From the Guidelines
Elevated albumin-to-creatinine ratio (ACR) should be confirmed through repeat testing, ideally with a first-morning urine sample, and initial evaluation should include a comprehensive history and physical examination, focusing on risk factors like diabetes, hypertension, and family history of kidney disease. The most recent and highest quality study, 1, recommends that screening for microalbuminuria can be performed by measuring the albumin-to-creatinine ratio in a random, spot collection, and that two of three specimens collected within a 3- to 6-month period should be abnormal before considering a patient to have crossed one of the diagnostic thresholds.
Initial Evaluation
Initial evaluation should include:
- Comprehensive history and physical examination
- Laboratory tests:
- Complete metabolic panel
- Complete blood count
- Urinalysis with microscopy
- Urine protein electrophoresis
- Serum protein electrophoresis
- Additional testing may include:
- Fasting glucose
- HbA1c
- Lipid panel
- Hepatitis B and C serologies
- Imaging studies:
- Renal ultrasound to assess kidney size, structure, and rule out obstruction
Referral to Nephrologist
Referral to a nephrologist is recommended for:
- Persistent albuminuria (ACR >30 mg/g for over 3 months) despite optimal management of underlying conditions
- ACR exceeds 300 mg/g, indicating significant proteinuria
- Rapidly declining kidney function
- Nephrotic-range proteinuria
- Systemic diseases affecting the kidneys are suspected
Treatment
Treatment focuses on managing underlying conditions with medications like:
- ACE inhibitors (e.g., lisinopril 10-40 mg daily)
- ARBs (e.g., losartan 50-100 mg daily) These medications reduce proteinuria and slow kidney disease progression by decreasing intraglomerular pressure. According to 1, ACE inhibitors or ARBs are recommended if systolic blood pressure is greater than 120 mmHg, CKD is present, and moderately to severely increased albuminuria is observed.
From the Research
Elevated ACR Workup
Elevated Albumin-to-Creatinine Ratio (ACR) is a significant indicator of kidney damage and renal function decline. The following points highlight the importance of ACR workup:
- High ACR levels are associated with an increased risk of renal tubular impairment in patients with type 2 diabetes 2.
- The risk of developing tubular injury increases with higher baseline ACR values and lower baseline estimated glomerular filtration rate (eGFR) 2.
- Patients with baseline ACR > 63.10 mg/g have a strong risk of developing renal tubular injury, with an odds ratio of 11.12 (P = 0.001) 2.
Relationship between ACR and Renal Outcomes
The relationship between ACR and renal outcomes is well-established:
- Lower eGFRs and higher urinary albumin-creatinine ratios are associated with an increased risk of long-term dialysis and doubling of serum creatinine level 3.
- Angiotensin II receptor blockers (ARBs) reduce the risk of end-stage renal disease (ESRD) by 23% in patients with diabetes and albuminuria, while angiotensin-converting enzyme (ACE) inhibitors reduce the risk of doubling of the serum creatinine level 4.
Management of Elevated ACR
The management of elevated ACR involves the use of renin-angiotensin-aldosterone system (RAAS) blockers:
- Reporting of estimated glomerular filtration rate (eGFR) is associated with an increased use of RAAS blockers in patients with chronic kidney disease (CKD) 5.
- Despite guideline recommendations, ARBs and ACE inhibitors are insufficiently prescribed for patients with hypertension associated with CKD and proteinuria, with a prescription rate of only 28% 6.