Symptoms of kidney stones may include pain or pressure in the lower back, more frequent urination or urges to urinate, and nausea. However, symptoms may vary depending on the size of the stone.

Kidney stones are mineral deposits that form in the kidneys. They can vary in size, with some being as small as a grain of sand, and others being as large as a pebble. The size of the kidney stone does not always correspond to the severity of the symptoms a person might experience.

Small kidney stones may pass through the urinary tract without causing any symptoms. However, larger stones may become stuck in the urinary tract. This is usually the point at which a person will experience the first signs and symptoms of a kidney stone.

This article outlines the early signs and symptoms of kidney stones. We also discuss the causes of kidney stones, as well as their potential complications.

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Pressure or pain in the lower back may be an early symptom of kidney stones.

Kidney stones vary in size. Tiny stones are less likely to become stuck in the kidneys or other parts of the urinary tract. Mild to moderate symptoms may occur during the passage of a small stone, although many people may pass stones without experiencing any pain.

Larger stones may cause pain, bleeding, inflammation, or infection. However, these symptoms may not usually develop until the stone has started to move through the urinary tract.

Below are some early signs and symptoms that may indicate a kidney stone is moving through the urinary tract.

Pressure or pain in the lower back

In some cases, a stone may become stuck in the ureter. The ureter is the tube that carries urine from the kidney to the bladder. A blockage here causes urine to back up in the kidney, resulting in pressure and pain sensations in the lower back. These symptoms may occur on the left or right side, depending on which kidney is affected.

According to the University of Chicago, pain or pressure are usually the first signs of a kidney stone. In some cases, the symptoms may be very subtle and build up slowly. In other cases, they may come on suddenly, with no early warning signs.

This pain can be severe and may lead to nausea or vomiting, or both. People often experience sharp, stabbing pain, and common measures such as rest or lying down do not relieve it.

UTI-type symptoms

In some cases, a person with a kidney stone may notice symptoms similar to those of a urinary tract infection (UTI). These include:

  • more frequent urination or urges to urinate
  • pain or discomfort during urination
  • discolored urine
  • foul smelling urine
  • blood in the urine
  • fever

Anyone experiencing any of the above signs and symptoms should visit their doctor. The doctor can run tests to check the urine for signs of a UTI. If there is no infection present, the person may be passing a kidney stone.

When a stone is present along with an infection, this can be a serious medical concern which may prompt emergency treatment.

Gastrointestinal issues

A person who has a kidney stone may experience issues with their stomach and gastrointestinal (GI) tract. Some GI symptoms that could signal a kidney stone include:

  • nausea
  • vomiting
  • general stomach discomfort that does not go away

According to the American Kidney Fund, a person should see their doctor if they experience any of the above GI symptoms.

Kidney stones usually form when a person’s urine contains excessively high levels of certain chemicals.

We outline the four main types of kidney stones below.

Calcium stones

There are two types of calcium stones: calcium oxalate and calcium phosphate. Together, they account for around 80% of all kidney stones.

Struvite stones

Struvite stones account for around 10% of kidney stones. They are usually the result of chronic UTIs, which can make the urine more alkaline. This promotes the growth of large, branch-like struvite stones.

Uric acid stones

Around 5–10% of kidney stones are uric acid stones, which develop as a result of excess acid in the urine.

Cystine stones

Less than 1% of kidney stones are composed of the amino acid “cystine.” A rare inherited condition called “cystinuria” prevents the kidneys from reabsorbing cystine from the urine. People with this condition are at increased risk of developing cystine stones.

Anyone can develop kidney stones, though certain factors can increase a person’s risk. According to the American Urological Association (AUA), one significant risk factor is low urine volume. When a person is dehydrated, there is insufficient fluid to dilute the salts in their urine. This increases the risk of kidney stones forming.

Other risk factors include:

  • being male
  • being of white, non-Hispanic ethnicity
  • having a family history of kidney stones
  • consuming a diet high in animal proteins
  • taking certain supplements, such as vitamin C, and calcium
  • taking certain medications, such as diuretics, and antacids

The following medical conditions can also increase a person’s risk of developing kidney stones:

Most small kidney stones do not require treatment. They may pass out of the urinary tract with minimal, or at least tolerable, discomfort.

However, kidney stones that do not pass out of the body can cause complications if left untreated. These can include:

  • infections
  • blockage or narrowing of the ureters
  • a buildup of urine, which puts additional strain on the kidneys
  • increased risk of developing kidney disease

A person should talk to their doctor if they experience symptoms of a UTI, such as pain, fever, and frequent urination. The doctor will conduct tests to help determine whether the symptoms are those of a UTI or a kidney stone. In either case, a person may require treatment.

Additionally, if abdominal or back pain is so severe that it requires pain medication, or if a person experiences unrelenting nausea or vomiting alongside pain, they should seek medical care.

In order to diagnose a kidney stone, a doctor may order an imaging test, such as an ultrasound or CT scan. These tests can also indicate the size and location of the stone.

A urinalysis will determine if infection or blood is present in the urine, and a doctor will carry out a blood test to check for more severe signs of infection.

Small kidney stones may pass on their own without treatment. A doctor may recommend drinking more fluids to help flush the stone out of the system.

In some cases, the doctor may prescribe the medication Tamsulosin. This drug relaxes the ureter, making it easier for stones to pass. Some people may also require over-the-counter or prescription pain relief medication.

According to the AUA, a person should wait no longer than 6 weeks to pass a small kidney stone. They should seek medical attention sooner if they experience worsening pain or an infection.

In some cases, a doctor may recommend surgery to place a ureteral stent to allow urine to bypass the stone, with or without removing the stone at the same time. According to the Urology Care Foundation, doctors usually reserve surgery for stones that may have caused or lead to infection or stones that do not pass and block urine flow from the kidney.

Kidney stones do not always cause any specific early signs or symptoms. For some, the first sign may be pain or pressure in the lower back or abdomen, or symptoms similar to those of a urinary tract infection. People who experience such symptoms should see their doctor for a diagnosis.

Kidney stones that do not pass out of the body can cause extreme pain if left untreated. They may also increase a person’s risk of developing urinary tract problems and kidney disease. If in doubt, people should see their doctor.