Albuminuria and proteinuria are often used interchangeably, but they are not the same thing. Both conditions are related to chronic kidney disease (CKD), as well as heart disease and stroke. It’s important to understand the difference between albuminuria and proteinuria and what each can mean for your health.*

What is albuminuria?

There are three types of proteins normally found in your blood plasma. When your kidneys are healthy and functioning properly, they return these proteins to your bloodstream after your blood has been filtered. Your kidneys also send any wastes and excess fluids and minerals to your urine to be eliminated. 

Albumin is the most abundant of the proteins in your blood plasma. Albumin molecules are small, so when your kidneys are damaged, they are among the first to pass through to the urine. When small amounts of albumin are present in your urine, the condition is called microalbuminuria. 

Microalbuminuria does not always indicate kidney disease. An intense workout can cause a slight and temporary increase of albumin in your urine. If the increase lasts longer than three months, however, it is considered an indicator of kidney damage.

As the damage progresses and the albumin levels in your urine get higher, your condition transitions from microalbuminuria to macroalbuminuria, also known as proteinuria.

How is proteinuria measured?

Proteinuria is indicated by significant amounts of albumin in your urine. In this instance, significant means that you are excreting more than 150 milligrams (mg) of albumin in your urine per day. 

There are several ways to assess for proteinuria:

• Manual reading of a reagent strip (urine dipstick test) for total protein
• Urine protein-to-creatinine ratio (UPCR) test 
• Urine albumin-to-creatinine ratio (UACR) test

The 2012 Kidney Disease: Improving Global Outcomes (KDIGO) guideline on the evaluation and management of CKD recommends the UACR as the preferred test for both initial and follow-up testing.

What signs should I look for?

Microalbuminuria may carry no symptoms. By the time it has transitioned to proteinuria, however, you may experience swelling (edema) in your feet, ankles, face, hands, and abdomen.

Proteinuria is:

• An established indicator of CKD
• Associated with faster progression of CKD to kidney failure and the need for dialysis or kidney transplant
• Linked to a higher risk for cardiovascular events and death for people with and without diabetes

Whether you have noticeable symptoms or not, obtaining laboratory tests is the only way to confirm the condition. 

More information on the difference between proteinuria and albuminuria can be found on the Cleveland Clinic website.

*Smith, C. A. (2019, Oct.). Proteinuria and Albuminuria: What’s the Difference? MDedge: Clinician Reviews. https://www.mdedge.com/clinicianreviews/article/210146/nephrology/proteinuria-and-albuminuria-whats-difference