C. An ACR sample is collected over 24 hours – Explanation
Chronic kidney disease: proteinuria
Proteinuria is an important marker of chronic kidney disease, especially for diabetic nephropathy.
NICE recommend using the albumin:creatinine ratio (ACR) in preference to the protein:creatinine
ratio (PCR) when identifying patients with proteinuria as it has greater sensitivity. For quantification
and monitoring of proteinuria,
PCR can be used as an alternative, although ACR is recommended in diabetics. Urine reagent strips
are not recommended unless they express the result as an ACR
Approximate equivalent values
| ACR (mg/mmol) | PCR (mg/mmol) | Urinary protein excretion (g/24 h) |
| 30 | 50 | 0.5 |
| 70 | 100 | 1 |
Collecting an ACR sample
- by collecting a ‘spot’ sample it avoids the need to collect urine over a 24 hour period in order to
detect or quantify proteinuria - should be a first-pass morning urine specimen
- if the initial ACR is greater than 30 mg/mmol and less than 70 mg/mmol, confirm by a subsequent
early morning sample. If the initial ACR is greater than 70 mg/mmol a repeat sample need not be
tested Interpreting the ACR results - in non-diabetics an ACR greater than 30 mg/mmol is considered clinically significant proteinuria
- in diabetics microalbuminuria (ACR greater than 2.5 mg/mmol in men and ACR greater than 3.5
mg/mmol in women) is considered clinically significant
