Kidney Pain vs. Back Pain

Kidney pain is a specific type of back pain arising from the kidney and causing symptoms in the flank. The flank is a rectangular area in the back from the lower rib cage to the iliac crest (the top bone of the pelvis) and the spine to the lateral part of the body.

Back Pain Causes and Risk Factors

Back pain has numerous causes, depending upon the involved structure. Pain and inflammation of the muscles and ligaments in the back from an acute injury, or from chronic overuse, can cause significant pain.

Osteoporosis and decreased bone density can cause spontaneous compression fractures of vertebrae of the spine. Fractures (broken bones) may also occur due to trauma and acute injury.

The spinal nerves that exit the back can become irritated for a variety of reasons that cause the nerve to be inflamed. These include ruptured discs and arthritis of the back and narrowing of the spaces between the vertebral bodies. A common example is sciatica, inflammation of the sciatic nerve that causes pain in the back that may radiate down the leg.

Tumors can affect all structures that make up the back and cause pain. Those tumors may be benign or malignant. They can be primary, arising from the back structure, or metastatic, having spread from another part of the body.

All the structures located in the area of the back have the potential to become infected and cause pain. Some examples include the following:

• Shingles, a complication of chickenpox, which is an infection of the nerves
• Osteomyelitis, bone infection of the vertebral body
• Discitis infection of the discs located between the vertebral bodies

Kidney Pain Causes and Risk Factors

Inflammation of the kidney causes kidney pain and is most often due to a kidney infection, bleeding inside or surrounding the kidney, or obstruction of the kidney.

Kidney infection, or pyelonephritis = pyelo (central structure of the kidney called the renal pelvis) + neph or renal (kidney) + itis (inflammation), can be a result of a bladder infection in which the bacteria climb up the ureter to invade the kidney. Infection may also enter the kidney through the bloodstream should there be an infection elsewhere in the body.

Bleeding in and around the kidney may occur because of an injury (trauma) or may occur spontaneously in people who take anticoagulation (blood thinning) medication. Kidney tumors may also cause bleeding in the kidney.

Kidney pain from obstruction is most often due to kidney stones, but blood clots and tumors can also prevent urine from draining from the kidney down the ureter into the bladder. The kidney continues to make urine, even if it can't easily drain. This causes the kidney to swell and become inflamed, causing pain. Too much swelling and inflammation within the kidney may cause that one kidney to stop working. Fortunately, most people have another kidney to help remove waste from the body.

Back Pain Symptoms

Unless there is an acute injury, most mechanical back pain from muscles, ligaments, or bone will arise gradually and will be localized to the area of inflammation and strain.

Pain from nerve inflammation will follow the path of the nerve as it leaves the back and travels elsewhere in the body. For example, sciatic pain tends to travel from the low back to the buttock and then down the leg. Should a nerve become inflamed, there may be numbness and tingling, and the muscles that the nerve controls may develop weakness.

Shingles can attack any nerve that leaves the spinal cord and it is associated with a blistering rash. Most often the pain will occur a few days before the rash becomes visible.

When back pain is due to infection, fever may be present. Because those causes of back pain associated with fever are very uncommon, it sometimes takes longer for the health care provider to make the diagnosis.

Kidney Pain Symptoms

Pain from the kidney usually has other symptoms associated with it. Regardless of the cause, people with pain from their kidneys also have nausea and vomiting. Other symptoms give clues to the reason for kidney pain, such as:

• If the pain is due to an infection, the flank pain tends to be constant, and there may be an associated fever and chills. Urine may appear dark or cloudy and smell foul. If there is an associated bladder infection, other symptoms might include frequent urination, the urgency to urinate, and painful urination. Blood may be in the urine, as well.
• People who have kidney stones tend to have colicky, intense pain, meaning that the severe pain comes and goes, and there may be episodes in which the pain is more tolerable. There may or may not be blood visible in the urine.
• Those with bleeding into or surrounding their kidney may have bloody urine. Tumors of the kidney, ureter, or bladder can cause blood in the urine.

The most important first step in helping make the diagnosis of back or kidney pain is for the healthcare provider to talk to the patient, take a history of the illness and examine the patient. Most often, this can help determine the cause of the back pain and direct what tests might be done to confirm the diagnosis.

If the concern is that the kidney is the cause of the pain, then a urinalysis or urine sample is most helpful and can help guide further testing. If the infection is a concern, urine and blood cultures may be helpful. Most often, patients begin antibiotics before culture results come back, but the results may allow a more specific antibiotic to be chosen.

If a kidney stone is a concern, the provider may choose to treat the patient based on the history, physical exam, and evidence of blood in the urine, especially if the patient has had kidney stones in the past. For patients with their first stone, imaging the kidneys may be appropriate. This can be done with an ultrasound or CT scan.

Regardless of the cause of kidney pain, the provider may choose to evaluate kidney function. Some blood tests include BUN (blood urea nitrogen), creatinine, and GFR (glomerular filtration rate).

If the back pain is thought to be due to bones, muscles, nerves, or other structures of the back, the health care provider may or may not need to image the back with plain X-rays, CT, or MRI scanning. Other tests depend upon the symptoms and potential underlying cause.

Healthcare providers are aware that back symptoms may arise from a source away from the back and the pain and may need to order tests that may not be directly related to the back.

There are numerous causes of back pain and the healthcare provider will help choose the most appropriate diagnosis and treatment path for the specific cause.

For strains of the back, rest, ice, stretching, and muscle strengthening may be all that is required. But if there is evidence of nerve inflammation, it may be necessary to explore other treatment options for pain and to prevent long-term complications.

Often it is difficult for people to know that pain is coming from their kidneys, but people with kidney stones have intense pain and often require a visit to the emergency department for pain control.

Some symptoms should alert the patient or family that they should seek care quickly.

• Symptoms of urinary tract infection, including urgency, frequency, pain with urination, and/or fever
• Back pain associated with nausea and vomiting
• Abdominal pain that radiates to the back or flank
• Blood in the urine is never normal and should not be ignored.
• Back pain with muscle weakness, numbness, or fever
• Difficulty or inability to urinate
• Loss of bowel control

The prognosis for these symptoms depends upon the cause of the pain.