Capillary nail refill test

What Is a Capillary Nail Refill Test?

A capillary nail refill test is a quick and simple medical procedure that assesses how quickly blood flows through a finger or toe by measuring the time taken for the affected area’s skin to change colour when pressed. The test looks at the speed at which blood flows through capillaries, which are small tubes that make up the body’s circulatory system.

Preparing for a Capillary Nail Refill Test

No special preparation is required for a capillary nail refill test. You will be asked to remove any jewellery before the test begins.


Your doctor will perform the test by lightly pressing the tip of your finger or toe and timing how quickly the affected area blanches (turns white). The doctor will then lift their finger and time how quickly the colour returns.

Types of Capillary Nail Refill Test

A capillary nail refill test can be used to diagnose several medical conditions, including dehydration, low blood pressure, sepsis (an infection cause by a bacterial infection), and diabetes.

What an Abnormal Result Can Mean

If the blood does not return to the affected area as quickly as it should, this may indicate a medical condition. A doctor can use the results from the capillary nail refill test to help diagnose the underlying cause.


There is normally no risk associated with capillary nail refill tests. In rare cases, the affected area may become sore or tender for a short while after the test is complete.

When to Get Tested

A doctor may suggest a capillary nail refill test if they suspect you may have an underlying medical condition. The test can help a doctor make an accurate diagnosis.

Why This Test Is Performed

A capillary nail refill test can provide your doctor with useful information about your circulatory health in a short amount of time. This can be especially helpful in an emergency situation when a diagnosis needs to be made quickly.