Your kidneys filter your blood and make urine. When the urine becomes too concentrated with certain minerals — and not dilute enough to keep them dissolved — those minerals can crystallize and clump together into a hard stone. The stone can stay in the kidney quietly for a long time, or it can move — and when it moves, you'll know.
Kidney stones (medically called renal calculi or nephrolithiasis) range from the size of a grain of sand to a golf ball. Most people never know they have a stone until it starts moving from the kidney toward the bladder — which is when the pain begins. Smaller stones are often passed naturally; larger ones need medical help.
Americans will have a kidney stone in their lifetime
More common in men than women, though the gap is narrowing
Recurrence rate within 10 years without preventive treatment
Kidney stone rates have been increasing over the past 30 years
Your urine is a mixture of water, minerals, and waste products. Normally, urine has enough water to keep all these dissolved — just like sugar dissolves in hot tea. Problems start when the balance tips:
When you're dehydrated, your urine becomes concentrated — the same amount of mineral in less water. Minerals like calcium, oxalate, uric acid, and phosphate begin to exceed the point where they can stay dissolved (called "supersaturation"). Think of it like trying to dissolve a cup of sugar in a glass of water versus a cup of water.
Once supersaturation is reached, the minerals begin to crystallize — forming tiny particles. Your urine also naturally contains substances that inhibit this process (like citrate), but in some people these inhibitors are low, making crystals more likely.
If the crystal isn't washed out quickly — and conditions remain favorable — it grows layer by layer over weeks to months, eventually becoming a stone large enough to see on imaging. Stones in the kidney can remain there silently for years before causing any trouble.
Knowing what your stone is made of is one of the most important pieces of information in your care — it tells us why it formed and exactly what diet and medication changes will prevent the next one.
Most common
Calcium oxalate (by far) and calcium phosphate
Why it forms
High oxalate intake, low fluid intake, low urinary citrate, high calcium in urine (hypercalciuria), or absorbing too much calcium from food
Visible on X-ray?
Yes — appears bright white on CT and plain X-ray
Common misconception: Having a calcium stone doesn’t mean you’re eating too much calcium. In fact, reducing dietary calcium often makes calcium oxalate stones worse — because calcium in the gut normally binds to oxalate before it reaches the kidneys. Prevention focuses on fluids, reducing oxalate-rich foods, and ensuring adequate calcium intake at meals.
Why it forms
Acidic urine (low pH), high purine diet (red meat, organ meats, seafood), gout, diabetes, or obesity
Visible on X-ray?
No — uric acid stones are invisible on plain X-ray. Seen on CT scan. This is why CT is the gold-standard imaging.
Special feature
The only stone type that can be dissolved with medication — no procedure needed in many cases
Uric acid stones form when urine is consistently too acidic. Alkalinizing urine with potassium citrate and reducing purine-rich foods can actually dissolve existing stones over weeks to months — making correct stone type identification especially important.
Why it forms
Urinary tract infections caused by specific bacteria (Proteus, Klebsiella) that produce urease, which alkalinizes urine and creates struvite crystals
Who gets them
More common in women; also in people with recurrent UTIs, urinary catheters, or structural urinary abnormalities
Growth pattern
Can grow very rapidly to fill the entire kidney collecting system (staghorn calculus)
Important: Struvite stones must be completely removed — even small fragments left behind can harbor bacteria and seed new stone growth. They cannot be managed with medication alone. Treatment almost always requires procedure(s) and long-term antibiotic management.
Why it forms
A rare inherited condition (cystinuria) where the kidneys leak excessive cystine — an amino acid — into the urine, where it crystallizes
Who gets them
People born with the genetic disorder cystinuria — usually first diagnosed in childhood or early adulthood
Challenge
Very hard to break with shock waves; forms repeatedly despite treatment; requires lifelong management
Cystine stones are among the most challenging to treat because they recur frequently, are resistant to shock wave treatment, and require very high fluid intake (often 3–4 liters daily) plus medications to remain manageable. Dr. Bansal provides specialist metabolic management for patients with cystinuria.
Without knowing what your stone is made of, prevention is guesswork. The dietary advice for calcium oxalate stones is almost the opposite of the advice for uric acid stones. If you pass a stone, catch it in a strainer and bring it to your appointment — or ask that any removed stone be sent to the lab for analysis.
Kidney stones sitting quietly in the kidney don’t usually hurt. The pain starts when the stone begins to move. Understanding where a stone is on its journey helps explain where you feel pain and what treatment options are available.
A stone sitting still inside the kidney often causes no pain at all. Many are discovered accidentally on imaging done for another reason. Occasional dull ache in the flank (side) may occur when a stone partially blocks drainage within the kidney. Some stones can grow large in the kidney without ever causing pain — until they start to move.
The ureter is a thin muscular tube (only about 3–4 mm wide at its narrowest) connecting the kidney to the bladder. When a stone enters the ureter, it triggers powerful spasms as the ureter tries to push it down. This causes renal colic — waves of excruciating pain in the flank, back, or side that typically radiate toward the lower abdomen and groin. The pain can be so severe it causes vomiting. It comes in waves (hence "colic") as the ureter spasms and relaxes.
There are three natural narrow points where stones commonly get stuck: at the ureteropelvic junction (where the kidney meets the ureter), in the mid-ureter where it crosses over blood vessels, and at the ureterovesical junction (where the ureter enters the bladder). The ureterovesical junction is the narrowest and where most stones get stuck. Pain in the mid-ureter tends to radiate toward the mid-abdomen; pain near the bladder often causes urgency and burning with urination, which can be confused with a UTI.
Once a stone drops into the bladder, the severe flank pain usually stops. You may feel frequency, urgency, or discomfort in the lower abdomen or bladder area. The stone now needs to pass through the urethra — which is shorter and wider in women (easier) and longer and narrower in men. Stones in the bladder almost always pass spontaneously.
When the stone passes through the urethra, the entire episode ends. You may feel a brief sting or you may not notice at all. Catching the stone in a fine strainer (available at pharmacies) allows it to be analyzed in the lab — vital information for preventing the next one.
Anyone can develop a kidney stone, but several factors make it much more likely. Many of these are modifiable — which is why prevention is so effective.
The single most important risk factor. Concentrated urine is the common pathway for all stone types. People who live in hot climates, work outdoors, sweat heavily, or simply don't drink enough are at significantly elevated risk. People in the "Sun Belt" states have higher stone rates for this reason.
High sodium (salt) intake causes the kidneys to excrete more calcium in urine. High oxalate foods (spinach, nuts, chocolate, tea) raise oxalate levels. High animal protein raises uric acid and reduces citrate. A Western diet high in processed foods, sodium, and animal protein is a major driver of rising stone rates.
The strongest predictor of a future stone is having had one. About 50% of people who have one stone will have another within 10 years without preventive measures. After a second stone, the recurrence risk is even higher — and this is when metabolic evaluation becomes essential.
Having a first-degree relative with kidney stones roughly doubles your risk. Some causes are directly inherited (cystinuria, primary hyperoxaluria), while others involve inherited tendencies toward hypercalciuria (too much calcium in urine) that run in families.
Hyperparathyroidism (overactive parathyroid gland raises blood calcium), gout, inflammatory bowel disease (especially Crohn's disease — causes increased oxalate absorption), type 2 diabetes, obesity, recurrent UTIs, and renal tubular acidosis all significantly increase stone risk.
Topiramate (Topamax, used for epilepsy and migraines), calcium supplements taken without meals, high-dose vitamin C, acetazolamide, and some HIV medications can all promote stone formation. Always tell your urologist about all medications and supplements you take.
The classic kidney stone — a stone moving down the ureter — produces one of the most distinctive pain syndromes in medicine. But not all kidney stones present identically. Here’s what to watch for:
Intense, cramping pain in the side and back, below the ribs. Comes in waves lasting minutes to hours. Often described as the worst pain imaginable — comparable to labor contractions. May force you to pace, as no position relieves it.
Pain that moves from the flank down toward the lower abdomen, groin, or genitals as the stone travels lower. The location of pain often hints at where the stone is in the urinary tract.
Pink, red, or brown urine — or microscopic blood visible only on a urine test. Present in almost all kidney stone cases, though sometimes the stone blocks completely and no blood is visible.
The same nerve pathways serve the kidney and the gastrointestinal tract. Severe kidney pain almost always triggers nausea and vomiting — which also makes staying hydrated much harder during an episode.
When the stone approaches the bladder-end of the ureter, it mimics a urinary tract infection — causing urgency (sudden need to go), frequent trips, and burning with urination. This is often mistaken for a UTI.
Unlike the pain of appendicitis or peritonitis (where lying still helps), kidney stone pain is so severe and colicky that patients typically writhe, pace, or rock — nothing helps. This restlessness is a classic sign.
Fever plus a blocked kidney means infected urine is backing up — this is a life-threatening emergency called obstructive pyelonephritis. The blocked kidney must be drained urgently (usually with a stent or nephrostomy tube) and IV antibiotics started. Do not wait to see if the fever resolves.
If you cannot keep any fluid down, you're becoming increasingly dehydrated — which worsens the stone and puts your kidney at risk. You need IV fluids, IV pain medication, and monitoring.
Complete obstruction of both kidneys (or your only functioning kidney) is a urological emergency. Kidney damage begins within hours of complete blockage.
If over-the-counter pain relief (ibuprofen, naproxen) is not touching the pain and you're in agony, you need IV pain management. You don't need to suffer through a stone episode at home.
If you have a single kidney (from birth, surgery, or disease) and it becomes blocked by a stone, your only kidney's function is at immediate risk. This requires urgent evaluation and likely urgent intervention.
If your symptoms sound like a kidney stone, the workup is generally quick and straightforward. The goal is to confirm the stone, determine its size and location, and check for any signs of obstruction or infection.
A low-dose CT scan of the abdomen and pelvis without contrast dye is the most accurate test for kidney stones — it detects 98% of stones, including uric acid stones that are invisible on X-ray. It takes about 10 minutes, shows the exact size and location of the stone and any blockage, and is available in all emergency rooms. This is almost always the first imaging test ordered.
When urine doesn't fully empty from the bladder, stagnant urine becomes a breeding ground for bacteria. Recurrent UTIs in men should always prompt evaluation for BPH and urinary retention.
A plain abdominal X-ray (kidneys, ureters, bladder) can show calcium-containing stones. It's quick and involves less radiation than CT, but misses uric acid stones and small stones entirely. Mainly useful for monitoring a known stone's progress after initial CT diagnosis.
A urine dipstick or microscopy checks for blood (present in almost all stone cases), signs of infection (critical — infection plus blockage is an emergency), and urine pH (low pH suggests uric acid stones; high pH suggests infection or renal tubular acidosis). A 24-hour urine collection is done later as part of the metabolic workup to prevent future stones.
Check kidney function (creatinine, eGFR), calcium level (elevated calcium can indicate hyperparathyroidism — a treatable cause of stones), uric acid level, and electrolytes. These also help assess how much stress the blocked kidney is under.
When a stone is recovered — either passed naturally or removed during a procedure — it's sent to the laboratory for chemical analysis. This is the most direct way to know exactly what your stone is made of, enabling precise dietary and medication prevention advice for the future. Always try to catch a passed stone.
Treatment depends on the stone’s size, location, type, and your symptoms — and on whether there are complications like infection or blockage. Most people with a first stone episode will be observed initially. Those who need intervention have several excellent minimally invasive options.
For small stones with a good chance of passing on their own, watchful waiting — actively managing symptoms while the stone travels naturally — is both safe and effective. About 80% of small stones (<5 mm) pass within 4–6 weeks. The goal is to keep you comfortable and hydrated while the stone makes its journey.
Drink 2–3 liters (about 8–12 glasses) of fluid per day. More fluid means more urine, which helps flush the stone along. Water is best — avoid cranberry juice and grapefruit juice during this period.
Anti-inflammatory medications (ibuprofen, naproxen) are the most effective for kidney stone pain because they reduce the swelling and spasm in the ureter — not just the pain signal. Stronger prescription pain relief is available if needed. Applying a warm heating pad to the back and flank also helps.
Tamsulosin (Flomax) — normally used for prostate symptoms — relaxes the smooth muscle of the ureter, making it easier for the stone to pass and reducing spasm pain. Multiple studies show it speeds stone passage and reduces pain in stones 5–10 mm. Dr. Bansal prescribes this for most patients managing a stone at home.
Use a fine strainer (or even a coffee filter) every time you urinate. Catch the stone when it passes — it can be as small as a grain of sand or as large as a small pebble. Bring it to us for analysis so we can identify its composition and guide prevention.
If pain becomes uncontrollable, fever develops, you cannot keep fluids down, you haven't passed the stone within 4–6 weeks, or follow-up imaging shows the stone isn't moving — it's time for a procedure.
Extracorporeal Shock Wave Lithotripsy (ESWL) uses focused sound waves generated outside the body to break a stone into small fragments that can then pass naturally through the urine. No instruments are inserted into the body — you lie on a table while shock waves are aimed precisely at the stone using X-ray or ultrasound guidance.
You receive sedation or light general anesthesia. A machine called a lithotripter focuses 1,000–3,500 rapid shock pulses directly at the stone over about 45–60 minutes. The stone shatters into fragments (ideally sand-sized particles) that pass in the urine over the following days to weeks. Some temporary bruising over the treatment area is common.
ESWL works best for stones under 10 mm that are not too hard (Hounsfield units on CT can predict this) and in locations that allow easy fragment clearance. For larger or denser stones, ureteroscopy may be more effective in a single treatment.
Ureteroscopy is the most commonly performed kidney stone procedure. A thin, flexible camera (a ureteroscope — thinner than a pencil) is passed through the urethra, into the bladder, and up the ureter to reach the stone. No incisions are made anywhere. Once the scope reaches the stone, a very thin laser fiber is passed through it to break the stone into tiny fragments using pulses of laser energy (usually a holmium or thulium fiber laser). Fragments are either vaporized into dust or retrieved with a tiny basket.
Performed under general or spinal anesthesia, typically taking 30–90 minutes depending on stone size and complexity. Most patients go home the same day or after one night. A temporary ureteral stent (a thin plastic tube from the kidney to the bladder) is often placed for 3–10 days afterward to keep the ureter open while swelling resolves. The stent is removed in a brief office procedure — no anesthesia needed.
ESWL works best for stones under 10 mm that are not too hard (Hounsfield units on CT can predict this) and in locations that allow easy fragment clearance. For larger or denser stones, ureteroscopy may be more effective in a single treatment.The stent is a soft plastic coil that curls in the kidney and bladder to hold the ureter open. Common stent symptoms include: feeling like you need to urinate urgently even when you don't, going more frequently than usual, blood in the urine, and an uncomfortable sensation in the flank when urinating. These are all normal and resolve when the stent is removed. Over-the-counter anti-inflammatory medications and phenazopyridine (a bladder analgesic) help with stent symptoms. The removal itself takes about 30 seconds in the office and is much less uncomfortable than most patients anticipate.
PCNL is the most powerful kidney stone treatment — reserved for very large stones, staghorn calculi (stones that fill the entire kidney collecting system), or complex stones that can’t be adequately treated with ureteroscopy or shock waves. A small incision (about 1 cm) is made in the back, and a thin tube (nephroscope) is passed directly into the kidney through the skin. Stones are then broken up with laser or ultrasonic energy and removed through the tube — all through a hole smaller than your thumb.
A newer variation using a smaller access tract (4–5 mm instead of 10–12 mm for standard PCNL) achieves equivalent stone clearance for many stones in the 10–20 mm range with less bleeding and faster recovery. Dr. Bansal discusses the best approach for your specific stone at consultation.
Most people feel much better quickly after stone removal. Here’s what’s normal in the days following each type of treatment:
Blood in the urine is normal for several days after any stone procedure. It should gradually clear to normal-colored urine within a week. If you develop fever (over 38°C/100.4°F), shaking chills, inability to urinate, or severe worsening pain after a procedure — call us or go to the ER immediately, as this could indicate a post-procedure infection.
After ureteroscopy with a stent, the stent itself causes most of the discomfort — not the procedure site. Urgency, frequency, blood in urine, and flank discomfort when voiding are all expected with a stent and resolve completely once it’s removed. Stent removal in the office takes about 30 seconds using a flexible camera — most patients say it was much easier than they feared.
After PCNL, you’ll have a nephrostomy tube (a thin drain in your back) removed before leaving hospital, and a stent from kidney to bladder removed in the office within 1–2 weeks. Some flank soreness at the puncture site is normal — usually manageable with regular pain relief for 1–2 weeks.
Treating the immediate stone is the first priority. But without understanding why it formed, roughly half of stone formers will have another one within 10 years. This is why a metabolic evaluation is recommended for anyone who has had more than one stone, a large stone, a stone with a suspicious composition, or who has risk factors for recurrence.
The cornerstone of stone prevention. You collect all your urine over a full 24-hour period in a large container (provided by the lab). The lab then measures dozens of factors in that urine: volume, pH, calcium, oxalate, citrate, uric acid, sodium, potassium, creatinine, and more. This gives a complete picture of why your urine is forming stones — which specific imbalance is the culprit — and guides highly targeted dietary and medication recommendations. Two collections on separate days (often one on a normal diet, one after dietary changes) give the most useful information.
Serum calcium, phosphate, uric acid, parathyroid hormone (PTH), bicarbonate, and kidney function are checked. Elevated PTH, for example, may indicate primary hyperparathyroidism — a surgically curable condition that causes recurrent calcium stones. Elevated uric acid may confirm a gout-related stone mechanism. These findings change management significantly.
If a stone was passed or removed, its chemical composition is analyzed in the lab. This is the most direct guide to prevention — knowing what the stone is made of is the clearest signal about what dietary and medication changes will work best for you specifically.
Dr. Bansal recommends it for anyone with: a second kidney stone; a first stone with strong family history; struvite or cystine stones (always); very young patients (under 30); people with only one kidney; patients with metabolic conditions (gout, inflammatory bowel disease, hyperparathyroidism, diabetes). A first-time stone former with no risk factors may defer it — but should come back promptly if they have another stone.
Prevention is not just possible — it’s highly effective. The right combination of fluid intake, dietary changes, and sometimes medication can reduce recurrence risk by 50–90%. The specific advice depends on your stone type, so everything below should be tailored by Dr. Bansal after your metabolic evaluation.
More than any medication or dietary change, adequate hydration is the single most effective stone prevention strategy. The goal is to produce at least 2–2.5 liters of urine per day — which means drinking about 2.5–3 liters (roughly 10–12 cups) of fluid daily, more in hot weather or when exercising.
The easiest check: your urine should be pale yellow to clear. Dark yellow or amber means you’re not drinking enough. If you consistently have pale, high-volume urine, you’ve dramatically reduced your stone risk regardless of stone type.
Start each day with a large glass of water before coffee. Carry a water bottle everywhere. Set reminders if needed. Wake once at night to urinate? Drink a glass before going back to sleep — nighttime is when urine becomes most concentrated. Lemon water is especially good — lemon juice is high in citric acid, which directly inhibits stone formation.
When diet and fluids alone aren't enough — or when a metabolic abnormality requires medical correction — specific medications can significantly reduce stone recurrence. These are targeted to the specific problem identified on your metabolic workup.
| Medication | Stone type(s) it prevents | How it works | Notes |
|---|---|---|---|
| Potassium citrate | Calcium oxalate, calcium phosphate, uric acid, cystine | Raises urinary citrate (natural inhibitor); alkalinizes urine (prevents uric acid crystallization) | Most widely used preventive medication; taken 2–3× daily; can dissolve existing small uric acid stones |
| Thiazide diuretics (e.g., hydrochlorothiazide, chlorthalidone) | Calcium stones (especially with hypercalciuria — too much calcium in urine) | Reduces calcium excretion in urine by promoting calcium reabsorption in the kidney tubules | Very effective for hypercalciuria; monitor potassium levels (can cause low potassium) |
| Allopurinol | Uric acid stones; calcium oxalate stones (when uric acid is high) | Reduces uric acid production; also reduces uric acid crystal formation that can seed calcium stone growth | Well-tolerated; requires monitoring; also treats gout |
| Tiopronin (alpha-MPG) | Cystine stones | Chemically binds to cystine in urine, making it more soluble | For cystine stones not controlled by fluids and potassium citrate alone; requires monitoring for side effects |
| Antibiotics (long-term or cyclical) | Struvite (infection) stones | Suppress the urease-producing bacteria that create struvite crystals | Used alongside surgical clearance — antibiotics alone cannot dissolve struvite stones |
The most reliable signs are severe, cramping pain on one side of the back or flank that may radiate toward the groin, blood in the urine, and nausea. Sometimes people feel a sudden "gush" or brief sting when the stone actually passes through the urethra. When the severe flank pain stops abruptly and you feel an urgency to urinate, the stone has often dropped into the bladder. Always try to strain your urine to catch it.
Most stones that will pass do so within 4–6 weeks of symptoms starting. Small stones (<5 mm) often pass within days. If you still have significant pain and haven't passed a stone after 4–6 weeks, a procedure is usually recommended. Waiting indefinitely risks kidney damage from prolonged obstruction.
Many people are too uncomfortable to do much during an active stone episode. When pain is well controlled, normal activity is fine — there's no evidence that bed rest helps stones pass faster. Some studies suggest moderate activity (walking, light exercise) may actually help. Avoid vigorous exercise if you're taking strong pain medications.
The procedure itself is done under anesthesia — you won't feel anything. The main discomfort after ureteroscopy is from the ureteral stent, which causes bladder irritation symptoms for the days it's in place. After PCNL, there is some soreness at the back puncture site. Most people manage post-procedure discomfort well with oral pain relief and are back to light activity within a few days.
This depends on your individual metabolic workup — but generally, calcium supplements taken between meals can raise urinary calcium and promote stone formation. Calcium taken with meals binds to oxalate in the gut and can actually help. If you take calcium supplements for bone health, discuss timing and dose with Dr. Bansal. Getting calcium from food (dairy, fortified foods) is generally preferred for stone formers.
A stone sitting quietly in the kidney (an asymptomatic stone) does not always need immediate treatment. Small stones (10–15 mm) are generally treated proactively to prevent a painful episode or complications — and because removal is easier and more complete as an elective procedure than in an emergency. Dr. Bansal will advise based on the stone's size, location, and your individual risk factors.
Whether you’re seeking expert care for a urological condition or looking for a second opinion, we’re here to support you every step of the way. Reach out to schedule an appointment, ask questions, or learn more about personalized, minimally invasive treatment options tailored to your needs.
