---
title: "Kidney function tests: What to Expect | HealthAnswers"
description: "Kidney function tests measure creatinine and eGFR levels in a blood sample, detecting chronic kidney disease early and tracking kidney health."
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# Kidney function tests: What to Expect | HealthAnswers

Tests & investigations

Kidney function tests measure creatinine and eGFR levels in a blood sample, detecting chronic kidney disease early and tracking kidney health.

Written by HealthAnswers editorial team Medically reviewed by [HealthAnswers UK doctor review panel](https://healthanswers.co.uk/our-doctors/) Reviewed 3 July 2026

## Quick answer

What are kidney function tests? Kidney function is checked using creatinine and eGFR blood tests, which detect chronic kidney disease and help monitor the effects of certain medicines. Fasting is usually not required. A low eGFR result needs review by your GP, along with attention to controlling your blood pressure.

General UK health information, not a diagnosis. In an emergency call 999 ; for urgent advice use [NHS 111](https://111.nhs.uk/) (GP out-of-hours in Northern Ireland).

On this page 4 sections

## Key facts about the kidney function tests

- eGFR is an estimate of how well the kidneys filter blood.
- Creatinine levels rise when the kidneys are underperforming.
- Chronic kidney disease is often silent until it is advanced.
- Good blood pressure control helps protect kidney function.
- Some medicine doses need adjusting in chronic kidney disease.

## What kidney function blood tests measure

Creatinine is a waste product that builds up in the blood when the kidneys are filtering less effectively than they should. eGFR is then calculated from your creatinine level together with your age and sex, giving a more complete picture of how well your kidneys are working.

## Chronic kidney disease and eGFR

[Chronic kidney disease](https://healthanswers.co.uk/conditions/chronic-kidney-disease/) is classified into stages one to five based on your eGFR result. Regular monitoring helps to track the condition over time and slow its progression where possible.

## Protecting your kidneys

Controlling blood pressure and diabetes are two of the most important ways to protect kidney function. It also helps to avoid taking NSAID painkillers when advised against them and to stay sensibly hydrated.

## When you might be referred for kidney problems

You may be referred to a nephrology specialist if your kidney function is declining rapidly or if you have advanced chronic kidney disease. Adjusting the doses of certain medicines is also an important part of care when kidney function is reduced.

## ! When to speak to a doctor about the kidney function tests

See a GP if you have a reduced eGFR or a rising creatinine level. Call **111** for urgent advice when you are unsure what to do.

## Common questions about the kidney function tests

What is eGFR? eGFR stands for estimated glomerular filtration rate, a measure of how well your kidneys are filtering blood. A result below 60 that persists over time suggests chronic kidney disease. What causes kidney disease? Kidney disease has many possible causes, including diabetes, high blood pressure, glomerulonephritis and blockages in the urinary tract. Your GP will look for these when investigating an abnormal result. What are the symptoms of chronic kidney disease? Chronic kidney disease often causes no symptoms in its early stages. Later on it can cause tiredness, swelling and changes to how often or how much you urinate. Can damaged kidneys recover? Acute kidney injury can sometimes recover fully once the underlying cause is treated. Chronic kidney damage is usually managed to slow its progression rather than cured.

## Sources

- [NHS — Chronic kidney disease](https://www.nhs.uk/conditions/kidney-disease/)
- [NHS — Blood tests](https://www.nhs.uk/conditions/blood-tests/)

## How we reviewed this page

Medically reviewed by the [HealthAnswers UK doctor review panel](https://healthanswers.co.uk/our-doctors/)

First published 28 June 2026 Medically reviewed 3 July 2026 Next review due 3 July 2029 or sooner if NHS or NICE guidance changes

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