Hypocitraturia

Introduction Low citrate definition, when measured 24h urinary acid excretion is less than 320mg, it is called hypodecanoic acid. Because the microorganism can decompose uric acid, the urine sample to be tested cannot be placed for a long time, so as not to make the measurement result low. The role of hypocapnia in the formation of calcium-containing kidney stones is gradually recognized. The incidence of hypocapnia in patients with urolithiasis is 19% to 63%. A variety of causes can cause hypoaciduria, such as type I renal tubular acidosis, intestinal high oxalic aciduria, absorptive hypercalciuria and renal hypercalciuria, excessive animal protein intake, chronic diarrhea, oral thiophene Azide diuretic and the like. Some studies have revealed that patients with primary hyperparathyroidism develop kidney stones only in low-acid urine, while those with normal urinary acid excretion do not form stones.

Cause

A variety of causes can cause hypoaciduria, such as type I renal tubular acidosis, intestinal high oxalic aciduria, absorptive hypercalciuria and renal hypercalciuria, excessive animal protein intake, chronic diarrhea, oral thiophene Azide diuretic and the like. Some studies have revealed that patients with primary hyperparathyroidism develop kidney stones only in low-acid urine, while those with normal urinary acid excretion do not form stones.

1. Distal renal tubular acidosis: This is one of the common causes of calcium urolithiasis. Zhang Deyuan et al reported 9 cases of renal tubular acidosis, and 8 cases were associated with hypodecic aciduria. Increased H' in the cells of renal tubular acidosis leads to an increase in urinary pH, and an increase in urinary calcium and a decrease in urinary citrate due to increased reabsorption. Completeness. Urinary acid can be reduced to <100mg/d in patients with renal tubular acidosis.

2. Chronic diarrhea caused by secondary acidosis: Chronic diarrhea can be caused in Crohn's disease, colitis, most of the stomach resection and ileal resection or shunt, so that the absorption of citrate in the small intestine is reduced, filtered sputum The acid salt decreased by 33%, resulting in low acid uric acid.

3. Thiazide drugs cause hypokalemia: patients with thiazide drugs, blood potassium, urinary calcium and urinary acid will be reduced, resulting in low potassium blood and low acid uric acid.

4. Urinary tract infection: When the urinary tract infection occurs, the bacteria can decompose ammonia into ammonium and hydroxyl ions and alkalinize the urine to reduce the solubility of calcium phosphate. Prolonged persistent infection can produce citrate lyase and reduce uric acid.

5. Primary hyperparathyroidism: Parathyroid hormone can promote the increase of citrate excretion. Hyperparathyroidism increases PTH secretion, lowers sputum formation, and promotes urinary calculi. It is not easy to form stones when the urinary acid is discharged normally.

6. Sodium ion metabolism disorder: normal people 1:3 serving sodium 250mmol / d. Urinary niacin can be reduced by about O.63mmol / d, long-term sodium ion load disorder can cause hypocapnia.

7. Reduced net absorption of gastrointestinal alkali: a decrease in the net absorption of gastrointestinal alkali caused by various causes can lead to the formation of urinary stones due to hypohydric aciduria. According to Oh's calculation formula: net absorption of gastrointestinal alkali = (urine sodium + urinary potassium + urinary calcium + urinary magnesium) - (urine chlorine + 1.8 × urinary phosphorus), can be estimated by the acid or alkali load on the diet The effect of acid salt excretion. Normal 24h urinary acid salt was positively correlated with net absorption of intestinal base.

8. Primary intestinal citrate malabsorption: Fegan et al. performed a comparison of citrate absorption in 7 patients with idiopathic hypocapnia kidney stones and 7 normal subjects. Both groups were given oral potassium citrate. 40mmol / d, found in the normal group of intestinal fluid 96%. 98% of citric acid was absorbed within 3 hours, while the citrate absorption of the stone group was good, but the citrate excretion was lower than that of the gastrointestinal tract. The reason may be due to the presence of sodium citrate. The helper transport factor gene has changed.

an examination

Related inspection

Urine routine kidney CT examination

Urine routine, when measured 24h urinary acid excretion less than 320mg can be diagnosed as hypodecanoic acid.

1. Clinical and other imaging data found or suspected kidney mass.

2. Inflammatory lesions in the kidney area, renal tuberculosis, hydronephrosis.

3. Kidney damage.

4. Allergic to iodine, contraindications to patients with angiography.

5. Guide the interventional diagnosis and treatment measures such as needle biopsy and attraction in the kidney area.

Differential diagnosis

Pay attention to identify low-acid uric acid caused by various reasons, such as:

1. Distal renal tubular acidosis.

2. Chronic diarrhea causes secondary acidosis.

3. Thiazide drugs cause hypokalemia.

4. Urinary tract infection.

5. Primary hyperparathyroidism.

6. Sodium ion metabolism disorder.

7. Net absorption of intestinal base is reduced.

8. Primary intestinal citrate malabsorption.

9. Excessive intake of animal protein.

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