What Is the Normal Range for Microalbumin Creatinine Ratio?

A microalbumin creatinine ratio below 30 mg/g (milligrams of albumin per gram of creatinine) is considered normal in adults, according to the widely used KDIGO (Kidney Disease: Improving Global Outcomes) classification system. Results at or above 30 mg/g signal that your kidneys are leaking more protein than they should, which can be an early warning sign of kidney damage. But the number on your lab report only tells part of the story, because a single elevated reading does not automatically mean something is wrong.

What the Test Actually Measures

Your kidneys filter blood all day, keeping useful molecules like protein inside the bloodstream while letting waste products pass into the urine. Albumin is the most abundant protein in your blood, and healthy kidneys allow only trace amounts of it to slip through. When the tiny filtering units in the kidneys become damaged, more albumin leaks out. The urine albumin-to-creatinine ratio (uACR, also called the microalbumin creatinine ratio) is a way of catching that leak early, before more obvious signs of kidney trouble show up.

The test works by comparing the amount of albumin in a urine sample to the amount of creatinine in the same sample. Creatinine is a waste product your muscles produce at a fairly steady rate and your kidneys excrete throughout the day. Dividing albumin by creatinine adjusts for how concentrated or dilute the urine happens to be at the moment of collection, giving a result that approximates how much albumin your kidneys are releasing over a full 24-hour period. The result is expressed in milligrams of albumin per gram of creatinine (mg/g).¹

Because it only requires a single urine sample rather than a cumbersome 24-hour urine collection, the uACR has become the standard screening tool for early kidney damage in routine medical care. Doctors typically request a first-morning void sample, which tends to be the most concentrated and gives the most consistent results.

The Three Categories and What They Mean

International kidney disease guidelines break uACR results into three tiers. These categories apply regardless of whether you have diabetes, high blood pressure, or another condition that prompted the test.

A1 (below 30 mg/g): Normal or only a mild increase. This is the range most healthy adults fall into. Your kidneys are filtering albumin the way they should.
A2 (30 to 300 mg/g): A moderate increase, often called “moderately increased albuminuria” (the older term was “microalbuminuria”). This level means your kidneys are leaking more protein than expected and warrants further evaluation.
A3 (above 300 mg/g): A severe increase, sometimes called “macroalbuminuria” or “severely increased albuminuria.” At this level, kidney damage is more advanced and treatment decisions become more urgent.

These thresholds come from the 2024 KDIGO guidelines, which are used worldwide to diagnose and classify chronic kidney disease.² The cutoff of 30 mg/g is not a magic number where suddenly something is “wrong.” Risk rises on a continuum. But 30 mg/g is the threshold at which clinical evidence consistently shows the risk of kidney disease progression, heart disease, and other complications begins climbing steeply enough to merit attention.

Why a Single Elevated Result Is Not a Diagnosis

If your uACR comes back above 30 mg/g, your doctor should not immediately diagnose you with kidney disease based on that one sample. KDIGO guidelines recommend confirming an elevated result with at least one repeat test, ideally using another first-morning urine sample, before making any clinical decisions.³ That repeat test is meant to reduce day-to-day variability and cut the risk of a false positive.

Albumin excretion fluctuates more than most people realize. Strenuous exercise in the hours before the test, a fever, a urinary tract infection, dehydration, or even an unusually high-protein meal can temporarily push the number above the normal cutoff. If you test after running a half marathon or while fighting off a bladder infection, the result could look alarming even though your kidneys are perfectly fine. Retesting once those temporary influences have cleared up can save you from unnecessary worry and follow-up procedures.

In practice, many clinicians look for two out of three elevated results over a period of three to six months before concluding that albuminuria is persistent. If two separate samples, collected weeks apart and under proper conditions, both come back elevated, the result is far more reliable than any single measurement.

Things That Can Throw Off Your Result

Beyond natural day-to-day fluctuation, a few specific situations deserve attention because they can produce misleading readings.

Urinary tract infections are a well-documented confounder. Research has shown that a UTI can influence albumin measurements in two ways: it can cause genuinely transient albuminuria that clears up after antibiotic treatment, and it can trigger false positive results on certain automated urine analyzers used in labs.⁴ If you know you have a UTI or symptoms that suggest one, mention it to your doctor before the uACR test. Retesting after the infection resolves gives a much clearer picture.

Heavy physical exertion in the prior 24 to 48 hours can raise albumin excretion enough to push the ratio above 30 mg/g in people with no kidney problems at all. Menstruation can also introduce protein into the sample if collection is not careful. High fever from any cause raises albumin excretion temporarily, as does severe emotional stress in some individuals. Heart failure can produce elevated readings because the kidneys are under pressure from fluid overload, not from intrinsic kidney disease.

The timing of the sample matters too. The recommendation to use a first-morning void exists because urine produced overnight tends to have more consistent albumin-to-creatinine proportions than random samples collected during the day, when hydration levels, activity, and posture all introduce noise. If your lab draws a random mid-afternoon sample, expect the result to be somewhat less reliable than a morning specimen.

What Elevated Albuminuria Means for Your Health

An elevated uACR that persists across multiple tests is more than a lab curiosity. It is one of the strongest early predictors of kidney disease progression, cardiovascular events, and overall mortality.⁵ The kidneys and the heart share a surprising amount of biology, and damage to the tiny blood vessels in the kidneys often goes hand in hand with damage to blood vessels elsewhere. That is why doctors treat persistent albuminuria seriously even when kidney function (measured by eGFR, a different blood test) still looks normal.

For people with diabetes, albuminuria is one of the earliest markers of diabetic kidney disease, which is the single most common cause of kidney failure requiring dialysis in much of the world. Catching it at the A2 stage and intervening with blood sugar control, blood pressure management, and medications that protect the kidneys can slow or even halt the progression toward more serious kidney damage. Several newer classes of medications, including SGLT2 inhibitors and certain GLP-1 receptor agonists, have demonstrated kidney-protective effects in large trials, and treatment decisions often hinge partly on the uACR level.

For people with high blood pressure but no diabetes, albuminuria signals that hypertension is already affecting the kidneys. Tightening blood pressure control is a straightforward step, and many clinicians will choose a blood pressure medication that also reduces protein leakage, such as an ACE inhibitor or an angiotensin receptor blocker.

Even in people without diabetes or hypertension, a persistently elevated uACR should prompt further investigation. Possible causes include glomerulonephritis (inflammation of the kidney filters), lupus, certain infections, and other systemic conditions. The ratio by itself does not tell your doctor why the kidneys are leaking protein, only that they are.

Who Should Be Tested and How Often

Not everyone needs regular uACR screening. Current guidelines generally recommend annual testing for adults with diabetes (both type 1 and type 2), adults with hypertension, and people who already have known chronic kidney disease. If you fall into any of those groups, the test should be part of your routine bloodwork once a year. Many people in these categories get it done automatically alongside other labs and never notice it as a separate test.

People with a strong family history of kidney disease, those with obesity, and those with cardiovascular disease may also benefit from periodic screening, though the exact interval depends on individual risk. If you have none of these risk factors and are otherwise healthy, routine uACR testing is not standard practice. The test is inexpensive and low-hassle, but mass screening in low-risk populations has not been shown to improve outcomes enough to justify it as a blanket recommendation.

For people whose initial test comes back in the A2 or A3 range and is confirmed on repeat testing, monitoring becomes more frequent. Doctors typically recheck the uACR every three to six months to track whether treatment is reducing the leak, stabilizing it, or whether things are getting worse. A falling uACR over time is a good sign, and researchers increasingly view changes in the ratio as a meaningful way to gauge whether kidney-protective therapies are working.⁵

How the uACR Relates to eGFR

You will often see the uACR mentioned alongside another test called eGFR (estimated glomerular filtration rate), and it is worth knowing how the two fit together. The eGFR estimates how well your kidneys are filtering waste from your blood, based on a simple blood test for creatinine. A normal eGFR is above 90 mL/min, and values below 60 sustained over three months indicate chronic kidney disease.

The uACR and eGFR measure different aspects of kidney health. You can have a normal eGFR but an elevated uACR, which means the filtering barrier is damaged enough to leak protein but overall filtering capacity has not yet declined. You can also have a reduced eGFR with a normal uACR, though this combination is less common in conditions like diabetes. When doctors stage chronic kidney disease, they use both numbers together. A grid combining eGFR stages (G1 through G5) and albuminuria categories (A1 through A3) determines how urgently a patient needs referral to a nephrologist, how often monitoring should happen, and which treatments are appropriate.²

Someone with an eGFR of 55 and a uACR of 250 mg/g, for instance, faces substantially higher risks than someone with the same eGFR but a uACR of 15 mg/g. The albuminuria category shifts the risk profile upward at every level of eGFR. That is why checking only eGFR and ignoring the uACR can underestimate a person’s true kidney risk.

Microalbuminuria Versus Macroalbuminuria

Older medical literature and some lab reports still use the terms “microalbuminuria” and “macroalbuminuria.” Microalbuminuria referred to uACR values in the range of roughly 30 to 300 mg/g, while macroalbuminuria meant anything above 300 mg/g. The “micro” prefix never meant the albumin molecules were smaller; it simply indicated that the quantity was too small to be detected by standard urine dipstick tests and required a more sensitive assay.

Current guidelines have moved away from these terms in favor of “moderately increased albuminuria” (A2) and “severely increased albuminuria” (A3), partly because the old terminology confused patients and partly because the clinical relevance is about the degree of albumin leakage, not the detection method. You may still see “microalbumin” printed on your lab requisition or report, since labs update their terminology slowly. The numbers and their meaning are the same regardless of which label your lab uses.

Getting an Accurate Sample at Home or in the Lab

If your doctor hands you a specimen cup and asks for a first-morning void, a few practical steps help ensure the result reflects your actual kidney status rather than noise from avoidable sources. Collect the sample first thing after waking, before eating or drinking anything. Avoid strenuous exercise the day before. If you are sick with a fever or suspect a urinary tract infection, let your doctor know so the test can be rescheduled or the result can be interpreted in that context. Women who are menstruating should mention it, since blood contamination in the sample can elevate protein readings.

Hydration affects concentration but not the ratio as much as you might expect, because the creatinine denominator adjusts for dilution. Still, extreme dehydration or overhydration can push results to one end or the other in borderline cases. Drinking a normal amount of water the evening before and not chugging a liter right before collecting the sample is sensible advice.

If a random urine sample is collected at a clinic visit instead of a morning specimen, the result is still informative. A reading well below 30 mg/g on a random sample is reassuring. A reading well above 30 mg/g is worth flagging. Results hovering near the cutoff on a random sample are the ones most likely to benefit from a follow-up first-morning test.¹

When the Ratio Changes Over Time

For anyone tracking their uACR over months or years, the trend matters as much as any individual number. A ratio that starts at 45 mg/g and drops to 20 mg/g after starting a new blood pressure medication is an encouraging sign that the treatment is reducing kidney stress. A ratio that climbs from 50 to 150 mg/g over a year, despite treatment, tells a different story and often prompts a medication adjustment, tighter blood sugar or blood pressure targets, or a nephrology referral.

Research on people with type 2 diabetes and chronic kidney disease has shown that reductions in uACR over time are linked to lower rates of kidney failure, cardiovascular events, and death.⁵ This makes the ratio not just a diagnostic snapshot but a useful tracking tool. If you are being treated for kidney disease, asking your doctor to show you the trend across your last several lab results can be a motivating and informative exercise, more so than fixating on any single number.