• Clinical presentation: severe flank pain that radiates to the groin or genitalia. Pain is more likely to be colicky than constant and unremitting. Bloody urine or microscopic hematuria are characteristic. Fever suggests superimposed infection
• Stones < 5mm pass on their own
• Stone types: Calcium oxalate, struvite, uric acid, cystine
• Pathogenesis: stones need 3 conditions for formation:
• (1) nidus
• (2) right solubility environment (concentration and pH)
• (3) absence of inhibitors

Calcium Stones – Most common 80%

• Composition: Calcium oxalate or calcium phosphate
• Epidemiology: Men, 20-30 years old
• Recurrence: multiple (every 2-3 years), 50% will get recurrence at 5 years
• Genetics: Familial predisposition
• X-ray: radiopaque – will show up white for you non-ray guys
• Etiology: In general, any condition associated with an elevated Serum Calcium predisposes you to Calcium stones
• Hyperparathyroidism: Ý PTH Þ Ý Ca resorption Þ Ý serum Ca
• Disorders which lead to Ý production of Vitamin D
• Thyrotoxicosis: Ý bone turnover
• Idiopathic: associated with Ý urinary calcium excretion
• Associated conditions:
• Renal tubular acidosis
• Medullary sponge kidney
• Hyperuricosuria
• Disorders of oxalate metabolism
• Treatment: Correct underlying abnormality
• Furosimide diuretic(Ý urinary Ca excretion)
• Oral citrate (inhibitor of stone formation)

Struvite – Infection Stones – 12%

• Composition: Magnesium ammonia phosphate - will precipitate at Ý pH (pKa 7.5
• Epidemiology: women
• Risk Factors:
• Catheters : serves as nidus around which stone can form
• Urinary tract infections (Proteus, Klebsiella – urease bugs) Þ produce alkaline urine
• Pathogenesis: bacterial urease Þ degrades ammonium to ammonia Þ Ý pH of urine Þ stones precipitate at this pH
• Pathology: "Staghorn" calculi – looks like a 3 pronged trident
• X-ray: radiopaque
• Treatment:
• Surgical removal
• acidifying urine
• anitbiotic suppression (can be difficult since antibiotics can’t penetrate stone and serve as an unremitting source of bacteria)

Uric Acid – 7%

• Composition: uric acid – will precipitate at ß pH (pKa 5)
• Epidemiology: Men
• Risk factors:
• Gout (50%)
• Chemotherapy for leukemia lymphoma:
• Tumor Lysis Syndrome: Cell lysis associated with chemo Þ hypouricemia Þ acute uric acid load Þ ß pH Þ stone formation
• Ileostomy
• Calcium oxalate stones: serve as a nidus
• hyperoxaluria
• X-ray: Radiolucent
• Treatment: Allopurinol; urinary alkalinization

Cystine – Congenital cystinuria – 1%