Urine albumin-to-creatinine ratio mg/g to mg/mmol Converter

UACR in two units: the short answer

To convert the urine albumin-to-creatinine ratio (UACR, also called ACR) from mg/g to mg/mmol, multiply by 0.113 (or divide by 8.84). To convert mg/mmol back to mg/g, multiply by 8.84. A UACR of 30 mg/g is therefore 3.4 mg/mmol – usually rounded to the guideline threshold of 3 mg/mmol – and 30 mg/mmol is about 265 mg/g. The converter above handles both directions and shows the KDIGO albuminuria categories A1, A2 and A3.

UACR is one of the two key tests of kidney health, alongside eGFR, and the only one that detects kidney damage before kidney function falls. US laboratories usually report it in mg/g, while laboratories in the UK, Europe and Australia report mg/mmol. Because guideline categories are written as "30 mg/g" and "3 mg/mmol", which do not convert exactly, the rounding conventions are worth understanding. This guide covers the conversion, the categories, why UACR matters, and how to collect and interpret the test.

What UACR measures

Healthy kidneys keep almost all albumin – the most abundant blood protein – in the bloodstream, letting only tiny amounts into the urine. When the kidney's filters (glomeruli) are damaged, more albumin leaks through. This is called albuminuria (older terms: microalbuminuria and macroalbuminuria).

Measuring albumin alone in a random urine sample would be unreliable, because urine concentration varies with how much a person drinks. Dividing urine albumin by urine creatinine – which is excreted at a fairly steady rate – corrects for this, giving a ratio that closely approximates 24-hour albumin excretion. A UACR of 30 mg/g corresponds roughly to 30 mg of albumin excreted per day.

mg/g and mg/mmol explained

• mg/g – milligrams of albumin per gram of creatinine. Used in the United States and by KDIGO alongside the SI version.
• mg/mmol – milligrams of albumin per millimole of creatinine. Used in the UK, Europe, Australia and elsewhere.

Why the factor is 0.113

Creatinine has a molar mass of 113.12 g/mol, so 1 mmol of creatinine weighs 0.11312 g. A ratio of 1 mg albumin per gram of creatinine equals 1 mg per (1 ÷ 0.11312) mmol, which is 0.113 mg/mmol. Conversely, 1 mg/mmol = 8.84 mg/g.

Why "30 mg/g" and "3 mg/mmol" are treated as equivalent

Strictly, 30 mg/g converts to 3.39 mg/mmol, and 3 mg/mmol converts to 26.5 mg/g. KDIGO uses the rounded pairs 30 mg/g ≈ 3 mg/mmol and 300 mg/g ≈ 30 mg/mmol for simplicity, recognising that the test has substantial biological variability. So a result of 3.2 mg/mmol (28 mg/g) would be classified as A2 in a UK laboratory using 3 mg/mmol, but as A1 in a US laboratory using 30 mg/g. Results close to a threshold should always be repeated.

How to convert UACR step by step

1. Check the unit: mg/g or mg/mmol. Some laboratories report albumin-to-creatinine ratio in mg/mmol under the name "ACR".
2. For mg/g to mg/mmol, multiply by 0.113.
3. For mg/mmol to mg/g, multiply by 8.84.
4. Round to one decimal place for mg/mmol and whole numbers for mg/g.

Worked examples

• 10 mg/g × 0.113 = 1.1 mg/mmol – normal (A1).
• 30 mg/g × 0.113 = 3.4 mg/mmol – the A1/A2 boundary.
• 100 mg/g × 0.113 = 11.3 mg/mmol – moderately increased (A2).
• 300 mg/g × 0.113 = 33.9 mg/mmol – the A2/A3 boundary.
• 1,000 mg/g × 0.113 = 113 mg/mmol – severely increased (A3).
• 2.5 mg/mmol × 8.84 = 22 mg/g.
• 70 mg/mmol × 8.84 = 619 mg/g – a level relevant to referral thresholds in UK guidance.

UACR conversion chart

KDIGO albuminuria categories

Nephrotic-range proteinuria – heavy protein loss that causes low serum albumin and swelling – generally corresponds to a UACR above about 2,200 mg/g (220 mg/mmol), or a protein-to-creatinine ratio above about 3,000 mg/g (300 mg/mmol).

A note on "normal"

KDIGO's A1 category is labelled "normal to mildly increased" because risk rises progressively even within it. Studies show that cardiovascular and kidney risks begin to increase at UACR values of about 10 mg/g (1 mg/mmol), well below the 30 mg/g threshold. Young healthy adults typically have values below about 10 mg/g.

Why UACR matters

Diagnosing and staging chronic kidney disease

Chronic kidney disease (CKD) is defined as abnormalities of kidney structure or function present for more than three months. A UACR of 30 mg/g (3 mg/mmol) or more, persisting for three months, is enough to diagnose CKD even when eGFR is normal. KDIGO classifies CKD using both eGFR (G1–G5) and albuminuria (A1–A3), producing the well-known "heat map": a person with G3a and A3, for example, is at much higher risk than one with G3a and A1.

Predicting kidney and heart risk

Albuminuria is a strong, independent predictor of:

• progression to kidney failure
• heart attack, stroke and heart failure
• death from cardiovascular causes

Each increase in UACR category is associated with a substantial increase in risk at every level of eGFR.

Guiding treatment

UACR guides treatment decisions in diabetes and CKD:

• ACE inhibitors or angiotensin receptor blockers are recommended for people with diabetes and albuminuria, and for those with CKD and A2–A3 albuminuria, because they reduce albumin leakage and slow kidney decline.
• SGLT2 inhibitors (such as dapagliflozin and empagliflozin) reduce kidney failure and cardiovascular events in people with CKD, with the clearest benefit in those with albuminuria.
• Finerenone, a non-steroidal mineralocorticoid receptor antagonist, is recommended for people with type 2 diabetes, CKD and persistent albuminuria despite other treatment.
• GLP-1 receptor agonists, such as semaglutide, have shown kidney benefits in people with type 2 diabetes and CKD.

A fall in UACR of 30% or more after starting treatment is generally considered a good response.

The KDIGO risk "heat map"

KDIGO combines eGFR and albuminuria categories into a colour-coded grid that summarises the risk of kidney failure, cardiovascular events and death. A simplified version:

The grid also guides how often people should be monitored – from once a year in the lower-risk groups to four or more times a year in the highest-risk groups – and when specialist referral is appropriate.

Tracking UACR over time

Because day-to-day variation is large, trends over several results matter more than any single value. Changes are often expressed as percentages: KDIGO considers a fall of 30% or more a meaningful response to treatment, and a doubling a meaningful increase.

Example: a man with type 2 diabetes has a UACR of 210 mg/g in the US. He moves to the UK and starts an SGLT2 inhibitor, and a later result is 12 mg/mmol. Converted, 12 mg/mmol is 106 mg/g – a fall of about 50%, a good response, although he remains in category A2. Without conversion, the change from "210" to "12" might look dramatic, or it might be dismissed as a different test.

UACR in pregnancy

In pregnancy, proteinuria is assessed to help diagnose pre-eclampsia. Most guidelines use the protein-to-creatinine ratio, with a threshold of 30 mg/mmol (about 0.3 mg/mg, or 300 mg/g), but NICE also accepts a UACR of 8 mg/mmol or more (about 71 mg/g) as significant proteinuria in pregnancy. These thresholds are specific to pregnancy and differ from the CKD categories, so the unit and the context must both be checked.

UACR in children and young people

Albuminuria screening in children is mainly recommended for those with type 1 diabetes (typically starting at puberty or from age 10, after five years of diabetes) and type 2 diabetes (from diagnosis). Orthostatic (postural) proteinuria – protein in urine only after standing – is common in adolescents and is harmless, which is another reason first-morning samples are preferred. The same mg/g and mg/mmol thresholds are generally used.

Who should be tested

Guidelines recommend regular UACR testing for people at increased risk of kidney disease:

• Diabetes – at least once a year for everyone with type 2 diabetes from diagnosis, and for people with type 1 diabetes from five years after diagnosis (ADA Standards of Care).
• High blood pressure.
• Cardiovascular disease.
• Existing CKD – at least once a year, more often with higher risk.
• Family history of kidney failure or hereditary kidney disease.
• Other conditions – such as obesity, previous acute kidney injury, lupus or other systemic diseases affecting the kidneys.

How to collect a UACR sample

• An early-morning (first void) urine sample is preferred, because it gives the most consistent results and avoids the effect of standing and activity on albumin excretion. A random sample is acceptable for screening if a first-morning sample is not practical.
• Use a clean container; the laboratory needs only a small amount.
• Avoid testing during a urinary tract infection, a fever or menstruation, and within 24 hours of vigorous exercise.

Why repeat testing is needed

UACR can vary by 30–50% from day to day. KDIGO recommends confirming an abnormal result with repeat tests: two of three samples collected over three to six months should be abnormal before classifying a person as having persistent albuminuria.

What affects UACR results

Temporary increases in albuminuria can be caused by:

• vigorous exercise in the previous 24 hours
• urinary tract infection
• fever or acute illness
• very high blood pressure or uncontrolled high blood glucose
• heart failure decompensation
• menstruation (blood contamination)

The creatinine part of the ratio also matters. People with high muscle mass excrete more creatinine, which lowers the ratio; people with low muscle mass (such as older or frail people) excrete less, which raises it. Women typically have lower creatinine excretion than men, so their UACR is slightly higher for the same albumin excretion; some researchers have proposed sex-specific thresholds, but KDIGO uses the same categories for everyone.

UACR versus PCR and dipsticks

• Protein-to-creatinine ratio (PCR or UPCR) measures all proteins, not just albumin. It is sometimes used in non-diabetic kidney disease, in pregnancy (for pre-eclampsia) and when protein loss is heavy. A UPCR of 50 mg/mmol (about 440 mg/g) roughly corresponds to a UACR of 30 mg/mmol, but the relationship is not exact.
• Urine dipsticks detect protein only at higher concentrations (usually above about 300 mg/L) and miss moderately increased albuminuria. They are not recommended for screening people with diabetes.

Lifestyle measures that lower albuminuria

Alongside medicines, several everyday measures help reduce albumin leakage and protect the kidneys:

• Blood pressure control – most guidelines aim for a systolic pressure below about 120–130 mmHg in people with CKD and albuminuria, where tolerated.
• Blood glucose control in diabetes.
• Reducing salt intake – high salt intake blunts the effect of ACE inhibitors and ARBs on albuminuria. KDIGO suggests less than 2 g of sodium (about 5 g of salt) a day.
• Stopping smoking, which is associated with higher albuminuria and faster kidney decline.
• Weight loss in people with obesity.
• Avoiding very high protein intakes in people with CKD; KDIGO suggests about 0.8 g of protein per kg of body weight per day for adults with CKD G3–G5 not on dialysis.

Comparing UACR results across countries

When you have results from different countries, convert them all to one unit and classify each using the KDIGO categories. Remember that the boundaries differ slightly between units (30 mg/g versus 3 mg/mmol), so values close to a boundary – roughly 25–35 mg/g or 2.8–4.0 mg/mmol – may be classified differently by different laboratories. Repeat testing gives a clearer picture than debating a single borderline value.

When to see a doctor

See a doctor if your UACR is 30 mg/g (3 mg/mmol) or higher on repeat testing, if it is rising over time, or if you have diabetes, high blood pressure or heart disease and have never had a UACR test. In the UK, NICE recommends referral to a kidney specialist when the ACR is 70 mg/mmol (about 620 mg/g) or more, unless known to be caused by diabetes and already appropriately treated, and when ACR is 30 mg/mmol or more together with blood in the urine. Seek prompt care for new swelling of the legs or face, very foamy urine, or reduced urine output.