phosphate stones are less common than calcium
oxalate. It is common to find stones that
contain both calcium oxalate and phosphate crystals.
However, usually the stone is more than 50% calcium
a stone has a large content of calcium phosphate,
then medical causes should be investigated.
These include hyperparathyroidism and renal tubular
acidosis (RTA). If the kidneys cannot
eliminate acid produced by the body, then acidosis
may ensue. Signs of an RTA include a low serum
bicarbonate (of CO2), low urine citrate, and a urine
pH above 5.5.
with calcium phosphate stones are treated with
citrate. They tend to have multiple recurrent
stones and loss of bone density. Over time the
kidneys can become calcified; this is known as Nephrocalcinosis.