Proteinuria & Albumin Testing

Protein in the urine as a kidney-health signal

What it is

Healthy kidneys filter blood while retaining most proteins, such as albumin, in the bloodstream. Proteinuria refers to protein appearing in the urine, and the urine albumin-to-creatinine ratio (UACR) is a common way to measure it.

How it's used

Elevated urine albumin can be an early sign of kidney stress or damage, sometimes appearing before changes in eGFR. It is commonly used alongside eGFR to stage chronic kidney disease and assess risk of progression.

Limitations

Temporary factors such as intense exercise, fever, dehydration, or urinary tract infection can also raise urine protein, so results are generally interpreted alongside repeat testing and a healthcare provider's evaluation.