Obstruction relief: ureteral stent, nephrostomy tube
Later proceed to definitive stone management
-goal is to prevent sepsis and renal damage
How can you treat a lower tract stone (bladder, urethra)
Cystourethroscopy
Extracorporeal shock wave lithotripsy
open stone removal
dissolution
How do you treat upper tract stones (kidney, ureter)
trial of passage (5mm or less) dissolution ESWL ureteroscopy w/ stone manipulaiton percutaneous nephrolithotomy open or laparoscopic surgery
Candidates for trial of passage are based on
Renal function pain control PO intake No infection stone size (5mm or less)
What do you give during a trial of passage
Fluids po analgesics po Alpha blockers (Tamsulosin) Filter urine periodic imaging to assess hydronephrosis
What is dissolution for uric acid stones
chemolysis using Sodium bicarb or Potassium citrate to make urine more ALKALINE (>6.5)
Can take up to 3 months to work
-Then irrigate the system via nephrostomy tube, sodium bicarb, and THAM
What is dissolution for cystine stones
chemolysis usine Potassium citrate to make urine more ALKALINE (>7.5)
Irrigate the system with sodium bicarb, THAM, and NAC
What is dissolution for Struvite and Calcium phosphate stones
Irrigate with ACIDIC solution (Renacidin)
What is ESWL
IF <2mm, using a gel barrier between skin and laser, skock wave generator delivered for 60-90 min (manipulate table so lasers hit as cross hairs)
Gate w/ ECG to avoid inducing arrhythmia
Do with fluoroscopic imaging (real time XR)- may need to stent and inject dye if radiolucent
Must be sedated or under anesthesia
Decreased renal perfusion for up to 3 weeks
What are ups and downs to ESWL
Outpatient, non-invasive, and sedated
But, stone fragments cant be removed
What are CI to ESWL
CI: pregnancy, coagulopathy, UTI, aneurysm, AAA
relative CI: Cystine or Matrix stone, chronic pancreatitis, distal obstruction
What are complications of ESWL
Renal or retroperitoneal hematoma Ecchymosis UTI sepsis Ureteral stricture Pain
What is Ureteroscopy with stone manipulation (upper Tx)
In OR (gen anesthesia) use transurethral approach to place flexible scope and deliver energy to calculus
can use laser, ultrasonic, or electrohydraulic lithotripsy, or pneumatic impactor (jack hammer)
Stone is broke up and fragments basketed out
+/- ureteral stent temp.
What are complications of Ureteroscopy with stone manipulation
ureteral avulsion/ perforation submucosal tunneling ureteral stricture stone goes outside of ureteral lumen UTI bleeding pain
What is Percutaneous nephrolithotomy (upper Tx)
In IR or OR, needle placed into flank under fluoroscopic guidance, and advanced into renal collecting system (kidney)
Energy delivered to lithotripsy stone
Fragments grabbed and removed
Good for stones >2mm (STAGHORN)
CI to PCNL include
UTI
Coagulopathy
No percutaneous renal access
What are complications of PCNL
bleeding
sepsis
renal pelvis perforation
PTX, hydrothorax
What is indication for open or laparoscopic surgery
Fail trial of passage, dissolution, ESWL, ureteroscopy with stone manipulation, and PCNL
What are the ways urolithiasis surgery can be preformed
Cystolithotomy (large stone or concurrent surgery)
Pyelolithotomy
Ureterolithotomy
Anatrophic nephrolithotomy (Brodel’s avascular plane)
Metabolic evaluation includes
H&P, UA, stone analysis, serum labs, 24 hr urine collection
Who is at high risk for recurrent stones/ stone complications
Peds stone formers solitary kidney Staghorn Cystine, uric acid, Struvite stone formers Nephrocalcinosis gout chronic UTI FH stones Crohn's (GI dz) Osteoporosis (bone dz) Profession where stone can endanger others (pilot)
How can you prevent future stones
Fluid intake (UO 2500 ml/d) Increase fluids with citrate (NO POP) Low sodium (<2300mg) Low animal protein intake Low oxalate (beets, strawberry, rhubarb, chocolate, spinach, liver, tea, peanuts, potatoes) Moderate Calcium intake (800-1000 mh/d) Avoid high dose vitamin C (causes increased oxalate)
What is PRAL (stone prevention)
Porential Renal Acid Load
high PRAL= low Citrate
so keep PRAL low by limiting animal protein, cheese and egg yolks, and increasing fruits and veggies
What meds can help prevent future stones
Potassium citrate (alkalinize urine) thiazide allopurinol Pyridoxine, B6 Cholestyramine Thiols
How does Potassium citrate work
Citrate binds calcium and stops crystallization
corrects acidosis= increase urinary citrate= decrease urinary calcium
Caution in: uncontrolled DM, renal insuff, delayed gastric emptying, K sparing diuretic
ADE of potassium citrate include
hyperkalemia
peptic ulcers
How do thiazides work
Increase reabsorption of Ca into kidneys= decreased urine calcium excretion= corrects acidosis
*Can worsen stone dz if it causes hypokalemia- give with K+
ADE of thiazides are
Weakness, fatigue
How does Allopurinol work
Decreases uric acid levels therefor decreasing stone incidence IF patient was hyperuricosuric
How does pyridoxine work
Helps metabolize oxalate
Take to prevent B6 deficiency and prevent hyperoxaluria
How does cholestyramine work
Bind bile acid and make colon wall less permeable= less oxalate gets into system
(bile acids normally increase permeability)
How do thiols work
Treat and prevent cystinuria by increasing solubility
*Tiopronin, D-Penicillamine
