Kidney function tests: checking how well the kidneys filter

Kidney function tests include creatinine, BUN, GFR and urine tests. What they show, why surgeons and transplant teams in India need them and what to send.

Glossary term · Tests & reports

By Nikhil Sharma, Founder · Updated · How we write and check

Definition

Kidney function tests (also: KFT, Renal function tests, RFT): Kidney function tests are blood and urine tests, sometimes with imaging, that show how well the kidneys filter waste from the blood.

Kidney function tests show how well your kidneys are working. MedlinePlus groups them into blood tests, urine tests and imaging. Common blood tests include creatinine, blood urea nitrogen (BUN) and the glomerular filtration rate (GFR). Because early kidney disease often has no symptoms, testing is the only way to know. Indian specialists use these results to plan surgery, contrast scans and medicines.

Which tests are included?

  • Creatinine: a waste product the kidneys remove from the blood.
  • BUN: another kidney-related blood test.
  • GFR: shows how well the kidneys are filtering.
  • Urine albumin: checks for a protein that leaks into urine when kidneys are damaged.
  • Urinalysis: a general urine test.

Why do specialists need them before treatment?

  • Contrast dye used in angiography and some scans can affect the kidneys, as MedlinePlus notes for coronary angiography.
  • MedlinePlus lists kidney tests among common blood tests before surgery.
  • Doses of some medicines depend on kidney function.
  • For a kidney transplant, they describe the recipient’s current function and the donor’s fitness.

Who should be tested?

MedlinePlus advises testing for people with diabetes, high blood pressure, heart disease or a family history of kidney failure.

When sending results

Send results with units and reference ranges, and the dates of earlier results if you have them. A trend over time tells the specialist more than one reading.

Questions people ask

Is a kidney function test the same as a GFR?

GFR is one part. A full set of kidney tests usually includes creatinine and other blood and urine tests. The laboratory may calculate an estimated GFR from your creatinine. Send whatever your laboratory reported.

Do I need kidney tests for an MRI with contrast?

MedlinePlus advises telling the team if you have kidney problems before an MRI, especially if contrast may be used. The radiology team decides whether a recent kidney test is needed first.

Sources

General information, not medical or legal advice. Rules change: confirm with the official source. Your treating specialist decides on suitability, treatment and length of stay. How we write and check.

More glossary

Biopsy

A biopsy is the removal of a small piece of tissue so that it can be examined in a laboratory.

Blood group and cross-match

Blood grouping identifies a person’s ABO group and Rh factor; cross-matching tests donor blood against the patient’s blood before transfusion.

Complete blood count (CBC)

A complete blood count is a blood test that measures red blood cells, white blood cells, platelets, haemoglobin and haematocrit.

Coronary angiography

Coronary angiography is a procedure that uses contrast dye and X-rays, delivered through a thin catheter, to show blood flow in the heart’s arteries.

CT scan

A CT scan is an imaging test that uses X-ray equipment and a computer to create cross-sectional pictures of the inside of the body.

DICOM images

DICOM is the international standard for medical images and related information, used by X-ray, CT, MRI and ultrasound equipment.

Free Case Review

Send us your reports. We’ll do the rest.

A case manager reviews your reports, shares them with suitable accredited hospitals and comes back with treatment options, the specialists involved and written estimates — free, with no obligation.

Start your case review