Symptoms of Kidney Stones

The symptoms of kidney stones can vary depending on the size of the stone. For most, the telltale sign is the sudden onset of excruciating pain radiating from the side (flank) to the groin or inner thigh, which comes and goes in waves. This may be accompanied by pain during urination, the constant need to urinate, the inability to urinate, or blood in urine.

The symptoms of kidney stones vary little among the sexes. The sharp pain radiating into the groin may be felt in the labia (vaginal pain) or in the testes (testicular pain). Recognizing the early signs of kidney stones can help you seek the appropriate diagnosis and treatment based on the size and location of the stone.

How Long Do Kidney Stones Take to Pass?

The symptoms of kidney stones closely align with the four stages that a kidney stone is passed:

• Stage 1 is when the stone forms in the kidney.
• Stage 2 is when the stone moves into one of the tubes, called a ureter, that passes urine from the kidneys to the bladder.
• Stage 3 is when the stone enters the bladder.
• Stage 4 is when the stone passes from the bladder into the urethra, the tube through which urine exits the body.

This process can take days or weeks, depending on the size of the stone. Kidney stones between 1 and 5 millimeters (mm) usually take eight to 12 days to pass; those that are even smaller may pass without any symptoms.

Large stones over 5 mm take an average of 22 days or longer to pass and may require medical intervention if they cause an obstruction.

Symptoms: Stage 1 (Kidney Stone Formation)

While the acute (sudden, severe) symptoms of kidney stones are more common during stage 2, subtle symptoms may start to develop as early as stage 1.

Most of the time, the formation of a kidney stone doesn’t cause pain until it dislodges from the soft interior portion of a kidney, called the renal pelvis. This is the part of a kidney where urine collects before being passed to a ureter—and the site where most kidney stones commonly form.

During this stage, you may experience waves of lower back pain on either side of the spine where the kidneys are located. The intermittent pain, called renal colic, is caused by spasms as the walls of the renal pelvis are stretched.

The pain may be dull, like a back strain, or intense, like a kidney punch. The episodes tend to last one to four hours.

Many people will have no symptoms during stage 1, even with stones as large as 15 mm. Moreover, stones can remain in the kidneys for years without causing symptoms. They may manifest pain when they pass into the ureter.

Symptoms: Stage 2 (Before Passing)

Stage 2 is when people typically experience the “classic” symptoms of kidney stones, due to the complete or partial blockage of the ureter.

The passage of a stone can set off sudden, severe bouts of renal colic, which some experts describe as one of the strongest pain sensations known. The pain can sometimes be so intense that emergency treatment is needed.

Accompanying the acute pain may be symptoms like:

• Restlessness
• Sweating
• Paling of the skin
• Nausea
• Vomiting
• Fever and chills
• Blood in urine (hematuria)
• Cloudy or foul-smelling urine (if there is a kidney infection)
• Pain with urination (dysuria)

Where It Hurts 

With renal colic, the pain is mainly felt in the flank— the area on the side of the body that’s just below the rib cage and above the waist. In addition to flank pain, the passage of a stone into the ureter simultaneously triggers downward waves of radiating pain to the groin or inner thigh.

The radiating pain, known as referred pain, is caused when pain signals are transferred to nerves in the spine, called splanchnic nerves. These are the nerves that provide motor and sensory function to the abdomen and pelvis.

The acute waves of pain can last for 15 to 45 minutes.

In most cases, the acute pain will start to ease after 24 hours as tissues surrounding the stone begin to relax. Severe pain lasting more than three days is likely to require medical intervention.

Symptoms: Stage 3 (Bladder Obstruction)

As the kidney stone makes its way into the bladder, the pain may almost entirely cease. With that said, the reprieve tends to be short-lived as the refilling and emptying of the bladder pushes the stone toward the narrow passage, called the bladder neck, that connects to the urethra.

If the stone becomes stuck at this junction, you may feel intense pressure in the middle of the lower abdomen near your pelvis. This can lead to symptoms such as:

• Frequent urination (sometimes as often as every five to 10 minutes)
• Reduced urination with a weak urine stream
• Urinary retention (the inability to completely empty the bladder)

Symptoms: Stage 4 (Passing a Kidney Stone)

The final journey involves the passage of the stone into the urethra and out of the body. This can take several hours or days. To aid with the passage, your healthcare provider may prescribe a drug called Flomax (tamsulosin), which relaxes the smooth muscles of the urethra.

Pain is the central feature, although it tends to be far less severe than what was experienced in stage 2. There may also be pain with urination and minor bleeding as the stone scrapes against the walls of the urethra. Pain may linger for a couple of days after the stone has passed.

If the stone becomes lodged in the urethra, it can often be dislodged by waiting five to 10 minutes and bearing down hard while urinating. The stone may come out whole or in fragments.

When Is Pain Not a Kidney Stone?

Kidney stone pain can mimic other conditions and may require investigation by a urologist to rule out other potentially serious causes.

This typically starts with what is known as the STONE score. This system predicts the likelihood of kidney stones on a score of 0 to 13. The STONE scoring is based on five factors commonly seen in people with kidney stones, namely:

• Sex (with males being twice as likely to have stones than females)
• Timing (meaning the sudden, severe onset of pain of short duration)
• Origin (referring to a greater incidence of stones in White people)
• Nausea (a symptom seen in almost every case of kidney stones)
• Erythrocytes (meaning the presence of blood, specifically in urine)

A STONE score of 10 to 13 is highly predictive of kidney stones, with an accuracy of up to 89.6%.

Even so, additional tests may be needed to definitively diagnose a kidney stone and rule out other causes. This may involve a physical exam, urinalysis, and imaging studies like an abdominal ultrasound, X-ray, or computed tomography (CT) scan.

Differential Diagnosis

There are many conditions commonly explored in the differential diagnosis of kidney stones, some of which are far more serious. Testing for these ensures they are not missed.

These include common and uncommon conditions like:

Female Differential Diagnosis

The symptoms of kidney stones don’t vary much between people of any sex. However, kidney stones tend to be less common in females (due in part to the hormone estrogen, which reduces the crystallization of minerals that lead to stones).

Even so, evidence suggests that the gender gap is closing, with the incidence of kidney stones rising among females, especially young adult and adolescent females.

Among the conditions that can mimic kidney stones in females are:

Male Differential Diagnosis

In addition to being at a greater risk of the disease, males are vulnerable to kidney stones when seasonal temperatures are hot, suggesting a “kidney stone season” in men.

This is thought to be due to differences in male kidneys, which allow for greater water reabsorption during hot weather to avoid dehydration. This retention of fluid, in turn, increases pressure within the renal pelvis, which can dislodge a stone.

Studies have shown that, among men, emergency room visits for kidney stones are higher in the summer and lower in the winter. The same is not seen with women.

Among the conditions that can mimic kidney stones in men are:

How to Tell If a Kidney Stone Has Passed

The passing of a kidney stone is almost invariably met with a notable drop in pain and gradual normalization of urine color, usually within a couple of days. You may also find the stone or fragments of the stone when urinating.

When a kidney stone is passing, providers will often recommend that you pee through a tea strainer to catch any pieces. This confirms that the stone has passed and allows the stone to be analyzed in the lab to see what it is made of. This can help determine why the stone formed and what can be done to prevent stones in the future.

Although there may be lingering pain, it will also gradually subside. If it does not, see a healthcare provider, as you may have developed an infection or have more than one stone.

Research suggests that around 86% of kidney stones pass spontaneously without medical procedures. When a stone is large (over 6 mm in size), the likelihood of this drops to around 59%.

When You Have No Symptoms

The absence of symptoms does not mean that you are clear of kidney stones. In fact, many people have stones without knowing it, often for years or decades. If and when they do pass, they may be small enough to cause few, if any, symptoms.

This is especially true in females whose kidney stones are often found by accident during an unrelated imaging study. Even if the stone were to become dislodged, it would often be “softer” than stones in men and break up easily without incidence.

According to a 2021 review in Current Urology Report, males are more likely than females to have calcium oxalate stones, which are far harder than other types of kidney stones and less likely to break up. Females, on the other hand, are more likely to have struvite stones, which are larger but have a soft, crumbly texture.

Stone size is a key factor as to whether kidney stones are asymptomatic (without symptoms) or symptomatic (with symptoms). By and large, symptoms tend to occur with stones larger than 2 mm.

Recognizing Signs in Someone Else

The “classic” signs of kidney stones may be readily recognized in someone you know, but not everyone has “classic” signs. In some people, the symptoms may be nonspecific (meaning they can be attributed to many conditions) and include things like dull lower back pain, fatigue, loss of appetite, and gastrointestinal symptoms like diarrhea.

In the absence of hallmark symptoms, the two things to watch out for are changes in urination and flank pain that comes and goes. While neither of these will lead to a diagnosis of kidney stones, they may provide ample justification for a medical visit.

Factors that raise the likelihood of developing kidney stones include:

• Chronic dehydration
• Diets high in salt, whole-fat dairy, red meat, and saturated fat
• Family history of kidney stones
• Having obesity
• High caffeine or alcohol consumption
• High intake of vitamins D or C
• Lack of physical activity
• Smoking

Having these risk factors doesn’t mean that kidney stones are the cause—only a medical evaluation can determine that—but neither does the absence of risk factors mean that you are “safe” from kidney stones.

In the end, if you have flank pain and urinary symptoms you cannot explain, see your healthcare provider or ask for a referral to a urologist for a comprehensive evaluation.

Summary

Telltale signs of kidney stones include the sudden, severe onset of flank pain radiating to the groin or inner thigh. There may also be nausea, vomiting, frequent urination, changes in urine color, and reduced urination. Depending on the size of the kidney stone, it may take one to three weeks or more for the stone to pass on its own.

Kidney stones that are large, cause severe obstruction, or do not pass on their own within three to four weeks may need medical treatment to either break them up or remove them physically.