Kidney Stones: Symptoms, Causes, Types and When to Seek Help

A kidney stone can sit inside the kidney for months or even years without any symptoms at all. Then it moves, and most people who experience the pain describe it as one of the worst of their lives. The shift from no sAAymptoms to severe pain can happen in hours, which is why understanding what kidney stones are, what causes them and what to watch for is genuinely useful knowledge.

This article covers the full picture: what kidney stones are, why they form, how they feel when they move, the four main types and what can be done about them.

What are kidney stones?

Kidney stones are hard deposits of minerals and salts that form inside the kidneys when the urine becomes too concentrated. The technical term is nephrolithiasis or urolithiasis, depending on where in the urinary tract the stones are found. They range in size from a grain of sand to, occasionally, a stone large enough to fill a significant portion of the kidney, known as a staghorn calculus.

Small stones often pass on their own through the urine, sometimes without the person ever knowing they had one. Larger stones, or stones that become lodged in the ureter, the tube connecting the kidney to the bladder, cause significant pain and may require medical intervention.

Symptoms of kidney stones

A stone that remains still inside the kidney often causes no symptoms. Symptoms begin when the stone moves into the ureter and blocks or partially blocks the flow of urine. The characteristic pain is called renal colic.

Renal colic

Renal colic is typically described as a severe, cramping pain in the side and back, below the ribs. Unlike many other types of abdominal pain, it cannot be relieved by changing position, which is one of the features that distinguishes it. It tends to come in waves, worsening and easing over minutes, and usually radiates from the side of the back downward toward the lower abdomen, groin and inner thigh as the stone moves.

Other symptoms

•      Pain or burning during urination, particularly as the stone approaches the bladder

•      Urine that appears pink, red or brown, or is cloudy with an unusual smell

•      Urinating more frequently than usual, or feeling an urgent need to urinate

•      Nausea and vomiting, which are common alongside severe pain

•      Difficulty urinating, or only passing urine in small amounts

When symptoms suggest infection

Fever and chills alongside kidney stone symptoms require urgent medical attention. They suggest the stone may be accompanied by a urinary tract infection or, in serious cases, an infection that has spread to the kidney. This combination is a medical emergency and should not be managed at home.

The four main types of kidney stones

Calcium oxalate	Most common, around 80 percent	High oxalate in urine, low fluid intake, certain dietary factors
Calcium phosphate	Common, often alongside calcium oxalate	Certain metabolic conditions and medications
Uric acid	Roughly 5 to 10 percent	High purine diet, gout, dehydration, acidic urine
Struvite	Less common, often infection related	Chronic or recurrent urinary tract infections
Cystine	Rare, around 1 percent	Inherited condition called cystinuria

Knowing which type you have matters because prevention strategies are type specific. Someone with uric acid stones needs different dietary changes than someone with calcium oxalate stones. This is why saving and sending a passed stone for analysis is worthwhile, even though it may not be the first instinct in the moment.

What causes kidney stones?

Stones form when the concentration of certain minerals in the urine rises to the point where they begin to crystallise. Several factors contribute.

Dehydration

Insufficient fluid intake is the single most consistent risk factor. Concentrated urine provides ideal conditions for crystal formation. People who live in hot climates or who sweat heavily through exercise are at significantly higher risk simply because they lose more fluid.

Diet

A diet very high in sodium raises calcium levels in the urine. Very high protein intake, particularly from animal sources, increases uric acid and calcium excretion. Foods high in oxalate, such as spinach, nuts, chocolate and tea, can contribute to calcium oxalate stones in people who are susceptible. High sugar consumption has also been linked to stone formation.

Medical conditions

Several conditions raise the risk significantly, including:

•      Hyperparathyroidism, which raises calcium levels in the blood and urine

•      Gout, which increases uric acid

•      Inflammatory bowel disease, which affects oxalate absorption

•      Renal tubular acidosis and other metabolic conditions

•   Obesity, which alters the chemical composition of urine in ways that promote stone formation

•      Chronic urinary tract infections, particularly for struvite stones

Medications and supplements

Certain diuretics, calcium containing antacids taken in excess, high dose vitamin C supplements and some medications used for HIV or epilepsy can increase stone risk. Always mention any kidney stone history to a prescribing doctor when a new medication is being considered.

Family history and genetics

A family history of kidney stones roughly doubles the personal risk. Several rare inherited conditions, including cystinuria and primary hyperoxaluria, cause recurrent and early onset stones.

Risk factors at a glance

•      Insufficient daily fluid intake

•      History of previous kidney stones

•      Family history of kidney stones

•      Living in a hot climate or sweating heavily

•      A diet high in sodium, animal protein or oxalate rich foods

•      Obesity

•      Certain medical conditions including gout, IBD and hyperparathyroidism

•      Male sex, since men are affected more often than women, though the gap has narrowed

Diagnosis

If a kidney stone is suspected, a doctor will typically carry out some combination of the following:

•      Urine analysis, checking for blood, crystals, signs of infection

•      Blood tests, checking kidney function, calcium, uric acid and other relevant levels

•      Imaging, usually a CT scan without contrast, which is the most sensitive method. Ultrasound is used as an alternative, particularly in pregnancy to avoid radiation. X rays can detect some stone types but miss others.

•      Stone analysis, if a stone is passed, filtering the urine through gauze to capture and test it

Treatment options

Small stones: watchful waiting

Stones under about 5 millimetres in diameter often pass on their own within a few weeks. The main management is adequate fluid intake, pain relief and sometimes an alpha blocker medication, which relaxes the ureter and can help the stone pass more quickly. The doctor will usually arrange a follow up scan to confirm it has passed.

Larger stones or blockages

Stones over roughly 10 millimetres rarely pass without help. Several procedures are available:

•      Shock wave lithotripsy (SWL): Sound waves directed at the stone from outside the body break it into smaller fragments that can then pass through the urine. Usually performed as an outpatient procedure.

•      Ureteroscopy: A thin flexible camera is passed through the urethra and bladder into the ureter to locate and remove or break up the stone with laser energy. Used particularly for mid ureter and lower ureter stones.

•      Percutaneous nephrolithotomy (PCNL): Used for very large stones. A small cut is made in the back and instruments are passed directly into the kidney to break up and remove the stone.

•      Surgical removal: Rarely required with the availability of modern minimally invasive techniques.

Prevention

Staying well hydrated is the single most important preventive measure, with the target of producing at least two litres of urine per day. In practical terms this usually means drinking enough so that your urine is pale yellow rather than dark.

•      Reduce sodium intake, since sodium raises calcium excretion in the urine

•      Moderate animal protein, particularly red meat and shellfish, which raise uric acid

•      Maintain a healthy weight

•      Do not restrict dietary calcium unless specifically advised to, since low dietary calcium can paradoxically increase oxalate absorption and stone risk

•      Limit high dose vitamin C supplements, which the body converts to oxalate

•      If you have had stones before, follow the specific dietary guidance your doctor gives based on the type

Medications are sometimes prescribed for people with recurrent stones, particularly thiazide diuretics for calcium stones, allopurinol for uric acid stones and potassium citrate to alkalinise the urine.

When to see a doctor or go to emergency

Seek medical care promptly if you experience:

•      Severe pain in the side or back that you cannot manage

•      Pain accompanied by fever and chills

•      Vomiting that prevents you from keeping fluids down

•      Blood in the urine

•      Difficulty or inability to urinate

•      Pain in someone who has only one kidney

Fever alongside the pain of a kidney stone is a medical emergency. Do not wait to see whether it settles. An obstructed, infected kidney can deteriorate rapidly and requires urgent treatment.

Frequently Asked Questions

Q. How long does it take to pass a kidney stone?

A. A small stone, under about 5 millimetres, may pass within one to three weeks. Stones between 5 and 10 millimetres may take longer and are less likely to pass without intervention. Stones over 10 millimetres usually require a procedure.

Q. Can drinking more water dissolve a kidney stone?

A. Increased fluid intake helps prevent stones from forming and can assist smaller stones in passing through the urine, but it will not dissolve a stone that is already formed. Uric acid stones are a partial exception, since alkalinising the urine through medication can partially dissolve them over time.

Q. Is a kidney stone always painful?

A. Not always. A stone sitting inside the kidney without blocking the flow of urine may cause no symptoms at all and is sometimes found incidentally on a scan done for another reason. Pain arises when the stone moves into the ureter and causes obstruction.

Q. Can kidney stones come back?

A. Yes. Recurrence rates are significant: roughly half of people who have had one stone will have another within ten years without preventive measures. Following up on the cause and making appropriate dietary or medical changes substantially lowers the risk.

Q. What foods should I avoid to prevent kidney stones?

A. The answer depends on the type of stone. For calcium oxalate stones, limiting high sodium foods and moderating oxalate rich foods such as spinach and nuts is often advised. For uric acid stones, reducing high purine foods such as red meat and shellfish is important. A doctor or dietitian can advise based on your specific stone type.

Disclaimer

This article is for general information only and does not constitute medical advice, diagnosis or treatment. If you are experiencing severe pain, fever or difficulty urinating, please seek immediate medical attention.