1. Nephrolithiasis Flashcards
Differential Diagnosis of Hematuria
- Benign Prostatic Hypertrophy (very vascular) + Medications (anticoagulants)
- Nephrolithiasis
- Glomerulonephritis
- UTI
- Malignancy
- Polycystic Kidney Disease
Diagnostic Evaluation of Hematuria
- Urine Dipstick positive for blood
-
Microscopic Urinalysis
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If less than 3 RBCs/high power field, repeat urinalysis 3 times every 6 weeks
- Negative: No workup
- Positive: (step below)
- If 3+ RBCs/high power field, assess for vigorous exercise, UTI, menstruation, or a recent urologic procedure
-
Repeat urinalysis 6 weeks after resolution of contributing factor
- Negative: No workup
- Positive: Renal function testing to assess for dysmorphic RBCs, cellular casts, proteinuria
-
Repeat urinalysis 6 weeks after resolution of contributing factor
-
If less than 3 RBCs/high power field, repeat urinalysis 3 times every 6 weeks
-
Renal Function Testing
-
Negative: Assess for malignancy risk factors, renal insufficiency, radiation contraindications, media allergy contrasts
- Low malignancy risk with other risk factors: Magnetic Resonance Urogram, Renal US, Non-Contrast CT & Urology Referral
- High malignancy risk with no other risk factors: CT Urogram & Urology Referral
- Positive: Nephrology Referral!
-
Negative: Assess for malignancy risk factors, renal insufficiency, radiation contraindications, media allergy contrasts
-
Done by Referred Physician: Cystoscopy
-
Negative: annual urinalysis for 2 years
- Negative: Release from care
- Positive: Repeat Cystoscopy within 3-5 years
- Positive: Treatment
-
Negative: annual urinalysis for 2 years
Preferred Imaging Modality for Hematuria
CT Urogram with and without Contrast
- Need without contrast because stones show up white and contrast is white
URINARY STONE DISEASE
Epidemiology
Risk Factors
EPIDEMIOLOGY:
- 20-60 yo (peak in 40s-60s
- M>F
- Caucasians 2-3x more than African Americans
- Low Urine Output - most significant correlation
- Geography: Hotter Climate (mountains, desert, tropics)
- Season: Hotter Temperature
- Occupation: Sedentary
- Asymptomatic stones have 50% chance of becoming symptomatic within 5 years
- After developing first stone, 50% chance of developing another stone within 5 years
RISK FACTORS:
- Endocrine: Hyperparathyroidism, DM
- Cardiovascular: Hypertension
- Metabolic: Obesity
- Urologic: Recurrent UTI, Urinary Retention
- Dietary:
- INCREASED protein, oxalate, sodium, calcium
- DECREASED citrate
URINARY STONE DISEASE
Pathogenesis
- Genetics
- Parents or siblings
- Environment
- Hot climate
- Lifestyle
- Diet
- Exercise
- Decreased fluid intake
- PROMOTERS
- Dehydration
- Acidic urine pH (high protein, Vitamin C)
- Uric Acid (gout)
- Medication (Topramax for migraines)
–> SUPERSATURATED URINE
fyi- INHIBITORS
- Citrate (binds calcium so it doesn’t precipitate out)
- Hydration
- Urine pH (basic)
- Restriction in Animal Protein (1 mg/kg/day)
- Na restriction (pulls calcium out with it)
URINARY STONE DISEASE
Locations
- Calyx
- Pelvic
- Staghorn
- Ureteral
- Bladder
URINARY STONE DISEASE
Most Common to Least Common Stones
- Calcium Oxalate AND Calcium Phosphate
- Calcium Oxalate
- Calcium Phosphate
- Struvite
- Uric Acid
- Cysteine
CALCIUM STONES
Epidemiology
Etiology
Appearance
Management
EPIDEMIOLOGY:
Most common stone
ETIOLOGY:
- DEHYDRATION IS THE MOST COMMON CAUSE!
- Hypercalciuria is the most common metabolic cause
- Primary Hyperparathyroidism
- Thyrotoxicosis
- Cushing’s Syndrome
- Hyperoxaluria
- Dietary Hyperoxaluria perhaps by spinach (secretion of 40-60 mg/day)
- Malabsorptive disorders
- Hypocitraturia
- Starvation
- Exercise
- Metabolic Acidosis - pulls calcium phosphate out of bones and increases amount of calcium in urine
- Renal Tubular Acidosis Type 1
APPEARANCE:
Radio-opaque
MANAGEMENT:
- Increase hydration to 2-3 L a day to urinate out 2 L
STRUVITE STONES
Epidemiology
Etiology
Formation
Composition
Appearance
Management
EPIDEMIOLOGY:
Most common cause of staghorn stones
ETIOLOGY:
- Infection from Indwelling Urinary Catheter
- Urease-producing bacteria (Proteus, Klebsiella, Pseudomonas, Haemophilus)
- Neurogenic Bladder
FORMATION:
Basic pH
COMPOSITION:
- Magnesium Ammonium Phosphate
- Calcium Carbonate-Apatite
APPEARANCE:
Radio-opaque
MANAGEMENT:
- Complete removal of stones within 2 years
- Sterilization of urinary tract
URIC ACID STONES
Epidemiology
Etiology
Formation
Appearance
Management
EPIDEMIOLOGY:
Most common in men with gout
ETIOLOGY:
- Dehydration is the most common cause (inadequate fluid intake, diarrhea)
- Acidic Urine
- Uric Acid
FORMATION:
Acidic urine
APPEARANCE:
Radiolucent!
MANAGEMENT:
- Potassium Citrate can dissolve stones
- Increase urine pH and decrease uric acid excretion with a low purine diet
- Reduce alcohol, fish, meat
CYSTINE STONES
Etiology
Pathophysiology
Diagnosis
Management
ETIOLOGY:
- Autosomal Recessive trait
- Excessive excretion of cystine, ornithine, lysine, and arginine
PATHOPHYSIOLOGY:
Low solubility of cystine
DIAGNOSIS:
Urine-sodium nitroprusside test
MANAGEMENT:
- Low salt diet (<2000 mg daily)
- Hydration (>3 L daily)
STAGHORN CALCULUS
Management
Complication if left untreated
MANAGEMENT:
Percutaneous nephrostolithotomy within 2 years
COMPLICATION IF LEFT UNTREATED:
50% loss of kidney function
ACUTE STONE EVENT
Clinical Presentation
History
Physical Exam
CLINICAL PRESENTATION:
- Acute flank pain (renal colic) radiating to the groin
- If distal, lower abdominal/groin pain with LUTS (hesitancy, straining, weak stream, dribbling)
- Nausea/Vomiting
- Gross/Microscopic Hematuria
HISTORY:
- Onset, location, duration of pain
- Associated symptoms: Fever, Nausea, Vomiting, LUTS, Hematuria
- FH of stones
- PMH: leading you towards Calcium, Struvite, Uric Acid, or Cystine stones
- Medications: Furosemide, Vitamin C, Calcium/Vitamin D, Topramate
PHYSICAL EXAM:
- Low grade fever (<100. Higher think pyelonephritis)
- Elevated BP or HR associated with pain
- Flank or Abdominal Tenderness
- No peritoneal signs
ACUTE STONE EVENT
Laboratory Assessment
Imaging
LABORATORY ASSESSMENT:
- CBC with Differential - to look for anemia due to blood loss or mild leukocytosiss
- Cr to rule out inappropriate contrast studies and determine need for relief of obstruction
- Electrolytes to identify RTA (hypercalciuria) or bilateral obstruction (hyperkalemia)
- Urinalysis to assess for microscopic hematuria
IMAGING STUDIES:
- Non contrast CT - gold standard, IDs all stones, location, and size
- Renal US - IDs obstruction and hydronephrosis, safe in pregnancy, but can miss small stones
- KUB - good for radioopaque stones but cannot ID obstruction
- IV Pyelogram or Urogram - not used often due to substantial radiation exposure
ACUTE STONE EVENT
Medical Management
Admission Criteria
Surgical Management
MEDICAL MANAGEMENT:
- Check renal function (Cr) before prescribing NSAIDs
- Relieve pain with NSAIDs (highly effective, better than opioids)
- Maintenance fluids sufficient in most cases
- Decide between No Intervention and Intervention
NO INTERVENTION = NSAIDs + TAMSULOSIN + RETURN IN 4-6 WEEKS
- Likely to pass (UVJ>Distal>Mid>Proximal, <5 mm
- Minimal-mild obstruction
- No associated infection
- Pain controlled
–> Medical Expulsive Therapy
- Alpha blockers (Tamsulosin) promote spontaneous passage of ureteral stones by smooth muscle relaxation and coordination
- Calcium Channel Blockers an option theoretically
INTERVENTION
- Unlikely to pass
- High grade obstruction
- Infection
- Unremitting pain
ADMISSION CRITERIA:
- Pain unrelieved by narcotics
- Fever/Infection
- Persistent nausea/vomiting
- Solitary Kidney
- Severe Obstruction/AKI
SURGICAL MANAGEMENT:
- Obstruction with infection mandates FAST DRAINAGE
- Ureteral Stent
- Nephrosotomy Tube
- Extracorporeal Shockwave Lithotripsy
- stones <2 cm, ideally 1 cm
- Great for renal and proximal ureteral stones
- Percutaneous Nephrostolithotomy
- stones >2 cm
- Stagorn calculi
-
LAST RESEORT:
- Ureteroscopy
- Laparoscopy
