Medication Summary
Medical therapy depends on the type of stone produced. Children with idiopathic hypercalciuria caused by renal tubular calcium leak may benefit from treatment with a thiazide. If idiopathic hypercalcinuria is gastrointestinal (GI) absorptive and a low-calcium diet does not return urinary calcium levels to the reference range, neutral sodium phosphate may be beneficial in reducing dietary calcium absorption. Chelating agents such as cellulose sodium phosphate (Calcibind) are no longer available on the US market.
Hypocitraturia is treated with oral potassium citrate. Supplemental citrate leads to correction of hypocitraturia.
Struvite stones require treatment with an appropriate antibiotic. Surgical intervention or ESWL may be necessary if the stone produces high-grade obstruction, if antibiotic therapy is not adequately eliminating infection, or after infection is cleared to remove stone fragments.
Uric acid stones require alkalinization of urine with sodium bicarbonate or potassium citrate in 4 divided doses. Urine pH levels should be maintained at 7.5 or greater. Uric acid is much more soluble in alkaline than acid urine. Allopurinol is indicated in children with uric acid lithiasis whose daily uric acid excretion exceeds the reference range.
The medical management of cystinuria is mainly based on hyperhydration and urine alkalinization. Sulfhydryl agents such as tiopronin should be added.
Alkalinizing Agents
Class Summary
Alkalinizing agents are used to increase urinary pH and/or provide increased citrate in the urine in persons with hypocitruria. Both have a tendency to increase solubility of some minerals.
Sodium citrate/citric acid (Cytra-2, Liqui-DualCitra)
Sodium citrate and citric acid mixture is indicated for systemic metabolic acidosis (ie, renal tubular acidosis), urinary alkalinization, or hypocitraturia. It contains disodium citrate. It is administered orally and is metabolized to bicarbonate by the liver. The preparation contains 500 mg sodium citrate and 334 mg citric acid per 5 mL (ie, 1 mEq potassium and 1 mEq sodium per 1 mL).
Sodium citrate and potassium citrate mixture (Citra-3, Tricitrates)
Sodium citrate and potassium citrate mixture is indicated for treatment of systemic metabolic acidosis, urinary alkalinization, or hypocitraturia. It is administered orally and metabolized to bicarbonate in the liver. Each 5 mL of the preparation contains sodium citrate 500 mg, citric acid 334 mg, and potassium citrate 550 mg (each mL contains 1 mEq potassium, 1 mEq sodium, and 2 mEq bicarbonate).
Diuretics
Class Summary
These agents are used to decrease urinary calcium excretion.
Hydrochlorothiazide (Microzide, Oretic)
Hydrochlorothiazide, by an unknown mechanism, decreases urinary calcium excretion. By lowering urinary calcium concentration, the risk of calcium forming complexes with anions (eg, oxalate, phosphate) is reduced.
Xanthine oxidase inhibitors
Class Summary
A xanthine oxidase inhibitor is used to lower urinary uric acid. The doses provided in the table are for children with uric acid or calcium-urate renal calculi. Physicians treating gout, hyperuricemia, or uric acid nephropathy should consult other articles.
Allopurinol (Zyloprim, Aloprim)
Allopurinol decreases uric acid production. Administer before meals and with extra fluid orally. Maintain urine output at approximately 1.5 mL/kg/h with oral fluid unless this is contraindicated.
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Three groups of kidney stones are shown. Groups at left and center contain varying concentrations of calcium, phosphate, and oxalate. The group of stones on the right is composed of cysteine.
Tables
Mechanism of Stone Formation |
Drug |
Primary Stone Composition |
Crystallization of highly excreted, poorly soluble drug or metabolite causes stone formation. |
Phenytoin, triamterene, sulfonamides, felbamate, ceftriaxone, indinavir, ciprofloxacin, guaifenesin/ephedrine |
Drug or its metabolites |
Drug may increase the concentration of stone-forming minerals. |
1. Anti-cancer drugs 2. Glucocorticoid 3. Allopurinol (if used in tumor lysis) 4. Loop diuretics 5. Calcium and vitamin D |
1. Uric acid 2. Calcium 3. Xanthine 4. Calcium oxalate 5. Calcium |
Drug inhibits activity of carbonic anhydrase enzymes in the kidney, causing metabolic acidosis, hypocitraturia, and elevated urine pH. |
Topiramate, zonisamide, acetazolamide |
Calcium phosphate |
