II. Epidemiology

  1. Represents 10% of Kidney stones

III. Evaluation

IV. Types

  1. Pure Uric Acid Calculi
  2. Mixed calcium and Uric Acid Calculi

V. Causes

  1. Primary cause
    1. Acidic urine (pH <5.5)
  2. Other causes
    1. Gouty Arthritis (confers 2 fold risk of calculi)
    2. Excessive dietary purine intake (meats)
    3. End Ileostomy
    4. Insulin Resistance
      1. Results in impaired ammonia and citrate excretion
      2. Results in lower pH and increased urinary ammonia
      3. Increased Uric Acid crystallization

VI. Labs

  1. AM spot urine for Urine pH and Crystaluria
    1. Uric Acid stones form in acidic urine

VII. Imaging

  1. Non-contrast Abdominal CT
  2. XRay Abdomen
    1. Pure Uric Acid Calculi are radiolucent
    2. May be visualized if mixed calcium and Uric Acid

VIII. Management: Prevention of Uric Acid stone recurrence

  1. General
    1. Restrict dietary intake of Sodium and protein
    2. Maintain Urine output: over 2.5 liters per day
  2. Alkalinize urine (especially if Urine pH is low, acidic)
    1. Maintain Urine pH >5.5 (6.5 - 7.0 preferred)
    2. Potassium Citrate 10-20 mEq orally three times daily with meals
    3. Calcium Citrate 500 mg, two tablets daily with meals
  3. Hyperuricosuria (>800 mg/day)
    1. Potassium citrate as above
    2. Allopurinol 100-300 mg/day
    3. Purine (protein) restriction
    4. Reduce Urine Uric Acid excretion

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Ontology: Uric acid concentration in urine above normal (C0948643)

Concepts Finding (T033)
SnomedCT 282761000009106, 283001000009101
Italian Iperuricosuria
Japanese 高尿酸尿症, コウニョウサンニョウショウ
Czech Hyperurikosurie
Hungarian hyperuricosuria
English Uric acid level in urine elevated, Elevated urine uric acid, Uric acid concentration in urine above normal, Hyperuricosuria, Uric acid concentration in urine above normal (finding)
Portuguese Hiperuricosúria
Spanish Hiperuricuria
Dutch hyperuricosurie
French Hyperuricosurie
German Hyperuricosuria