Kidney function tests
Informed by recognized medical guidance
Overview
Kidney function tests are a group of blood and urine tests that check how well your kidneys are working. Your kidneys filter waste and extra fluid from your blood, so these tests help doctors see if your kidneys are healthy or if there is a problem.
Key facts
- Kidney function tests can find kidney problems early, even before you have symptoms.
- The tests usually measure levels of waste products like creatinine and urea in your blood.
- A simple urine test can check for protein or blood, which may be signs of kidney damage.
Kidney function tests are very common. Doctors often order them as part of a routine health check or if you have conditions like high blood pressure or diabetes.
These tests are for anyone who may have kidney problems. You might need them if you have diabetes, high blood pressure, a family history of kidney disease, or if you take medicines that can affect your kidneys.
Symptoms
- You have not urinated for more than 12 hours
- Sudden, severe swelling in your face, hands, or feet
- Chest pain or trouble breathing
- Seizures or loss of consciousness
- ⚠You have blood in your urine
- ⚠You feel very weak or dizzy
- ⚠You have severe nausea or vomiting and cannot keep fluids down
- ⚠Your urine output drops sharply
Common symptoms
- Swelling in your legs, ankles, or feet
- Feeling more tired than usual
- Changes in how much you urinate, or urinating more often at night
- Foamy or bubbly urine
- Itchy skin or dry skin
Symptoms in children
- Poor growth or slow weight gain
- Swelling around the eyes or face
- Frequent urination or bedwetting
Symptoms in older adults
- Confusion or trouble concentrating
- Loss of appetite
- Swelling in the legs or hands
- Muscle cramps
Causes
Main causes
- Diabetes (high blood sugar can damage the kidneys over time)
- High blood pressure (hypertension can strain the kidneys)
- Glomerulonephritis (inflammation of the kidney's filter units)
- Repeated kidney infections
- Blockages in the urinary tract, such as kidney stones or an enlarged prostate
Risk factors
- Having diabetes or high blood pressure
- Being overweight or obese
- Smoking
- Family history of kidney disease
- Being over 60 years old
- Long-term use of certain pain medicines (like ibuprofen or naproxen)
When to see a doctor
See a doctor urgently if:
- If you notice swelling in your face, hands, or feet that comes on quickly
- If your urine turns red or dark brown
- If you have a sudden drop in how much you urinate
- If you feel confused or very short of breath
Book a routine appointment if:
- If you have diabetes or high blood pressure, you should have kidney function tests at least once a year
- If you have a family history of kidney disease, talk to your doctor about how often to be tested
- If you are over 60, ask your doctor about routine kidney check-ups
Diagnosis
Kidney function is usually checked with blood and urine tests. Your doctor may also order an ultrasound to look at your kidneys.
Tests that may be done
- Blood test for creatinine and eGFR (estimated glomerular filtration rate) – eGFR tells what percentage of kidney function you have
- Blood test for blood urea nitrogen (BUN)
- Urine test for albumin (a type of protein) or protein-to-creatinine ratio
- Urine test for blood or infection
- Imaging tests like ultrasound, CT scan, or MRI to see the size and shape of your kidneys
What to expect at your appointment
The blood test is just like any other blood draw – a small needle is used to take a sample from your arm. For the urine test, you will be asked to provide a sample in a cup. You may be asked to collect all your urine over 24 hours. The tests are painless and results usually come back in a few days.
Treatment
Treatment for kidney problems depends on the cause and how much kidney function you have lost. The main goals are to slow down any further kidney damage and manage the underlying condition.
Self-care at home
- Take your medicines exactly as your doctor prescribes, especially for diabetes and high blood pressure
- Drink enough water unless your doctor tells you to limit fluids
- Limit salt in your diet to help control blood pressure
- Avoid taking nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen without checking with your doctor
- Quit smoking if you smoke
Medical treatments
Your doctor may prescribe medicines to lower blood pressure, control blood sugar, or reduce protein in the urine. Some medicines help protect the kidneys from further damage. If your kidney function drops very low, you may need dialysis (a machine that filters your blood) or a kidney transplant.
When is surgery considered?
Surgery may be needed if you have a kidney stone or blockage, or if you receive a kidney transplant. The decision for surgery is made with your medical team.
Living with this condition
Most people with mild to moderate kidney function loss can live a normal life by following their treatment plan. You may need to see your doctor regularly for check-ups and blood tests.
Lifestyle tips
- Stay active – aim for at least 30 minutes of moderate exercise most days
- Eat a balanced diet low in salt, and possibly lower in protein (ask your doctor or dietitian)
- Limit alcohol and avoid smoking
- Monitor your blood pressure at home if recommended
- Keep a record of your weight and let your doctor know if you have sudden changes
Diet and exercise
Your doctor may recommend a kidney-friendly diet that limits sodium, potassium, and phosphorus. A dietitian can help you plan meals. Exercise helps control blood pressure and blood sugar, which protects your kidneys.
Mental health and emotional wellbeing
Learning you have kidney problems can be worrying. You may feel anxious or depressed. It is normal to have these feelings. Talk to your doctor or a counselor. You are not alone.
Prevention
You cannot always prevent kidney disease, but you can lower your risk by keeping your blood pressure and blood sugar under control, eating a healthy diet, drinking enough water, avoiding too many painkillers, and not smoking.
Vaccines
Getting vaccinated against flu and pneumococcal disease can help prevent infections that might further harm your kidneys. Ask your doctor which vaccines are right for you.
Screening programmes
If you have diabetes, high blood pressure, or a family history of kidney disease, regular screening with blood and urine tests can catch problems early. Ask your doctor how often you should be tested.
Complications
If left untreated
- Chronic kidney disease can progress to kidney failure (end-stage renal disease), requiring dialysis or a transplant
- High blood pressure can get worse and increase your risk of heart attack or stroke
- Fluid buildup can lead to swelling and shortness of breath
- Anemia (low red blood cells) can cause fatigue and weakness
- Bone disease and mineral imbalances
Long-term outlook
The outlook for people with kidney problems is often very good, especially when caught early. Many people live full, active lives with proper treatment and lifestyle changes. Even if kidney function continues to decline, treatments like dialysis and transplant can help you live for many years. Your healthcare team will work with you to give you the best possible care.
Find support
International organisations
Local organisations
- Kidney Care UK ↗ · United Kingdom
- American Kidney Fund ↗ · United States
External links open third-party websites. Ruqelo Health is not responsible for external content. Listing an organisation does not imply endorsement.
Always verify with your doctor
Health guidelines vary by country and region. The information in this article is based on international clinical guidelines but may not reflect the specific guidelines, medications, or practices in your country. Always discuss your health concerns with your own doctor or healthcare provider, and refer to your local national health guidelines where available.
Important notice This information is for educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. If you are experiencing a medical emergency, call your local emergency services immediately.
Related conditions
Sources and guidance
This article is educational and is prepared with reference to recognized health information and clinical guidance sources where available. Specific source links may vary by topic.
Last updated: July 16, 2026
Educational note: This information is for education only and is not a diagnosis.
Use it to support, not replace, advice from a licensed clinician.
If symptoms are severe, worsening, or urgent, call your local emergency number or seek emergency care.