of mild-to-moderate severity, their safety or efficacy has not yet been proven. They should be used only when parathyroid surgery cannot be undertaken. Estrogen has been reported to be useful in reducing serum and urinary calcium in postmenopausal women with primary hyperparathyroidism.

Hyperuricosuric Calcium Oxalate Nephrolithiasis

Allopurinol (300 mg/day) is the physiologically meaningful drug of choice in hyperuricosuric calcium oxalate nephrolithiasis resulting from uric acid over production because of its ability to reduce uric acid synthesis and lower urinary uric acid. Its use in hyperuricosuria associated with dietary purine overindulgence is also reasonable since dietary purine restriction is often impractical. Potassium citrate represents an alternative to allopurinol in the treatment of this condition. Treatment with potassium citrate (at a dose of 30–60 mEq/day in divided doses) may reduce the urinary saturation of calcium oxalate (by complexing calcium), and inhibit urate-induced crystallization of calcium oxalate.

Enteric Hyperoxaluria

Oral administration of large amounts of calcium (0.25–1.0 g four times/day) or magnesium has been recommended for the control of calcium nephrolithiasis of ileal disease. The replacement of dietary fat with medium chain triglycerides may be helpful in those patients who also have malabsorption. Patients may exhibit hypomagnesiuria due to impaired intestinal absorption of magnesium. Oral magnesium supplements, such as magnesium gluconate (0.5–1.0 g three times/day), may correct hypomagnesiuria.

A high fluid intake is recommended to assure adequate urine volume. Since excessive fluid loss may be present, an antidiarrheal agent may be necessary before sufficient urine output can be achieved.

Hypocitraturic Calcium Oxalate Nephrolithiasis

In patients with hypocitraturic calcium oxalate nephrolithiasis, potassium citrate treatment is capable of restoring normal urinary citrate,

lowering the urinary saturation and inhibiting crystallization of calcium salts. Since hypocitraturia is found in a number of different conditions, each will be addressed individually.

Distal Renal Tubular Acidosis

Potassium citrate therapy is able to correct the metabolic acidosis and hypokalemia found in patients with distal renal tubular acidosis. In addition, it is capable of restoring normal urinary citrate although large doses (up to 120 mEq/day) may be required in severe acidotic states.

Chronic Diarrheal States

Potassium citrate therapy is indicated for patients with hypocitraturia secondary to chronic diarrheal states. The dose of potassium citrate will be dependent on the severity of hypocitraturia in these patients. The dosages range from 60 to 120 mEq in three to four divided doses. It is recommended that a liquid preparation of potassium citrate be used rather than the slow-release tablet preparation since the slow-release medication may be poorly absorbed due to rapid intestinal transit time. In addition, frequent dose schedules (three to four times/day) for the liquid preparation are necessary since this form of the medication has a relatively short duration of biological action.

Thiazide-Induced Hypocitraturia

Thiazide therapy may induce hypocitraturia due to hypokalemia with resultant intracellular acidosis. Therefore, it should be a common practice to administer potassium supplementation, preferably in the form of potassium citrate, to patients receiving thiazide for treatment of hypercalciuria.

Idiopathic Hypocitraturic Calcium Oxalate Nephrolithiasis

This entity includes hypocitraturia occurring alone, as well as in conjunction with other abnormalities (e.g., hypercalciuria or hyperuricosuria). Stones formed in this condition are predominantly composed of calcium oxalate. Potassium citrate therapy may produce a sustained increase in urinary citrate and a decline in the urinary saturation of the calcium oxalate.