Factors affecting the formation of urinary stones Many factors affect the formation of urinary stones. The presence of supersaturated salts in the urine that form stone crystals, insufficient urinary crystal-forming inhibiting substances and the presence of nuclear matrix are the main factors in stone formation. Epidemiological factors include age, gender, occupation, socioeconomic status, diet composition and structure, water intake, climate, metabolism and genetics. Upper urinary tract stones tend to occur between 20 and 50 years of age. They are more common in men than in women. The peak age of onset for men is 35 years. In women, there are two peaks, at age 30 and 55 years. The incidence of upper urinary tract stones decreased at the time of World War II and has increased considerably during the interval and in the last four decades, suggesting an association with changes in economic income and diet. It was demonstrated that the increase of animal protein and refined sugar in the diet and the decrease of fiber contributed to the formation of upper urinary tract stones. Drinking large amounts of water dilutes the urine and reduces the formation of crystals in the urine. Relatively high temperature environment and reduced activity are also influencing factors, but occupation and climate are not single determining factors. Urinary factors 1. Excessive discharge of stone forming substances: increased discharge of calcium, oxalic acid and uric acid in urine. Long-term bed rest, hyperparathyroidism (reabsorptive hypercalcemia), idiopathic hypercalcemia (absorptive hypercalcemia – increased intestinal absorption of calcium or renal hypercalcemia – reduced renal tubular reabsorption of calcium), other metabolic abnormalities and renal tubular acidosis, etc., all increase urinary calcium excretion. Gout, persistent acidity of urine, chronic diarrhea and thiazide diuretics all increase uric acid excretion, and increased endogenous synthesis of oxalic acid or increased intestinal absorption of oxalic acid can cause hyperoxaluria. 2. Decrease in uric acidity and increase in pH. 3. Decreased urine volume increases the concentration of salts and organic substances. 4. Decrease in the content of substances that inhibit crystal formation in urine, such as citrate, pyrophosphate, magnesium, acidic mucopolysaccharide, certain trace elements, etc. 3. Abnormal anatomical structure Such as urinary tract obstruction, resulting in the deposition of crystals or matrix at the site of poor drainage, urinary retention secondary to urinary tract infection, which is conducive to stone formation. Fourth, urinary tract infection Most calcium oxalate stones have unknown causes. Calcium phosphate and magnesium ammonium phosphate stones are associated with infection and obstruction. Uric acid stones are associated with gout, etc. Cystine stones are rare familial hereditary diseases caused by the excretion of large amounts of cystine in the urine.