Testing · 29 October 2026 · 9 min read

Kidney disease symptoms: tests and how to protect them

Your kidneys rarely complain. You can lose a large part of their function without feeling anything, which is why chronic kidney disease is often found by chance, sometimes late. Here are the two simple tests that give the basic picture, who should have them, what protects your kidneys over the long run, and which medicines and habits can harm them.

Illustration of two pink kidneys, a test tube of blood and a urine sample cup on a pale blue background

In short

Chronic kidney disease (CKD) means the kidneys are damaged and cannot filter blood as they should. Many people have no symptoms, and the CDC says most people with CKD in the United States are undiagnosed.
Blood and urine tests are the only way to confirm it. A blood test shows how well the kidneys filter, and a urine test looks for albumin, a protein that leaks when they are damaged.
Diabetes and high blood pressure are the leading causes, so people with them, heart disease or a family history of kidney failure should be tested.
Controlling blood pressure is the most important step, along with managing blood sugar, staying active and not smoking.
Some long-term medicines, including anti-inflammatory painkillers (NSAIDs), can harm the kidneys, so ask before using them regularly.

The two tests to know

MedlinePlus says kidney tests check how well your kidneys filter waste from your blood and make urine. The two that matter most:

A blood test: the glomerular filtration rate (GFR), a common test for CKD that shows how well the kidneys are filtering. MedlinePlus also lists blood and urine creatinine, a waste product the kidneys normally remove.
A urine test for albumin: it detects protein leaking into the urine, which can happen when the kidneys are damaged.

The CDC explains that blood and urine tests measuring creatinine in the blood and protein in the urine are the only way to confirm CKD. MedlinePlus adds that an ultrasound can show the size and shape of the kidneys, and a biopsy can show the cause of kidney disease and how much damage there is. This guide does not interpret your own results. Ask your provider what they mean and how often to repeat them.

Who should be tested

MedlinePlus and NIDDK advise getting checked if you have diabetes, high blood pressure, heart disease or a family history of kidney failure. The NHS adds that people at high risk may be advised to have regular tests to catch CKD early.

The CDC says about one in three adults with diabetes and about one in five adults with high blood pressure have CKD, and CKD runs in families. It also lists obesity as a risk factor, because it raises the risk of high blood pressure and diabetes. If you are in any of these groups and have never been tested, ask your provider at your next visit.

Why kidney disease stays quiet

The NHS says CKD usually has no symptoms in the early stages and is often found by chance during a blood or urine test done for another reason. The CDC says as many as nine in ten US adults with CKD do not know they have it.

Symptoms appear later and can include tiredness, swollen ankles, feet or hands, shortness of breath, feeling sick and blood in the urine, according to the NHS. Pain in the kidney area is not among the symptoms the NHS lists, which is one more reason to rely on tests.

What protects the kidneys

Blood pressure: NIDDK calls controlling blood pressure the most important step. Take blood pressure medicines as prescribed, and ask your provider about your target.
Blood sugar: if you have diabetes, the CDC advises keeping blood sugar within your target range.
Healthy habits: eat healthfully, be more active and maintain a healthy weight, per NIDDK and the CDC.
Smoking: the CDC says quitting helps, because smoking can worsen kidney disease and reduce the effect of blood pressure medicine.
Medicines that protect: the CDC suggests asking your doctor about ACE inhibitors and ARBs, which may protect the kidneys as well as lower blood pressure.
Care team: if you have CKD, the CDC recommends including a nephrologist, a kidney doctor.

What can harm the kidneys

The NHS lists long-term use of certain medicines, such as lithium or NSAIDs, among the causes of CKD, along with high blood pressure, diabetes, high cholesterol, kidney infections and inflammation, inherited cysts and urine blockages such as recurring kidney stones or an enlarged prostate. Often several of these combine.

Practical steps: tell every provider and pharmacist about your kidney problem before a new medicine or supplement, avoid taking anti-inflammatory painkillers regularly without advice, and take medicines as prescribed.

Eating for your kidneys

If your kidneys are healthy, the advice is the same as for general health: nutritious food, activity and a healthy weight. NIDDK and the CDC say that if you have CKD, you should work with a provider or registered dietitian to build a meal plan that includes foods you enjoy and supports your kidneys.

Do not start a protein-restricted or other special diet on your own. What suits you depends on your kidney function, other conditions and medicines.

When to see a doctor and red flags

See your provider if you have persistent or worrying symptoms that could be caused by kidney disease, as the NHS advises, or if you are in a risk group and have not had your kidneys tested. The CDC notes that CKD can raise the risk of heart disease and stroke, and can progress to kidney failure that needs dialysis or a transplant, though not everyone progresses and treatment can slow it.

Red flags: passing little or no urine with weakness or confusion, severe breathlessness or chest pain need emergency care. Call 911.

Questions to bring:

Should I have my kidneys tested, and how often?
Could any of my medicines or supplements affect my kidneys?
What is my blood pressure target?
Do I need a dietitian or a kidney specialist?

Questions and answers

Which tests show how my kidneys work?

A blood test that estimates the GFR from creatinine, and a urine test for albumin. MedlinePlus lists both, with ultrasound and biopsy as other tools in specific cases.

Do I need to drink a lot of water for my kidneys?

None of the health bodies cited here sets a daily water target for protecting the kidneys. Ask your provider how much fluid suits you, especially if you have heart or kidney disease.

Are painkillers bad for the kidneys?

The NHS lists long-term use of NSAIDs such as ibuprofen among the causes of CKD. Occasional use as directed is different from taking them every day, so ask your provider.

Should healthy people cut back on protein?

None of the health bodies cited here advises limiting protein when your kidneys are healthy. If you have CKD, a dietitian can set an individual plan.

Do the kidneys hurt in chronic kidney disease?

Usually not in the early stages, according to the NHS, which is why testing is the only reliable way to know. Later signs include tiredness, swelling and breathlessness.

Sources

Sources checked on 29 October 2026.