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3 There isn’t only one type of kidney stone.
There are four major types of kidney stones: calcium stones, struvite stones, uric acid stones, and cystine stones.
These are the most commonly occurring type, accounting for approximately 80 percent of all kidney stones. Often, this is in combination with oxalate, though sometimes also with phosphate or other substances.
Also known as infective stones, these sometimes develop following repeated urinary tract infections. They are generally a mixture of magnesium, ammonium, phosphate, and calcium carbonate phosphate crystals. Though softer in nature, struvite stones can grow very large—even filling the contours of the kidney and taking up the entire space where urine collects—and are nicknamed ‘staghorn stones’ because of their bull horn-like shape.
Uric acid is something that is naturally produced when the body breaks down protein. Urine will be more saturated with uric acid when it becomes acidic. This is why people who consume high animal protein diets are more likely to form uric acid stones. Having gout, chemotherapy, or disorders involving a high cell turnover are also risk factors. Uric acid stones can be particularly tricky to diagnose: they don’t show up on X-rays, CT scans are usually required to make the diagnosis.
Accounting for only one percent of all kidney stones, this is the rarest type, and forms due to a genetic disorder that creates high levels of cystine in the urine. Because it’s an inherited condition, these stones can occur even in childhood.