Urinary Stones Flashcards
Types of urinary stones
● “Calculi” – literature and Urologists
● Nephrolithiasis – Stone in the kidney
● Ureterolithiasis – Stone in the ureter
● Bladder stones – Stones in the bladder
Urinary Stones epidemiology
● 55% w/ familial Hx of stones
● About 50% recurrence in 4 years
● 3rd most common urinary tract disorder
● 8.8% of the US population (and rising, especially in peds)
○ 10.6% of men; 7.1% of women
● Initial presentation between 30 to 50 years of age
Calculus Formation: 3 Stage Process
● Stage 1 – Nucleation
○ Homogeneous
○ Heterogenous
● Stage 2 – Growth: The nidus travels to the renal papilla and grows
● Stage 3 – Aggregation: Crystals start to aggregate
Retained in the kidney until dislodged…
if they ever dislodge (staghorn stones)
Nucleation - 2 types
○ Homogenous – Ions precipitate out of solution due to
concentration, temperature change, etc.
○ Heterogenous – Clumping of cells (blood cells,
epithelial, debris from infection) becomes a nidus to
catalyze stone formation
Causes/Risk Factors of Urinaroy Stones
● Supersaturation – concentrated urine
● Absences of Inhibitors
○ Citrate – binds calcium and inhibits crystal formation
● Metabolic Disturbances: Hyperparathyroidism, metabolic syndrome, renal tubular acidosis, GI disease or disorders, DM, cystinuria
● Nutritional and Environmental Factors
○ Low urine output*
○ High oxalate diet *
● Drugs that crystalize the urine: Triamterene
Uric Acid stone etiology
○ Increased urine acidity (pH < 5.5)
■ Increased Vit C (ascorbic acid)
○ Uric acid crystals can be the entire
stone, but more commonly are the
nidus for calcium or mixed Ca++/uric
acid crystals
Calcium Oxalate stone etiology
○ Serum Ca++ normal, Urinary Ca++ is high
○ Hypocitraturia – not consuming enough
○ Hyperoxaluria – consuming too much
■ Excess absorption – bacterial
overgrowth, pancreatic or biliary Dz,
bariatric surgery (ileojejunal)
Calculus Types
● Calcium Oxalate – 70-80%
● Calcium Phosphate - 10%
● Uric Acid - 10%
● Cystine - <2%
● Struvite - Chronic UTI (Staghorn stones)
Phases of Renal Colic
● Phase 1 – Acute or Onset phase
○ Insidious, intermittent, cyclic exacerbations of pain that peaks
in 30 min–6 hours
○ If sleeping, Pt will awake with abrupt onset of pain
● Phase 2 – Constant
○ Sustained maximal pain intensity with spastic cyclic waves,
lasting 1–4 hours (Pts in the ER)
● Phase 3 – Relief
○ Gradual diminishment, lasting 1–3 hours
Presentation of urinary stones
○ Asymptomatic until calculi causes urinary obstruction
● Renal Colic: Follows dermatomes T10 to S4
■ Flank pain – UPJ stone
■ Hip/low abdominal pain –
Ureteral stone
■ Groin or suprapubic pain – UVJ
● Nausea and vomiting
● Hematuria
● Persistent need to urinate
● Dysuria
● Scrotal, labial, penile, or pelvic pain
When a patient comes in presenting with potential urinary stones ask about:
● Pattern of pain
○ Ebbs and flow
○ Positional pain vs intractable pain
○ CVA to flank, to abdomen, to groin
● Nausea and vomiting
● Hematuria
● UTI Sx (fevers)
● Medications
Past Medical History clues for urinary stones
● Past Hx of kidney stone
● Gout
● Gastric bypass
● Hyperparathyroidism
● Diabetes/metabolic syndrome
Differential Diagnosis to think of for urinary stones
Digestive System
● Pancreatitis
● Bowel obstruction
● Peritonitis
● Hernia
Musculoskeletal
● Low back pain
● Hernia
GU Tract
● UTI
● Pyelonephritis
● Acquired UPJ obstruction
● Interstitial cystitis
● Urethritis
Diagnosis of Urinary stones
Will not diagnose a stone, but may help solidify a suspicion
● Hematuria
● Acidic urine
● Alkaline (struvite stones)
Urine Microscopy
● Pyuria (leukocytes in urine)
● Crystals under microscope
Blood Tests
● Serum creatinine, uric acid, calcium
● Imaging
Imaging for urinary stones
● Non-Contrast CT
● X-ray - KUB
● Ultrasound - Pregnancy
● MRI
Diagnostic test of choice for urinary stones
Non-Contrast CT Scan
● Scan of the abdomen and pelvis
● Sees all types of stones
● Can see stones < 1 mm in size
