Kidney Kealth Tests

Tests to Check Your Kidney Health

Kidney health testing is how we catch problems early, track changes over time, and make sure treatment is truly working. At Kidney Konnect, we help our community understand the most common kidney tests—what they measure, what the results can mean, and what questions to ask next—so you can advocate for yourself with confidence.

About your kidneys (why testing matters)

Most people have two kidneys—each about the size of an adult fist—located near the middle of your back just below the rib cage. Even though they’re small, kidneys do big jobs: removing waste and extra water, helping make red blood cells, balancing minerals, helping maintain blood pressure, and supporting bone health.

Your healthcare provider may order kidney-related tests from time to time, and which tests are chosen depends on symptoms and other factors. The guide below reflects the most common test types you may see across routine checkups, risk screening, or follow-up care.

Blood tests (what’s happening in your bloodstream) Serum creatinine

Creatinine is a waste product that comes from digesting protein and normal muscle breakdown, and healthy kidneys remove it from the body. “Normal” creatinine ranges vary by age, sex, body size, and other factors, but in general a lower creatinine level is better; higher creatinine can be a sign of acute kidney injury (AKI) and/or chronic kidney disease (CKD).

Cystatin C

Cystatin C is a protein made by your body’s cells and cleared by the kidneys, so it can be another way to estimate kidney function. It can be used to calculate eGFR when needed, but it’s less common and may cost more; for this test, a lower number is better.

eGFR (estimated glomerular filtration rate)

eGFR estimates how well your kidneys remove waste from the blood and is commonly calculated using your creatinine level, age, and sex (and sometimes cystatin C). eGFR naturally decreases with age; for this test, a higher number is better, and in general eGFR below 60 can be a sign kidneys may not be working properly while eGFR below 15 is a marker of kidney failure.

In less common situations where a more accurate measure is needed, a clinician may order a measured GFR (mGFR).

BUN (blood urea nitrogen)

BUN measures a waste product from protein breakdown that kidneys normally remove from the body. “Normal” BUN values vary and often increase with age; BUN alone usually isn’t very helpful, so clinicians often interpret it alongside creatinine and eGFR.

Urine tests (what’s showing up in your urine)

Urinalysis

A urinalysis checks a urine sample in a few ways: a visual exam (like color/cloudiness), a dipstick test strip that changes color when certain abnormalities are present, and sometimes a microscope exam for a closer look. It can flag concerns such as high acid levels, albumin (protein), bacteria, blood, pus, or sugar.

uACR (urine albumin-creatinine ratio)

uACR measures the ratio of albumin (protein) to creatinine in urine. Healthy kidneys keep albumin in the blood while filtering creatinine into urine, so there should be little to no albumin in urine; uACR under 30 mg/g is considered “normal,” and a uACR of 30 mg/g or higher can be a sign of albuminuria.

24-hour urine collection

A 24-hour urine collection requires collecting all urine for a full day in a special container. It may be used for kidney stones, glomerular disease, or to measure kidney function, but it’s less common than spot urine tests and is often used as a next-step when other results are abnormal or in less common clinical situations.

Imaging tests (what your kidneys look like)

Ultrasound

An ultrasound uses sound waves to create an image of your kidneys or nearby organs. (see the generated image above) It can help identify differences in kidney size or position and detect possible blockages like stones or tumors, and it typically does not use IV contrast dye.

CT scan (computerized tomography)

A CT scan uses x-rays to create detailed images and can help find structural issues or obstructions. Some CT scans use IV contrast dye, which can be a concern for people living with kidney disease, so it’s worth discussing risks and alternatives with your care team.

MRI (magnetic resonance imaging)

An MRI uses magnets and radio waves to create detailed images and can help evaluate kidney structure and obstructions. It may also involve IV contrast dye (which can be a concern in kidney disease), and the scan may take about 20–90 minutes depending on what’s being imaged.

Other tests (when more detail is needed)

Kidney biopsy

A kidney biopsy removes one or more tiny kidney tissue samples for microscope review. A clinician may order a biopsy when blood/urine/imaging results don’t provide enough information, in certain kidney diseases (including nephrotic syndrome or glomerular disease), or if a transplanted kidney isn’t working well.

mGFR (measured glomerular filtration rate)

mGFR directly measures kidney filtering and can be more complicated and time-consuming than eGFR, which is why it’s used less often. It can be done in different ways, including methods that use a 24-hour urine collection or multiple blood samples over several hours.

Kidney Konnect “next step” CTAs

“Know your kidney numbers: eGFR + uACR”
“Ask your doctor for a kidney test panel”
“Understand my lab results”
“Get support navigating next steps”