This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
A spot test instead of a 24-hour collection
Protein in the urine is one of the earliest signs of kidney damage. The classic test collects all urine for 24 hours, which is inconvenient and often incomplete. A single urine sample works almost as well if you divide the protein or albumin concentration by the creatinine concentration, because creatinine is excreted at a fairly steady rate.
The formulas
UPCR = urine protein ÷ urine creatinine
UACR = urine albumin ÷ urine creatinine
When both concentrations are in mg/dL, the ratio in mg/mg is roughly the excretion in grams per day, and the ratio × 1,000 gives mg/g. Many countries outside the United States report the ratio in mg/mmol; divide mg/g by 8.84 to convert.
Example
A urine sample with 30 mg/dL of protein and 100 mg/dL of creatinine:
UPCR = 30 ÷ 100 = 0.30 mg/mg = 300 mg/g, suggesting about 0.3 g of protein a day. That is mildly increased.
Reference values
| Test | Normal | Increased | Severe |
|---|---|---|---|
| UACR (KDIGO) | A1: below 30 mg/g | A2: 30 to 300 mg/g | A3: above 300 mg/g |
| UPCR | below 150 mg/g | 150 to 500 mg/g | above 500 mg/g |
Proteinuria of about 3,000 to 3,500 mg/g or more is called nephrotic range and is often accompanied by swelling and low blood albumin.
When it is used
- Diabetes and high blood pressure: an annual UACR detects early kidney disease, when treatment such as ACE inhibitors, ARBs and SGLT2 inhibitors can slow it down.
- Chronic kidney disease: KDIGO stages combine eGFR (G1 to G5) and albuminuria (A1 to A3) to estimate risk.
- Pregnancy: a UPCR of 0.3 mg/mg (30 mg/mmol) or more is a criterion for significant proteinuria in preeclampsia.
Pitfalls
The assumption of 1 g of creatinine a day works best for average adults. Very muscular people excrete more creatinine, which lowers the ratio; frail older adults and people with low muscle mass excrete less, which raises it. Exercise, fever, urinary infection and uncontrolled glucose can also raise results temporarily. Confirm an abnormal result on two of three samples over 3 to 6 months, preferably first-morning urine.