ACR – Reference Ranges, Indicators & Result Interpretation

The albumin-to-creatinine ratio (ACR) is a key indicator used to assess kidney health and detect early metabolic disorders. The test enables early identification of albuminuria, which is essential in the diagnosis and monitoring of chronic conditions such as diabetes and hypertension. By understanding reference ranges and interpreting ACR results in context, clinicians and patients can better evaluate kidney function and take appropriate steps in treatment and prevention.

How to interpret your ACR results

A urine albumin-to-creatinine ratio (ACR) is reported in milligrams of albumin per gram of creatinine (mg/g), and a lower number is better than a higher one. Because creatinine is excreted at a steady rate, dividing urine albumin by urine creatinine corrects for how concentrated or dilute your sample is on the day of collection. That correction is what lets a single spot or first-morning sample give a useful answer without a 24-hour collection.

A slightly raised ACR can point to early-stage kidney disease, while a very high ACR signals more severe disease; a very low value generally means your kidneys are filtering normally. Cleveland Clinic phrases the same idea in terms of cardiovascular risk: a normal result indicates very low risk of kidney failure, heart attack, or stroke, while a markedly elevated result puts you at severe risk.

One reading on one day is rarely enough. Albumin can spike briefly from things that have nothing to do with chronic kidney damage, so an abnormal first result is typically repeated. Two out of three abnormal results over a three-to-six-month window is the usual threshold for considering early kidney disease. To see how ACR fits with the other half of the standard kidney workup, our eGFR page covers filtration rate from the blood side.

Reading the number in context

The same ACR value can mean different things depending on whether it is a one-off or part of a pattern, and whether you have other risk factors. The bands below are the most widely used adult cutoffs.

Results usually come back within a day or two of sample submission. If yours falls outside the normal band, your clinician will almost certainly ask for repeat ACR testing and a blood estimated glomerular filtration rate (eGFR) to clarify what is going on.

ACR reference ranges and what each band means clinically

The numeric bands matter because they map onto different conversations with your clinician — not because crossing a line by one point changes your diagnosis.

A normal ACR — under 30 mg/g — usually means your kidney filters are holding albumin back as they should, with very low near-term risk of kidney failure, heart attack, and stroke. A provider may still ask you to repeat the test a few months later to confirm, especially if you have diabetes or high blood pressure that puts you in a higher-risk surveillance group.

The 30 to 299 mg/g band is where most of the early-detection value of ACR sits. Cleveland Clinic flags this range as a marker of higher risk for kidney failure, heart failure, and stroke; if a repeat result a few months later sits in the same range, kidney disease becomes the likely explanation. The NHS describes the same band as “slightly raised” and consistent with early-stage kidney disease.

When ACR is 300 mg/g or higher and confirmed on a repeat test, the interpretation shifts. Cleveland Clinic links this band to possible kidney disease and a severe risk of kidney failure, heart attack, or stroke. The NHS uses the phrase “very high ACR level” for more severe kidney disease in the same range. Persistent or rising albumin loss at this level is generally treated as a signal that cardiovascular complications are more likely as well.

Conditions that can cause a temporarily high ACR

A single elevated ACR does not by itself diagnose kidney disease, because several short-term factors can push urinary albumin up without any underlying kidney damage. This is the main reason repeat testing exists.

Common transient causes that MedlinePlus calls out specifically:

• Intense exercise in the hours before sample collection can briefly raise urine albumin
• Fever and acute illness drive systemic inflammation that can lift albumin levels
• Inflammation in the body from any cause is a recognized confounder
• Urinary tract infections (UTIs) can drive up urine albumin without kidney damage
• Gum infections (periodontitis) are listed as another inflammatory cause
• Hepatitis and other inflammatory conditions can also affect results
• Certain medicines can produce temporary increases — ask your clinician which of your prescriptions or supplements might matter

Two other situations are worth flagging before the test rather than guessing they won’t matter. Hemorrhoids that are bleeding and active menstrual periods can both contaminate the sample; MedlinePlus instructs patients to tell their provider before the test in either case.

Factors that aren’t transient but still color the interpretation include muscle density, diet, age, and race — all of which MedlinePlus lists as influences on the result. None of these change the test bands themselves, but they are part of why a borderline number is not a diagnosis on its own.

How ACR fits with eGFR in a complete kidney check

ACR measures one specific thing: how much albumin is leaking through your kidney filters. It does not measure how fast those filters are clearing the blood. That second number — estimated glomerular filtration rate (eGFR) — comes from a blood test for creatinine and is the standard partner to ACR in a kidney workup.

When ACR comes back abnormal, MedlinePlus describes the usual next step as ordering an eGFR blood test to help characterize kidney function more fully. Cleveland Clinic similarly notes that abnormal ACR results typically prompt additional tests aimed at diagnosing kidney disease. The two together give a more complete picture than either alone.

For the blood-side marker that goes into the eGFR calculation, our creatinine page covers what the blood number means on its own. The same albumin-loss concept also goes by an earlier name — microalbuminuria — which the NHS notes is another name for urine ACR.

ACR and eGFR can disagree, and that is medically informative rather than contradictory. ACR is used to look for signs of kidney disease in higher-risk groups, often before overall filtration starts to fall. Those groups include people with diabetes, high blood pressure, a family history of kidney disease, heart disease, those over 50, smokers, and those with obesity.

Steps that may help lower a high ACR

Because elevated ACR usually reflects early kidney filter changes, the realistic goal is to slow further albumin loss rather than chase a single number. MedlinePlus is explicit: if you are diagnosed with early kidney disease, there are steps you can take to reduce the amount of albumin in your urine and protect your health. Your clinician decides which steps fit your situation.

A few general directions emerge:

• Treat the underlying driver. Diabetes is the most common cause of kidney disease, and treating early kidney disease can keep it from getting worse. The NHS adds that well-managed diabetes makes complications such as high blood pressure — which itself can lead to kidney disease — easier to control or prevent.
• Manage blood pressure and other cardiovascular risks. MedlinePlus links higher or rising urinary albumin to greater risk of heart and blood vessel problems, framing kidney and cardiovascular risk as a single bundle to manage.
• Repeat the test on schedule. ACR is meant to be tracked over time, not interpreted from one reading. The NHS recommends checking ACR at diabetes diagnosis and then annually, or more frequently if levels are significantly raised.
• Discuss medicines and supplements with your clinician. Because certain medicines can raise urinary albumin transiently, your provider needs to know what you are taking to interpret results correctly.

Specific drug choices, dosing, and supplement decisions belong to a clinician who knows your full history.

Frequently asked questions

What is a normal albumin-to-creatinine ratio?

A normal urine ACR is less than 30 mg/g, which usually indicates a very low risk of kidney failure, heart attack, or stroke. Even a normal result may be repeated a few months later to confirm, particularly if you have a condition like diabetes that puts you in a higher-risk screening group.

What does a high albumin-to-creatinine ratio mean?

A slightly higher than expected ACR may indicate mild kidney disease, while a high uACR points to moderate or severe kidney disease. When ACR is 300 mg/g or higher and confirmed on repeat testing, you may have kidney disease and a severe risk of kidney failure, heart attack, or stroke.

Can a urinary tract infection cause a high ACR?

Yes. Urinary tract infections are one of the inflammatory conditions that can raise urine albumin without kidney damage being present. Gum infections (periodontitis) and hepatitis can act the same way, which is part of why abnormal ACR results are typically repeated rather than acted on immediately.

Can exercise affect ACR results?

Yes. Hard exercise may increase the amount of albumin in your urine for a short time, which is why intense workouts are usually avoided before sample collection. This is also one of the reasons a single abnormal ACR is not enough to diagnose kidney disease — temporary increases need to be ruled out.

Do I need to fast or stop eating meat before an ACR test?

You don’t fast, but you may be asked not to eat meat for a day before the test because meat can affect your creatinine levels. Intense exercise is also discouraged beforehand. Always check with your provider about preparation, including whether any medicines or supplements you take could affect your results.

How often should I repeat the test if my first result is abnormal?

An abnormal first ACR is usually followed by two more tests during the three to six months after the first result. If two out of three tests show abnormal albumin levels, early-stage kidney disease becomes the likely interpretation. Higher-than-normal results often lead to more frequent testing thereafter.

Is microalbumin the same as ACR?

They are closely related. Microalbumin refers to the small amounts of albumin measured in urine, and the test for it is also known as the albumin-creatinine ratio (ACR). The NHS notes that urine ACR is also called urine microalbumin.

What is the difference between ACR and eGFR?

ACR measures albumin leaking into urine and is run on a urine sample, while eGFR is calculated from a creatinine blood test and estimates how fast your kidneys filter blood. When ACR is abnormal, providers typically order an eGFR to characterize kidney function more fully.

When to talk to your doctor

ACR is a screening and monitoring test, so the most important conversations with a clinician happen around abnormal numbers and new symptoms rather than around a single normal result. Cleveland Clinic gives an explicit list of situations that warrant a call if you have kidney disease or an elevated uACR.

Reach out to a healthcare provider if any of the following apply:

• Your ACR is 30 mg/g or higher on a repeat test, especially if a previous result was also elevated
• Your ACR is 300 mg/g or higher, which Cleveland Clinic flags as severe risk for kidney failure, heart attack, or stroke when confirmed
• You notice changes to your peeing habits, including peeing more than usual, foamy urine, or blood in your urine (hematuria)
• You develop swelling in your hands, feet, or ankles (edema)
• You have dry or itchy skin, or darkening skin
• You feel persistently fatigued or experience nausea and vomiting without another clear cause
• You have diabetes and have not had an ACR test in the past year — annual testing is recommended in this group
• You have hemorrhoids that bleed or are menstruating around the time of a scheduled ACR test, so the sample can be timed or interpreted correctly

If your ACR result is abnormal, expect your clinician to order additional testing — including an eGFR blood test and likely repeat ACRs — rather than treating the first number on its own. That layered approach is how transient causes get separated from genuine early kidney disease.

References

• MedlinePlus (U.S. National Library of Medicine, NIH)
• Cleveland Clinic
• NHS (UK National Health Service)

Last reviewed: 2026-05-17