Last updated: 17 October 2026 | Medically reviewed by Dr Kiran Kumar JK, MBBS, MD (PGIMER), Founder and Director, on 17 October 2026
Your kidneys filter waste from the blood, balance fluids and minerals, and help control blood pressure. When kidney tissue is damaged repeatedly or over a long period, it can heal with scar tissue. This is known as kidney scarring, or renal scarring. Scarred tissue no longer filters blood, so extensive scarring can reduce kidney function and, over time, contribute to chronic kidney disease.
Scarring often causes no symptoms in its early stages. That is why it helps to understand the causes, the warning signs and the tests used to detect it. This guide explains each of these, along with how doctors manage the condition.
What Causes Kidney Scarring?
Kidney scarring develops when inflammation, infection, obstruction or reduced blood supply damages kidney tissue. Common causes include:
Injury: physical trauma to the kidney can leave permanent scarring.
Kidney infections (pyelonephritis): an infection that travels up from the bladder to the kidneys can leave scars, particularly after repeated or untreated episodes. Young children, particularly those with recurrent urinary infections or reflux, may be at higher risk.
Vesicoureteral reflux (VUR) and reflux nephropathy: in VUR, urine flows backwards from the bladder towards the kidneys. This mainly affects children and makes it more likely that a bladder infection will reach the kidneys. Scarring linked to reflux is called reflux nephropathy.
High blood pressure: long-standing high blood pressure can damage small kidney blood vessels and contribute to scarring over time.
Diabetes: persistently high blood sugar can damage the kidney’s filtering units and lead to fibrosis over time.
Kidney stones and blockages: large or recurrent stones, or other obstructions, can put pressure on the kidney and increase the risk of infection.
Glomerulonephritis: inflammation of the kidney’s filtering units, sometimes caused by immune conditions, can lead to scarring.
Medicines and toxins: long-term or heavy use of some medicines, including certain painkillers such as NSAIDs, can damage kidney tissue.
Kidney Scarring Symptoms
Mild scarring usually causes no symptoms. Many people only find out through a scan, or a blood or urine test done for another reason. When symptoms do appear, they are often linked to the underlying cause or to declining kidney function, and may include:
- High blood pressure, especially if it is new or hard to control
- Protein in the urine, which may make urine look foamy
- Blood in the urine (haematuria)
- Swelling in the ankles, feet or around the eyes due to fluid retention
- Fever, pain in the side or back, and burning when passing urine during a kidney infection
- Tiredness, poor appetite, itching or difficulty concentrating, which usually appear only when kidney function is significantly reduced
In children, repeated urinary infections, unexplained fevers or poor growth should prompt a medical review. Because these signs overlap with many other conditions, proper testing is needed to confirm whether scarring is present.
Diagnosis of Kidney Scarring
Doctors combine your medical history, blood pressure readings, blood and urine tests and imaging to detect scarring and assess how well the kidneys are working. The National Institute of Diabetes and Digestive and Kidney Diseases gives a useful overview of kidney function tests.
Blood and urine tests
- Serum creatinine and eGFR estimate how well the kidneys are filtering.
- Urine albumin-to-creatinine ratio (ACR) detects protein leaking into the urine, an early sign of kidney damage.
- Urine culture confirms infection where relevant.
DMSA renal scan
A DMSA renal scan is a specialised imaging test commonly used to detect kidney scarring and assess how much each kidney contributes to overall function. A small amount of a radioactive tracer is injected into a vein and taken up by healthy kidney tissue. Scarred areas absorb less tracer and show up as areas of reduced uptake on the images. It usually requires no special dietary preparation, uses a small amount of radioactive tracer and is commonly used in children after kidney infections. Your centre will give you specific instructions, including whether to drink fluids beforehand. At Kiran, you can book a DMSA scan in Bangalore for kidney imaging and reporting.
Ultrasound
Ultrasound is often the first test because it is quick and uses no radiation. It shows kidney size, shape, swelling and blockages, but it can miss smaller scars.
CT scan
A CT KUB (kidneys, ureters and bladder) is a non-contrast scan mainly used to detect kidney stones and blockages. A contrast-enhanced CT or CT urography can show scarring, structural problems and tumours in more detail. Contrast dye requires extra caution in people with reduced kidney function, so the radiology team will review your kidney blood tests and medical history before the scan. Tell the team if you take metformin or other diabetes medicines. You can read more about CT scan in Bangalore options at our centre.
Preparation
Preparation depends on the test. A DMSA scan and a non-contrast CT KUB usually need little preparation, while contrast scans may need a recent kidney function test and some fasting. Always follow the instructions given when you book, and tell the team if you are pregnant, breastfeeding or have had a reaction to contrast dye.
Kidney Scarring Treatment
Scar tissue cannot be reversed, so treatment aims to protect the healthy tissue that remains and slow any decline in kidney function. Treatment is planned by your doctor or nephrologist and depends on the cause and severity.
Treating the underlying cause
- Prompt antibiotic treatment of kidney and urinary infections
- Management of vesicoureteral reflux in children, which may involve monitoring, preventive antibiotics or, in some cases, surgery
- Treatment of kidney stones or blockages
Protecting kidney function
- Controlling blood pressure, often with medicines such as ACE inhibitors or ARBs, which also reduce protein loss in the urine
- Managing blood sugar carefully in people with diabetes
- Other kidney-protective medicines where your doctor considers them suitable
Lifestyle measures
- Reducing salt intake
- Staying well hydrated, unless your doctor advises a fluid limit
- Avoiding regular or long-term NSAID use unless your doctor has advised it
- Stopping smoking and limiting alcohol
- Maintaining a healthy weight and staying active
Regular monitoring
- Periodic blood and urine tests to track kidney function and protein levels
- Repeat imaging where your doctor needs to check for new scarring
With early detection and good control of the underlying cause, many people with kidney scarring keep stable kidney function for years.
Long-Term Risks of Untreated Kidney Scarring
If the cause of scarring is not addressed, damage can progress. Possible long-term effects include:
- Chronic kidney disease (CKD): gradual loss of filtering ability
- Kidney failure: in advanced cases, dialysis or a kidney transplant may be needed
- High blood pressure: scarred kidneys can raise blood pressure, which in turn causes further damage
- Heart and blood vessel disease: CKD increases cardiovascular risk
- Pregnancy complications: people with significant kidney scarring who are pregnant or planning pregnancy may need closer monitoring
Preventing Kidney Scarring
Not every cause can be prevented, but these steps reduce the risk:
- Seek prompt treatment for urinary infections, especially in children with fever
- Have children with repeated infections assessed for vesicoureteral reflux
- Keep blood pressure and blood sugar within the targets set by your doctor
- Use painkillers sensibly and avoid regular NSAID use unless your doctor has advised it
- Have regular kidney checks if you have diabetes, high blood pressure or a family history of kidney disease
The National Kidney Foundation offers further guidance on protecting kidney health.
Get personalised nutrition guidance and meal plans from one of the best dieticians in Delhi.
Conclusion
Kidney scarring is permanent, but its effects can often be limited when it is found early and the underlying cause is treated. Because scarring is frequently silent, regular blood pressure, blood and urine checks matter, particularly for children with repeated infections and adults with diabetes or high blood pressure. Accurate imaging, especially a DMSA renal scan, helps your doctor confirm scarring and plan the right care. Kiran Nuclear Medicine and PET-CT Centre provides DMSA, CT and related kidney imaging at its Banashankari and Indira Nagar branches, with reports prepared by experienced specialists for your treating doctor.
Frequently Asked Questions
Can kidney scarring be reversed?
No. Scar tissue is permanent. Treatment focuses on preventing new scarring and protecting the healthy kidney tissue that remains.
What is the best test for kidney scarring?
A DMSA renal scan is a specialised test commonly used to detect kidney scarring and measure how much each kidney contributes to overall function. Ultrasound, CT and blood and urine tests also play a part, and your doctor will choose based on the clinical question.
Can you live a normal life with kidney scarring?
Many people with mild or one-sided scarring live normally, especially when blood pressure is controlled and infections are treated promptly. Regular monitoring helps detect any change early.
Does kidney scarring cause pain?
Scarring itself is usually painless. Pain in the side or back is more often caused by an active infection, kidney stones or a blockage.
Is a DMSA scan safe for children?
Yes. A DMSA scan uses a small amount of radioactive tracer and is routinely performed in children after kidney infections. The tracer is cleared from the body through the kidneys and urine. The radiology team will give you any specific aftercare instructions.
How often should kidney function be checked if I have scarring?
Many people need checks at least annually, but the schedule depends on kidney function, protein in the urine and the underlying cause. Your doctor will set the right interval for you.
