From the Guidelines
Elevated albumin-to-creatinine ratio (ACR) in urine is primarily caused by kidney damage, with the most common causes being diabetes mellitus and hypertension, as well as other factors such as glomerulonephritis, autoimmune diseases, and certain medications. The causes of elevated ACR can be categorized into permanent and temporary factors. Permanent factors include:
- Diabetes mellitus, where high blood sugar damages kidney filtration units 1
- Hypertension, which increases pressure in kidney blood vessels 1
- Glomerulonephritis (inflammation of kidney filtering units)
- Autoimmune diseases like lupus
- Urinary tract infections
- Heart failure
- Obesity
- Certain medications such as NSAIDs and some antibiotics
Temporary elevation can occur due to:
- Fever
- Strenuous exercise
- Dehydration
- Urinary tract infections
- Certain physiological states like pregnancy 1
It is essential to note that elevated ACR often indicates early kidney disease before symptoms appear, and regular monitoring is recommended for those with risk factors 1. Treatment typically focuses on managing the underlying condition through blood pressure control, blood sugar management, medication adjustments, and lifestyle modifications including reduced sodium intake, regular exercise, and maintaining healthy weight. According to the most recent guideline, a normal UACR is defined as <30 mg/g Cr, and high urinary albumin excretion is defined as ≥30 mg/g Cr 1.
From the Research
Causes of Elevated Albumin to Creatinine Ratio (ACR) in Urine
- Kidney cancer and nephrectomy: Patients with kidney cancer are at risk for chronic kidney disease after radical and partial nephrectomy, and the severity of albuminuria can stratify risk of progressive chronic kidney disease 2.
- Chronic kidney disease: Albuminuria is an important sign of chronic kidney disease, and the urine albumin-to-creatinine ratio is recommended for albuminuria screening 3, 4, 5.
- Cardiovascular risk factors: Participants who were reclassified to a higher ACR category had a worse cardiovascular risk profile compared with non-reclassified participants 3.
- Adiposity and insulin secretion and resistance: Quartiles of ACR were positively associated with markers of adiposity and insulin secretion and resistance 6.
- Blood pressure and antihypertensive agents: Quartiles of ACR were positively associated with blood pressure and use of antihypertensive agents with antiproteinuric effects 6.
- Muscle mass: Differences in spot urine creatinine values may lead to under- or overestimation of measured albumin excretion rate (mAER) by ACR in patients with extremes of muscle mass 5.
Factors Affecting ACR Measurements
- Urinary creatinine excretion: Interindividual differences in urinary creatinine excretion may affect ACR measurements 3.
- Spot urine collection: Early morning void urine collection instead of spot urine collection may affect ACR measurements 3.
- Point-of-care testing: The diagnostic accuracy of a urine albumin-creatinine ratio point-of-care test may be lower than laboratory-based measurements 4.