Kidney Stones

Why stones form, what a stone attack feels like, and the treatment options — from waiting it out to surgery.

What a kidney stone is

A kidney stone is a hard deposit that forms when minerals in your urine become concentrated enough to crystallize. Most are made of calcium oxalate. Others are made of uric acid, calcium phosphate, or — less commonly — struvite, which is linked to infection.

A stone sitting quietly in the kidney often causes no symptoms at all. Pain usually begins when the stone moves into the ureter, the narrow tube draining the kidney to the bladder, and blocks the flow of urine. The pressure that builds up behind the blockage is what hurts.

What an attack feels like

Stone pain typically comes on suddenly and in waves. It is often felt in the flank or side, and may travel down toward the groin as the stone moves lower. Many people describe it as the worst pain they have ever had. Nausea and vomiting are common. You may also see blood in the urine, feel a constant urge to go, or have burning with urination.

Pain that comes and goes in waves is characteristic. Changing position does not relieve it, which is one reason people with stones are often restless and unable to get comfortable.

How we work it up

Evaluation usually includes a urine sample, blood work to check kidney function, and imaging. A non-contrast CT scan of the abdomen and pelvis is the most accurate way to find a stone and measure it. Ultrasound is sometimes used instead, particularly in children, in pregnancy, or when we want to limit radiation exposure.

Two measurements drive the treatment decision more than anything else: how big the stone is, and where it sits.

Treatment options

Watchful waiting. Small stones — roughly 5 mm or less — pass on their own most of the time. We manage pain, sometimes add a medication that relaxes the ureter to help the stone along, and ask you to strain your urine so we can catch the stone and analyze it.

Shockwave lithotripsy (SWL). Focused sound waves delivered from outside the body break the stone into fragments small enough to pass. No incisions. Works best for smaller stones in favorable locations.

Ureteroscopy with laser. A very thin scope is passed up through the bladder to the stone, which is broken up with a laser and removed. Highly effective, and it can reach stones anywhere in the ureter or kidney. A temporary stent is often left afterward.

Percutaneous nephrolithotomy (PCNL). For large or complex stones. A small tract is made through the back directly into the kidney so the stone can be removed in larger pieces. This is the most effective option for big stone burdens.

Keeping stones from coming back

If you have made one stone, your chance of making another is meaningfully higher. The single most effective preventive step is fluid intake — enough to produce roughly 2 to 2.5 liters of urine a day, which for most people means drinking noticeably more than they currently do. Pale yellow urine is a reasonable target.

Other measures depend on your stone type, which is why we ask you to catch the stone. Reducing sodium helps most stone formers. Counterintuitively, cutting dietary calcium usually makes stones worse, not better — normal calcium intake with meals binds oxalate in the gut and keeps it out of the urine. For recurrent stone formers we may order a 24-hour urine collection to identify the specific metabolic driver and target it directly.