Most people know their cholesterol and blood pressure. Far fewer know their UACR, even though it is a single urine sample and one of the earliest warnings of kidney damage. It is also one of the tests most often left off routine lab work.

This article explains what the urine albumin-to-creatinine ratio measures, how to read it, what can make a result look worse than it is, and why a confirmed high result deserves attention.

Albumin is a protein that belongs in the blood. Healthy kidney filters hold on to it. When the filters are damaged, some albumin leaks into the urine, a finding called albuminuria (the broader term proteinuria covers all proteins).

Because urine can be dilute or concentrated depending on how much you drink, the lab compares albumin with creatinine in the same sample. The result is a ratio in milligrams of albumin per gram of creatinine (mg/g). The National Kidney Foundation calls the UACR the primary way to diagnose albuminuria and the preferred first test for adults at higher risk, because it is the most precise.

A UACR adds something an eGFR blood test cannot. Kidney filtering can still look normal while albumin is already leaking. The 2024 KDIGO guideline asks clinicians to test people at risk using both a urine albumin measurement and an assessment of GFR.

Reading the numbers

The National Kidney Foundation groups results this way:

  • Under 30 mg/g: normal, or at goal, with the lowest risk
  • 30 to 299 mg/g: moderately increased
  • 300 mg/g or higher: severely increased

These line up with the A1, A2 and A3 categories used to stage chronic kidney disease, explained in our article on CKD stages. A UACR that stays at 30 or above for three months or more meets the definition of CKD even when eGFR is normal.

Most people with albuminuria feel nothing. The National Kidney Foundation lists foamy urine and swelling around the eyes, feet, ankles or belly as possible signs, but notes that most people do not notice symptoms at all. Testing is the only reliable way to know.

Why one high result is not a diagnosis

UACR results move around from day to day. The National Kidney Foundation lists several causes of a temporary rise:

  • Dehydration
  • High-intensity exercise
  • Fever or infection
  • A flare of heart failure

KDIGO adds blood in the urine, menstruation and a symptomatic urinary infection, and notes that women make less creatinine than men, which pushes the ratio a little higher. For that reason KDIGO recommends confirming a UACR of 30 or more with a first morning sample, collected when you are well and not menstruating. NIDDK likewise says a high result may be repeated one or two more times before conclusions are drawn.

Practical tips for an accurate sample: skip a hard workout the day before, do not test during a fever or a bladder infection, and tell the person drawing your labs if you are menstruating. Home dipstick tests can give a rough reading, but the National Kidney Foundation advises confirming a positive result with a quantitative lab test.

Who should be tested

NIDDK recommends yearly kidney testing, including urine albumin, for people with type 2 diabetes and for those who have had type 1 diabetes for more than five years. It also recommends checking for kidney disease in people with high blood pressure, heart disease or a family history of kidney failure, and asking your doctor how often.

Blood pressure guidance now leans the same way. A 2026 review of the 2025 AHA/ACC hypertension guideline notes that the guideline adds the UACR to the initial lab tests for people with high blood pressure.

Why a confirmed high result matters

Albumin in the urine is a marker for risk well beyond the kidneys. The National Kidney Foundation notes that a confirmed moderately or severely increased UACR raises the risk of kidney failure and of a heart attack or stroke. That is why the result can change treatment as well as follow-up.

The good news is that albuminuria responds to treatment. The National Kidney Foundation describes the main options:

  • ACE inhibitors or ARBs, usually the first choice, used one class or the other and not both
  • SGLT2 inhibitors, first developed for diabetes and later shown to protect the kidneys, with some approved for CKD without diabetes
  • Finerenone, a newer non-steroidal medicine approved for people with albuminuria and type 2 diabetes
  • Lifestyle steps, including stopping tobacco, working toward a healthy weight and limiting alcohol

Blood pressure control and a lower-sodium diet support all of these. Tracking UACR over time shows whether the plan is working: a falling or stable result is a good sign. Our article on diabetes and your kidneys covers how these medicines are used when diabetes is part of the picture.

When to call a doctor

Call your doctor if a UACR comes back at 30 mg/g or higher, if you notice new swelling in your legs, ankles or face, or if your urine becomes persistently foamy. Do not start or stop a blood pressure or diabetes medicine on your own because of one result.

Dr. Yana Shtern is board-certified in Internal Medicine and Nephrology, and labs are drawn in our office, which makes repeating a urine test simple. Our labs and tests and kidney care pages describe how results are followed. If you would like your own UACR explained, a complimentary meet and greet with Dr. Shtern is a good place to start.

This article is general information, not advice for your situation. Members can call the office with questions about their own care.