Source: OME
Types
Common types of kidney stones:
|
Type
|
Pt
|
Radio
|
Crystal shape
|
|
Calcium
(oxalate, phosphate)
>75% of stones
|
· ⤴️PTH
· High-sodium, high-oxalate diet
· Malabsorption (oxalate)
· Renal tubular acidosis (phosphate)
|
· Small
· Radiopaque
|
· Octahedron or envelope (oxalate)
· Wedge or rosette (phosphate)
|
|
MAP
(Struvite)
|
· Upper tract infection with urease-producing organisms (e.g., proteus)
|
· Large
· Radiopaque
|
· Rectangular/prism
|
|
Uric acid
5%-8% of stones
|
· Gout
· Diabetes/ metabolic syndrome
· Myeloproliferative disorders
|
· Small
· Radiolucent
|
· Yellow/brown
· Rhomboidal
|
|
Struvite (MAP) stones
|
|
|
RF
|
Rx upper UTI
Urease-producing 👾 (Klebsiella, Proteus)
|
|
Path
|
Hydrolysis of UREA → Ammonia:
Urea → NH3 + C02
NH3 + H2O → NH4 + OH-
⤴️ Urine pH
Precipitation of Magnesium Ammonium Phosphate salts
|
|
Clx
|
· Large staghorn calculi
· Fever, mild flank pain due to infection
· Obstruction of collecting system
· ATROPHY of renal parenchyma
|
|
Tx
|
Surgical Resection & Abx
|
|
Uric Acid kidney stones
|
|
|
RF
|
· ⤴️ Uric acid excretion: Gout, myeloproliferative disorders
· ⤴️ urine concentration: Hot, arid climates; dehydration
· ⤵️ urine pH: Chronic diarrhea (Gl bicarbonate loss), metabolic syndrome/DM
|
|
Path
|
· Acidic urine favors formation of uric acid (insoluble) over urate (soluble)
· Supersaturation of urine with uric acid precipitates crystal formation
|
|
Clx
|
· Radiolucent stones (not visible on x-ray)
· Uric acid crystals on urine microscopy
· Urine pH usually <5.5
|
|
Tx
|
Alkalinization of urine (potassium citrate)
|
Tx:
|
Prevention of rx stones
|
|
|
Dietary
|
• Increase fluids (produce >2L urine/day)
• Reduce sodium (<100 mEq/day)
• Reduce protein
• Normal calcium intake (1200 mg/day)
• Increase citrate (fruits & vegetables)
• Reduced-oxalate diet for oxalate stones (dark roughage, vitamin C)
|
|
Drugs
|
• Thiazide diuretic
• Urine alkalinization (potassium citrate/bicarbonate salt)
• Allopurinol (for hyperuricosuria-related stones)
|
Fast HY Review 