Kidney stones — what they are, how we treat them, how to keep them from coming back.

What's actually happening

Your kidneys filter about 40 gallons of blood every day, turning the waste into urine. When urine becomes too concentrated — or contains too much of certain minerals — these minerals can crystallize and stick together. Over weeks to months, those crystals can grow into stones ranging from the size of a grain of sand to larger than a marble.

The most common type (about 80% of stones) is made of calcium oxalate. Less common types include uric acid stones, struvite (infection) stones, and cystine stones. The type matters, because prevention strategies differ depending on which type you form.

Why it hurts so much

Stones often form silently in the kidney — you may never know they're there. The pain starts when a stone enters the ureter and blocks the flow of urine. The ureter stretches and goes into spasm, which causes the classic severe flank pain that radiates around to the groin. Nausea and vomiting are common. Many patients describe stone pain as worse than childbirth.

How we diagnose stones

If you're in the emergency room or the office with suspected stone pain, you'll typically get:

• A CT scan without contrast — the most accurate imaging for stones. It shows us how many stones you have, how big each one is, and exactly where they are.
• A urine test to look for blood and signs of infection.
• Basic bloodwork to check kidney function and calcium.

If you pass a stone at home, save it. Strain your urine and bring the stone to your next visit — we can send it to a lab to determine what type it is, which is the most important single piece of information for preventing future stones.

Treatment options

1. Watchful waiting / letting it pass

Stones 4 mm or smaller pass on their own about 80% of the time. Stones 5–6 mm pass about 50% of the time. Stones larger than 7 mm rarely pass without help. While you wait, we typically prescribe pain medication, anti-nausea medication, and sometimes an alpha-blocker like tamsulosin (Flomax) to help the ureter relax.

2. Ureteroscopy with laser lithotripsy (URS)

A small, flexible scope is passed up through the urethra, bladder, and ureter directly to the stone. A thin laser fiber breaks the stone into dust-sized fragments that wash out naturally. A temporary ureteral stent is usually placed for a few days afterward. This is the most common stone surgery today for stones in the ureter or kidney up to about 2 cm.

3. Shockwave lithotripsy (ESWL)

Targeted high-energy shockwaves from outside the body are focused on the stone to break it into pieces that you then pass naturally in your urine. Completely non-invasive. Best for small-to-medium stones (<1.5 cm) in a good location. Done under IV sedation; most patients go home within an hour or two.

4. Percutaneous nephrolithotomy (PCNL)

For very large stones (>2 cm) or complex stones that fill the kidney's collecting system, we make a small incision in the back and remove the stone directly through a scope. This is the most involved stone procedure but it's also the most effective for removing large stone burden in a single operation.

Preventing future stones

If you've had more than one stone — or even just one — you benefit from a full metabolic workup. This usually includes a 24-hour urine collection plus bloodwork, which tells us exactly why you're forming stones. Common results and what they mean:

• Low urine volume — the single most common finding. Fix: drink enough to produce at least 2.5 liters of urine daily (your urine should be nearly clear most of the time).
• High urine calcium — often genetic. Treatment is often a thiazide diuretic, not avoiding dietary calcium.
• High urine oxalate — reduce high-oxalate foods (spinach, rhubarb, beets, almonds, chocolate, black tea) but keep calcium normal or high.
• Low urine citrate — treated with potassium citrate.
• High urine uric acid — reduce meat intake, sometimes treat with allopurinol.

Universal prevention tips

• Drink more water. More water in dilutes everything. This alone prevents about 50% of recurrences.
• Go easy on salt. High sodium intake increases calcium in the urine.
• Eat calcium with meals — don't avoid it. Dietary calcium binds oxalate in your gut so less gets absorbed.
• Moderate animal protein. Large amounts of meat, fish, and eggs raise stone-forming acids.
• Lemon in your water. Citrate is a natural stone inhibitor. Real lemon juice, not lemonade from concentrate.