When the 24h urinary citrate excretion is less than 320mg, it is called low citrate urine. Since microorganisms can break down urinary citrate, the urine specimen to be measured should not be left for a long time to avoid low results. The role of hypocitraturia in the formation of calcium-containing kidney stones is gradually being recognized. The incidence of hypocitraturia in patients with urolithiasis ranges from 19% to 63%. A variety of etiologies can cause hypocitraturia, such as type I renal tubular acidosis, enterogenic hyperoxaluria, absorptive hypercalciuria and renal hypercalciuria, excessive animal protein intake, chronic diarrhea, and oral thiazide diuretics. Some studies reveal that kidney stones are formed in patients with primary hyperparathyroidism only when they have low citrate urine, while stones are not formed in those with normal urinary citrate excretion. 1. Distal renal tubular acidosis: This is one of the common causes of calculous urolithiasis. Zhang Deyuan et al. reported 9 cases of renal tubular acidosis, 8 cases were accompanied by low citrate urine. Increased intracellular H’ in renal tubular acidosis results in increased urinary pH, while increased urinary calcium and decreased urinary citrate are due to its increased reabsorption. Complete. Urinary citrate can be reduced to <100mg/d in patients with renal tubular acidosis. 2, chronic diarrhea causing secondary acidosis: In Crohn's disease, colitis, most of the gastric resection and ileal resection or bypass can cause chronic diarrhea, resulting in reduced absorption of citrate in the small intestine and a 33% decrease in filtered citrate, resulting in low citrate urine. 3, thiazide drugs cause hypokalemia: patients using thiazide drugs, their blood potassium, urinary calcium and urinary citrate will be reduced, resulting in hypokalemia and hypocitraturia. 4, urinary tract infection: urinary tract infection, bacteria can break down ammonia into ammonium and hydroxyl ions and alkalinize the urine and reduce the solubility of calcium phosphate. Long-term persistent infection can produce citrate lyase and reduce urinary citrate. 5, primary hyperparathyroidism: parathyroid hormone can contribute to increased citrate excretion. Hyperparathyroidism can increase PTH secretion, low citrate urine formation, and promote urinary stone formation. Those with normal urinary citrate excretion are less likely to form stones. 6, sodium ion metabolism disorder: normal people 1:3 serving sodium 250mmol/d. Urinary citrate can be reduced by about O.63mmol/d, long-term sodium ion load disorder can lead to the occurrence of low citrate urine. 7, the net absorption of gastrointestinal alkali is reduced: the net absorption of gastrointestinal alkali caused by various reasons can lead to low citrate urine and urinary stone formation. According to the formula designed by Oh: gastrointestinal alkali net absorption = (urinary sodium + urinary potassium + urinary calcium + urinary magnesium) a (urinary chloride + 1.8 x urinary phosphorus), can estimate the effect of acid or base loading effect of diet on citrate excretion. Normal 24h urinary citrate is positively correlated with net gastrointestinal alkaline absorption. 8, primary intestinal citrate malabsorption: Fegan et al. did a comparative test of citrate absorption in 7 patients with idiopathic low-citrate kidney stones and 7 normal individuals, both groups were given oral potassium citrate 40 mmol/d, and found that 96% in the normal group of intestinal fluid. 98% of citrate was absorbed within 3 h, while the citrate absorption in the stone group was good, but the excretion of citrate was lower than that absorbed in the gastrointestinal tract The reason for this is probably due to the presence of an altered gene for the sodium a citrate co-transport factor. 9. Excessive intake of animal protein: Because animal protein containing sulfur amino acids are oxidized in the body to produce sulfate, the resulting acid load leads to lower urinary citrate excretion. The decrease in urinary pH and the increase in urinary uric acid resulted in an increase in the concentration of undissociated uric acid, thus favoring the formation of uric acid crystals, but no change in calcium salt concentration or soldier inhibitory activity was found. With urinary routine Hypocitraturia is diagnosed when the 24h urinary citrate excretion is measured to be less than 320mg. Pay attention to the identification of various causes of hypocitraturia and take appropriate treatment!