12-09-2011
Hyperuricosuric calcium nephrolithiasis is characterized by calcium oxalate or calcium phosphate stones in persons with hyperuricosuria. The hyperuricosuria is most commonly due to an excessively purine-rich diet; however, hyperuricosuria may be related to overproduction of uric acid in as many as 30% of these patients. This may represent a latent form of gout. In contrast to calcium-based stones, uric acid stones form in an acidic environment with a urinary pH that is always below 5.5. The solubility of uric acid depends on 3 factors: (1) urinary pH, (2) uric acid concentration, and (3) urinary volume. Based on these factors, the causes of uric acid stones can be categorized as follows:
Acidic urine
Gouty diathesis
Chronic diarrhea
Inflammatory bowel disease
Exercise/dehydration
Familial
Hyperuricosuria
Gouty diathesis
An excessively purine-rich diet
Inborn errors of metabolism
Hypoxanthine-guanine phosphoribosyl-transferase deficiency
Phosphoribosylpyrophosphate synthetase overactivity
Glucose-6-phosphatase synthetase deficiency
Myeloproliferative disorders
Leukemia
Hemolytic anemia
Neoplasia
Medications
Chemotherapy
Low urinary volume
GI disorders
Strenuous exercise/dehydration
