Urolithiasis Flashcards
Define Nephrolithiasis
Stones in the kidney, ureter, or bladder of the urinary tract
1st Phenomena of Pathophysiology of Stones
Supersaturation of urine by stone-forming constituents
Crystals or FB can act as a nidus
2nd Phenomena of Pathophysiology of Stones
More likely responsible for calcium oxalate stones
Deposit of stone material on a a renal papillary calcium phosphate nidus
Calcium phosphate precipitates the basement membrane & erodes interstitium & accumulate in sub epithelial space
Subendothial deposits erode through the papillary urothilium
Stone matrix, calcium phosphate, & calcium oxalate deposit on nidus to create stone
Etiology of Nephrolithiasis
Low fluid intake with low volume of urine production
Hypercalcuria
Reasons for Hypercalcuria
Increase in intestinal absorption of calcium
Excess reabsorption of calcium from bone
Inability of renal tubules to properly reclaim calcium in glomerular filtrate
Types of Stones
Calcium Uric acid Cystine Struvite Xanthine
Risk Factors of Nephrolithiasis
Family history
Gout
Primary hyperparathyroidism
Age for Highest Risk of Nephrolithiasis
Most: 20-49 years old
Peak: 35-45 years old
Clinical Presentation of Nephrolithiasis
Pain Infection Hematuria Acute onset severe flank pain radiating into the groin Gross/microscopic hematuria N/V Fever/chills
Workup of Nephrolithiasis
UA: hematuria, bacteria or leukocytes
CBC: elevated WBCs
CMP: electrolytes, BUN/Cr levels, parathyroid hormone level with ionized calcium level
24 hour urine: identify urinary risk factors
Imaging: KUB, renal US, CT without contrast
Most Common Findings on 24 Hour Urine
Hypercalcuria
Hyperoxaluria (oxalate)
Hyperuricosuria (uric acid)
Hypocitraturia (citrate)
What does the 24 hour urine evaluate?
Volume pH Calcium Sodium Phosphate Citrate Uric acid Cystine Oxalate Magnesium
KUB & Nephrolithiasis
Good for: monitoring stones, large stones, radiopaque stones
Less radiation
Inexpensive
Renal Ultrasound & Nephrolithiasis
Good for diagnosing hydronephrosis
Difficult to see ureteral stones
No radiation
Test of choice for pregnancy
CT & Nephrolithiasis
Gold standard for stones
Treatment of Nephrolithiasis Depends on
Stone size Infection with obstructing stone Solitary kidney Pregnancy Patient preference Surgery Medication Diet
Stone Size & Treatment of Nephrolithiasis
8mm 0-10% passage on own
Infection with Obstructing Stone & Treatment of Nephrolithiasis
CONSULT UROLOGIST
Needs ureteral stent placement
Worry about sepsis
Solitary Kidney & Treatment of Nephrolithiasis
CONSULT UROLOGIST
Stent placement same day
Stone removal
Pregnancy & Treatment of Nephrolithiasis
Stent placement
Pain medication
Patient Preference & Treatment of Nephrolithiasis
Try to pass on won
Alpha-blocker (Flomax, Doxazosin)
NSAIDs & pain medication
Surgical Treatment of Nephrolithiasis
Stent placement vs. percutaneous nephrostomy
Extracorporeal Shockwave Lithotripsy (ESWL)
Uteroscopoy
Percutaneous Nephrostolithotomy (PNL)
Open nephrostomy
Medication Treatment of Nephrolithiasis
Flomax IM/IV Ketorolac Hydrocodone or oxycodone IM/IV metoclopramide Morphine NSAIDs
Diet in Treatment of Nephrolithiasis
Increase fluids
Avoid excess salt & protein intake
Moderation in food high in oxalate
Do NOT limit calcium
Foods High in Oxilate
Green leafy vegetables
Chocolates
Tea
Calcium Oxalate Stones
Most common stone
Formation caused by high calcium & high oxalate excretion
Uric Acid Stones
Most common radiolucent stone
Low urine volume and acidic urine pH promote precipitation of uric acid
Describe Calcium Oxalate Crystals
Diamond looking
Describe Uric Acid Crystals
Flattened hexagonal appearing
Cystine Stones
Genetic cause of kidney stones
White pearly looking stones
Describe Cystine Crystals
Hexagonal shaped
Struvite Stones
Grow rapidly over weeks or months
Grow into stag horn calculus
Caused by UTI: urease-producing organism
Urease-Producing Organisms
Proteus
Klebsiella
Xanthine Stones
Rare
Caused by inborn defect of xanthine oxidase
Xanthine cannot be oxidized to uric acid
Hypercalciuria
Common cause is idiopathic
Thiazide therapy can lower calcium excretion
Decrease sodium intake
Hyperoxaluria
Intestinal hyper-absorption
Increase consumption
Hyperuricosuria
Elevated urinary excretion of uric acid
Promotes calcium oxalate stone formation
Medications for Hyperuricosuria
Allopurinol: reduce calcium stones
Potassium citrate: raise pH, dissolves stones
Outpatient Refer to Urology
Stone >5 mm
Failure to pass symptomatic stone after conservative management
Treatment of Outpatient Nephrolithiasis
Stent placement Extracorporeal shock wave lithotripsy (ESWL) Ureteroscopic lithotripsy Percutaneous nephrolithotomy Laparoscopic stone removal
Urgent Inpatient Referral to Urology
Urosepsis Intractable pain Bilateral obstructing stones Acute renal failure Anuria
Define Bladder Stones
Hard buildups of minerals that forming the urinary bladder
Most Common Bladder Stone
Uric acid stones
Surface of Bladder stones
Smooth & faceted
Jagged & spiculated
Risk Factors of Bladder Stones
Bladder diverticulum Bladder outlet obstruction (most common) Neurogenic bladder UTIs Catheters
Presentation of Bladder Stones
Abdominal pain/pressure Hematuria or dark colored urine Difficulty urinating Urgency/frequency Interruption of stream Penile discomfort UTI
Physical Exam for Bladder Stones
Rectal exam: large prostate
Bladder or pelvic x-ray
Cystoscopy
UA with culture
Treatment of Bladder Stones
Cystoscopy in office for small stones
Surgery: cystolithalopaxy, cystolithotomy, TURP, simple prostatectomy
Medical: potassium citrate (Urocit K)
Cystolithalopaxy
Uses laser to break them up and pull it out through the scope
Cystolithotomy
Don’t break up the stones
Make an incision & remove the stones