## Epidemiology of Renal Stones in India **Key Point:** Calcium oxalate stones account for approximately 70–80% of all renal and ureteric stones in India, making them the most common type encountered in clinical practice. ### Composition and Prevalence | Stone Type | Prevalence (%) | Composition | Associated Factors | |---|---|---|---| | Calcium oxalate | 70–80 | CaC₂O₄ (monohydrate or dihydrate) | High dietary oxalate, hypercalciuria, dehydration | | Uric acid | 10–15 | Uric acid crystals | Low urine pH, gout, high purine diet | | Struvite (triple phosphate) | 5–10 | MgNH₄PO₄·6H₂O | Urinary tract infections, alkaline urine | | Calcium phosphate | 3–5 | Ca₃(PO₄)₂ | Alkaline urine, renal tubular acidosis | ### Risk Factors for Calcium Oxalate Stone Formation 1. **Dietary factors:** High oxalate intake (spinach, nuts, chocolate), excessive vitamin C supplementation 2. **Metabolic:** Hypercalciuria, hyperoxaluria, hyperuricosuria 3. **Environmental:** Dehydration, tropical/subtropical climate (common in India) 4. **Genetic:** Primary hyperoxaluria **High-Yield:** In the Indian subcontinent, the combination of hot climate, dietary habits (high oxalate foods), and dehydration makes calcium oxalate stone formation significantly more common than in Western populations. **Clinical Pearl:** Calcium oxalate stones are radiopaque and visible on plain radiographs (KUB), unlike uric acid stones which are radiolucent. ## Why Other Options Are Less Common - **Uric acid stones (10–15%):** More common in gout patients and those with persistently acidic urine; less prevalent in general population. - **Struvite stones (5–10%):** Associated with recurrent UTIs and are more common in women; not the most common overall. - **Calcium phosphate (3–5%):** Rare as a primary stone; usually forms as a component of mixed stones.
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