How would you manage a patient with recurrent calcium phosphate nephrolithiasis who has hypercalciuria, hypocitraturia, and a urine pH greater than 6.3?

Good question! Calcium phosphate stone formers are the second most common type after calcium oxalate stone formers. The underlying problem is an elevated urine pH. Your differential diagnosis will include primary hyperparathyroidism, renal tubular acidosis, medullary sponge kidneys and the use of alkalinizing medications such as carbonic anhydrase inhibitors, potassium citrate, or sodium bicarbonate.

Although these patients may have a CT picture that looks like calcium oxalate stones, they may a...