Kidney pain: causes, treatment, and when to see a doctor


Kidney pain, also known as kidney pain, is caused by injury, damage, or infection to the kidneys . The kidneys are a pair of bean-shaped organs located on both sides of the spine that are responsible for filtering the blood and maintaining the correct balance of fluids and electrolytes in the body.

The pain can be described as dull and stabbing or sharp and severe, depending on the underlying cause. Although kidney pain is sometimes mistaken for back pain, the sensation is much deeper and is found higher in the upper back, just below the ribs.

Kidney pain can be classified as unilateral if one kidney is affected, or bilateral if both kidneys are affected. This can provide clues as to whether the problem is internal (occurs in the kidneys), prerenal (associated with an organ above the kidneys), or postrenal (associated with obstruction or deterioration below the kidneys).

Illustration by Alexandra Gordon, Get Meds Info


The causes of kidney pain are extensive and can be widely described as infection, trauma, obstruction, or growth.

Kidney infection

A kidney infection, also known as pyelonephritis , is usually caused by bacteria and can affect one or both kidneys. Acute pyelonephritis is a type that affects suddenly and severely, while the milder and recurrent cases are called chronic pyelonephritis.

Pyelonephritis is usually caused by an infection that has spread from the lower urinary tract, including the ureters, bladder, or urethra.

Acute pyelonephritis can often develop within two days. Symptoms include:

  • Unilateral or bilateral kidney pain, often dull and severe, felt in the side (back and sides), abdomen, or groin
  • High temperature (over 102 degrees Fahrenheit)
  • Body chills
  • Nausea and vomiting
  • Fatigue
  • Confusion
  • Painful or burning urination ( dysuria )
  • Cloudy or fishy urine
  • Blood in the urine ( hematuria )
  • Frequent urination (urge to urinate)

Chronic pyelonephritis is less severe, and in some cases, symptoms may be absent. If symptoms develop, they may include a dull pain in the side, accompanied by malaise and a low-grade fever.

Kidney injury

Kidney injury is the result of a forceful blow or penetrating wound that ruptures one or both kidneys. Due to the vulnerable position of the kidneys in the abdominal cavity, these injuries are not uncommon.

Up to 10% of abdominal injuries cause kidney damage. Car accidents, physical assaults, and heavy falls are the cause of most kidney injuries.

The problem with these injuries is that they are not always symptomatic. While some may be in pain, it may be dull rather than specific. There may or may not be signs of bruising or injury. However, touching the kidney area often causes pain.

Other common symptoms may include fever, blood in the urine ( hematuria ), inability to urinate, decreased activity, increased heart rate ( tachycardia ), and abdominal pain and swelling. Symptoms like these are urgently needed.

Kidney obstruction

Renal obstruction can occur in the kidneys or as a result of a blockage in the urinary tract. Those that affect the ureters can cause unilateral or bilateral pain. A blockage in the bladder or urethra tends to affect both kidneys.

Blockage, also known as obstructive uropathy, can be caused by a number of conditions, including:

When an obstruction occurs for any reason, the kidneys begin to swell, a condition called hydronephrosis . Symptoms include pain in the side, groin, or abdomen, as well as fever, dysuria, the urge to urinate, and nausea.

Symptoms can vary depending on the location and severity of the blockage. Kidney stones are usually the most painful, usually concentrated in the side and radiating to the abdomen and groin in waves. Others are less specific, but can worsen if the blockage is left untreated, resulting in fever, sweating, chills, vomiting, hematuria, and decreased urine output.

Kidney tumors or cysts

Kidney tumors or cysts generally do not cause pain, unless they grow in size or do not spread widely. The three most common growth abnormalities are:

In general, kidney tumors, whether benign or malignant, do not cause pain until their size disrupts the structure of the kidneys. It is at this stage that the pain is usually constant, painful, and can get worse over time.

The pain is usually unilateral and is accompanied by hematuria, visible (macrohematuria) or invisible (microscopic hematuria).

When it comes to cancer, persistent discomfort and unexplained weight loss are clear signs of advanced cancer.

PKD can also be asymptomatic until cyst formation causes structural damage to the kidneys. In addition to pain in the side, usually bilateral, polyclinic disease can cause progressive worsening of symptoms, including headaches, high blood pressure, hematuria, abdominal pain and swelling, recurrent kidney stones, recurrent urinary tract infections, and kidney failure .

Unlike many other kidney diseases, PKD is associated with excessive urination (polyuria) rather than urinary dysfunction. The most common form of PKD, known as autosomal dominant PKD, is symptomatic in patients between the ages of 30 and 40. Kidney failure develops in about 10% of cases.

When to contact a healthcare provider

People often assume that sudden flank pain is caused by a stretched muscle or overexertion, and in many cases it will be.

If your pain persists, worsens, or is accompanied by urinary symptoms or signs of infection , you should see your doctor as soon as possible. This is especially true if you have a high fever, chills, vomiting, or cannot urinate.

Even if a kidney infection is mild, it can sometimes progress to bacteremia if it is not treated. It is a condition in which a local bacterial infection spreads into the bloodstream and causes systemic and life-threatening symptoms, including irregular body temperature, shortness of breath, sudden drops in blood pressure, and shock.

Since acute pyelonephritis can develop in as little as two days, a quick response is essential.

The same applies if you experience a dull but persistent pain along with unusual symptoms such as painful urination, chronic fatigue, or unexplained weight loss. None of this should be considered normal and you should not wait until there is visible blood in your urine to seek help.

If you are pregnant, do not assume that persistent back pain is related to pregnancy. Notice a dull ache in your lower back or on the sides of your back between your ribs and hips. If accompanied by symptoms of infection or changes in urination, call your doctor immediately.

This is especially true if you are suddenly unable to urinate. This could be a sign of an emergency that needs a blockage.


Only a medical exam can confirm the state of the kidneys or identify the cause of kidney pain. There are no reliable self-exams or tests to do at home. Diagnostic tools include laboratory and urine tests to evaluate your body's chemistry and imaging tests to identify and characterize the nature of the disease.

Laboratories and tests

Urinalysis is essential for the diagnosis of any kidney disease. A laboratory performs a complete urinalysis to evaluate your urine chemistry and look for any signs of kidney dysfunction, including excess protein , albumin , or red blood cells .

Abnormalities indicate a kidney problem. On the contrary, normal results usually allow ruling out that the cause is the kidney.

Blood tests will also be used to evaluate your kidney function. This includes:

  • Serum creatinine (SCr) , which measures the level of a substance called creatinine , which the body produces and excretes in the urine at a regular rate.
  • Glomerular filtration rate (GFR) , at which GFR is used to calculate the amount of blood that the kidneys filter.
  • Blood Urea Nitrogen (BUN) , which measures the level of a compound called urea, which is also produced and excreted in the urine at a constant rate.

Any abnormality in excretion indicates that the kidneys are not working properly.

If an infection is suspected, a blood test, known as an erythrocyte sedimentation rate (ESR) , can be used to check for inflammation, and urine culture can help isolate and identify specific bacterial or fungal infections.

Finally, a complete blood count (CBC) and liver function test (LFT) can offer additional information on whether the dysfunction is caused by an associated disease (such as high blood pressure, diabetes, or cirrhosis) or changes in blood chemistry. compatible with cancer. (There are no blood or urine tests to detect kidney cancer.)

Visual tests

Imaging tests are used as a means of indirect visualization of the kidney and surrounding structures. They can detect abnormalities in the shape or structure of the kidneys, identify cysts and solid tumors, or pinpoint the site of bleeding or obstruction.

Among the three commonly used tools for this:

  • Ultrasound uses sound waves to create high-contrast images of internal organs. This is often the first test done because it is quick, portable, and does not expose you to ionizing radiation. Ultrasound is especially helpful in differentiating cysts from solid tumors.
  • A computed tomography (CT) scan uses a series of x-rays to create a cross-sectional image of your kidneys. The test is ideal for detecting lesions, abscesses, stones, tumors, and other abnormalities that can be missed by ultrasound or X-ray. Although radiation is minimized, it can be up to 200 times greater than a standard chest X-ray.
  • Magnetic resonance imaging (MRI) uses a magnetic field and radio waves to visualize the kidneys, providing finer detail than CT or ultrasound. Although an MRI does not expose you to ionizing radiation, a radioactive contrast agent may be required to visualize certain tissues.

Other procedures

If imaging tests cannot provide a clear picture of a lower urinary tract obstruction or disorder, your doctor may recommend a procedure known as a cystoscopy . This involves inserting a flexible fiberoptic catheter into the urethra to view the bladder and is commonly used to diagnose bladder stones, cystitis , strictures , and cancer.

Cystoscopy is done under local anesthesia and can cause pain and minor bleeding. Infection is also possible.

If cancer is suspected, a biopsy may be done to obtain a sample of cells with suspicious growth. This can be done with fine needle aspiration (FNA), in which a narrow needle is inserted into the tumor using ultrasound, or with a core needle biopsy (CNB), which uses a thicker hollow shaft needle.

Both are about the same in their ability to correctly diagnose kidney cancer.

Differential diagnosis

People are often surprised at how high the kidneys are on their backs. In many cases, persistent pain is incorrectly attributed to the kidneys when it is actually a muscle or skeletal problem. To this end, healthcare providers often need to investigate other causes of "kidney pain" if urinalysis and other tests do not indicate impaired kidney function.

Examples include:

  • Eleventh or twelfth rib fracture, which can mimic kidney injury.
  • Lumbar or upper thoracic spine injury, in which pain in the spinal nerve may radiate to one side ( called reflected pain ).
  • Shingles (shingles) neuropathic pain in the side
  • Pleurisy , inflammation of the pleura (the lining of the lungs)
  • A retroperitoneal abscess is a severe purulent infection located between the anterior abdominal wall and the peritoneum (the lining of the abdomen).

Although some people believe that kidney pain is a sign of kidney failure , this rarely occurs. If you have chronic kidney disease (CKD) or acute kidney failure (ARF) , you are more likely to experience joint and muscle pain (due to toxin build-up and electrolyte depletion) than your kidneys.

Watch out

Treatments for kidney pain are as varied as the causes themselves. Serious illnesses generally require the help of a kidney specialist known as a nephrologist or a urinary tract specialist known as a urologist .

Kidney infection

Most kidney infections are bacterial and can be easily treated with broad-spectrum antibiotics . Fungal and viral infections are seen more often in people with weakened immune systems, including organ transplant recipients and people with advanced HIV.

Urine culture can help isolate the bacterial strain to select the most appropriate antibiotic. The most commonly prescribed antibiotics include ampicillin, cotrimoxazole, ciprofloxacin, and levofloxacin. Severe cases may require intravenous antibiotics instead of oral ones. For resistant bacterial strains, a combination therapy of antibiotics or stronger antibiotics such as carbapenem may be required.

During treatment, you should drink plenty of water to help urinate and flush your upper and lower urinary tract.

Kidney injury

Treatment of kidney injury is defined as follows:

  • Grade 1 kidney injury (kidney injury) or hematoma that does not expand (blood clot)
  • Grade 2 for a laceration less than 1 centimeter
  • 3rd degree for laceration greater than 1 centimeter
  • Grade 4 for breakage of more than 1 centimeter, causing internal bleeding.
  • Fifth degree: a torn or fractured kidney or a kidney with a blocked renal artery.

Minor injuries can often be treated with prolonged bed rest. More serious events may require surgery, including the placement of renal stents to open the blocked vessels. Selective embolism, in which a chemical or metal coil is used to block a blood vessel, can help stop bleeding.

In the worst case, a surgical procedure known as a nephrectomy may be required to remove one or, less commonly, both kidneys. Although it can function normally with just one kidney, you will need dialysis to remove both kidneys until an organ donor is found.

Kidney obstruction

Treatment is primarily aimed at removing the source of the blockage. This may include antibiotics to treat an infection, a nephrostomy (drainage of urine with a urethral catheter), or surgery if the stone cannot be removed on its own.

Severe hydronephrosis may require a percutaneous nephrostomy, a procedure in which a tube is inserted through the back to drain the kidneys directly. A ureteral stent can also be placed during cystoscopy to open a blocked ureter.

Additional treatment may be required to correct the underlying cause.

Kidney tumors or cysts

Depending on the results, treatment may include selective embolism to shrink the tumor (substantially depriving the tumor of blood necessary for growth) or nephrectomy to remove part or all of the affected kidney. Benign tumors are often treated in the same way as malignant tumors if they block the vessels or tubules within the kidney.

Cancer therapy depends on the stage of the malignancy, which depends on the size of the tumor, the number of nearby lymph nodes affected, and the presence of metastases (spread) of the tumor. Treatment options include next-generation chemotherapy, radiation therapy, immunotherapy , and targeted therapy .

There is no cure for PKD. Instead, treatment will focus on preventing complications (including high blood pressure, kidney infection, kidney failure, and brain aneurysm ) along with routine disease management.

Get the word of drug information

You should not ignore the development of kidney pain. Although over-the-counter pain relievers such as Advil (ibuprofen) or Tylenol (acetaminophen) can provide short-term relief, they cannot treat the underlying cause, which in some cases can be severe or asymptomatic.

The same goes for hydration . While drinking plenty of water or cranberry juice can help ease a mild urinary tract infection, it is not considered a cure. If you have questions about whether you need a healthcare provider, just call your healthcare provider's office or find out if your insurance company offers free telemedicine consultations.

On the other hand, if you experience sudden severe pain in the kidneys, whether there is blood, fever, nausea, or any other symptoms, you should seek emergency help without exception.

Frequently asked questions

  • Lateral pain occurs on the sides and back of the body, below the ribs, and above the pelvis. The pain is usually worse on one side of the body, but it can occur on both sides.

  • Sometimes it doesn't cause any symptoms. When this happens, you may feel pain in your side along with a fever, blood in your urine, dark urine, or frequent urination. It can also cause high blood pressure if it prevents the kidneys from filtering excess fluid from the blood.

  • In some cases, yes. Drinking enough fluids can prevent dehydration, which in severe cases can lead to kidney damage. Drinking water can make it harder for kidney stones to form because the crystals don't stick together. It is generally recommended to drink eight glasses of water a day, but this amount can vary depending on your age and health.

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