Split renal function: Meaning in a Radiology Report

Also written as: differential renal function, relative renal function, split function

Split renal function is the share of your total kidney function that each kidney provides, measured on a nuclear medicine kidney scan.

What it means

Split renal function gives two percentages, one for each kidney, that add up to 100. It is measured on a kidney scan such as a renogram or a DMSA scan. A tracer is injected into a vein, and a gamma camera measures how much of it each kidney takes up. The kidney that takes up more is doing a larger share of the work of filtering your blood.

When it matters

A split of roughly 45 to 55 percent each is usually considered balanced. A lower share on one side can come from scarring, a blockage, past infection or a kidney that is naturally smaller. Doctors use it to judge whether a blocked kidney is losing function, and to plan surgery or kidney donation. It shows the balance between the kidneys, not their combined function, which blood tests measure. Repeat scans can track changes.

Questions to ask your doctor

What is causing the lower share on one side?
Is my overall kidney function normal on blood tests?
Should the split be measured again to see if it changes?

General information, not medical advice. What a finding means for you depends on your symptoms, your history and the images themselves, so talk your results through with a doctor.