From the Guidelines
Elevated albumin-to-creatinine ratio (ACR) and protein in the urine indicate kidney damage and require prompt medical attention with treatment targeting blood pressure control and reduction of proteinuria. The condition often requires treatment with medications like angiotensin-converting enzyme (ACE) inhibitors (such as lisinopril 10-40 mg daily) or angiotensin receptor blockers (ARBs) like losartan 50-100 mg daily, which reduce protein leakage and protect kidney function 1.
Key Considerations
- Blood pressure control is essential, with a target below 130/80 mmHg, as hypertension can exacerbate kidney damage and proteinuria 1.
- Lifestyle modifications are also important, including:
- Reducing sodium intake to less than 2,300 mg daily
- Moderating protein consumption
- Maintaining a healthy weight
- Exercising regularly
- Avoiding nephrotoxic medications like NSAIDs
- Regular monitoring with urine tests and kidney function blood work every 3-6 months is necessary to track progress and adjust treatment as needed 1.
Proteinuria and Kidney Damage
Proteinuria occurs when the kidney's filtration barrier is damaged, allowing proteins like albumin to leak into the urine instead of remaining in the bloodstream. This damage can result from conditions such as diabetes, hypertension, glomerulonephritis, or other kidney diseases. Early intervention is crucial as persistent proteinuria can lead to progressive kidney function decline if left untreated 1.
Diagnosis and Management
The diagnosis of proteinuria and kidney damage involves measuring the albumin-to-creatinine ratio (ACR) in a laboratory setting, rather than relying on dipstick testing, which is less sensitive and specific 1. A normal UACR is defined as <30 mg/g Cr, and high urinary albumin excretion is defined as ≥30 mg/g Cr 1. However, UACR is a continuous measurement, and differences within the normal and abnormal ranges are associated with renal and cardiovascular outcomes 1.
Treatment and Outcomes
Treatment with ACE inhibitors or ARBs can reduce proteinuria and slow the progression of kidney disease, and is recommended as the primary treatment for children with ADPKD who have proteinuria 1. Reduction of proteinuria using ACE inhibitors or ARBs is associated with significant improvement in renal survival in patients with CKD 1. Prompt referral to a nephrologist is recommended for uncertainty about the etiology of kidney disease, difficult management issues, and rapidly progressing kidney disease 1.
From the FDA Drug Label
The RENAAL study was a randomized, placebo-controlled, double-blind, multicenter study conducted worldwide in 1513 patients with type 2 diabetes with nephropathy (defined as serum creatinine 1.3 to 3.0 mg/dL in females or males ≤60 kg and 1.5 to 3. 0 mg/dL in males >60 kg and proteinuria [urinary albumin to creatinine ratio ≥300 mg/g]) Compared with placebo, losartan significantly reduced proteinuria by an average of 34%, an effect that was evident within 3 months of starting therapy
Elevated ACR and protein in the urine can be treated with losartan, as it has been shown to:
- Reduce proteinuria by an average of 34%
- Slow the progression of nephropathy in patients with type 2 diabetes and a history of hypertension
- Decrease the risk of doubling of serum creatinine or end-stage renal disease (need for dialysis or renal transplantation) 2
From the Research
Elevated ACR and Protein in the Urine
Elevated Albumin-to-Creatinine Ratio (ACR) and protein in the urine are indicators of kidney damage or disease. The following points summarize the key findings related to elevated ACR and protein in the urine:
- Elevated ACR is a strong predictor of kidney disease progression and cardio-renal outcomes in patients with type 2 diabetes mellitus and kidney disease 3.
- ACR, protein-to-creatinine ratio (PCR), and 24-h urine protein excretion are correlated and can be used to monitor protein excretion in chronic kidney disease (CKD) patients 4, 5.
- The association between ACR and PCR is greater in patients with dipstick protein positive, urine creatinine level ≥ 60 mg/dl, and estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2 5.
- ACR is a better predictor of prognosis in IgA nephropathy compared to PCR and 24-h urine protein excretion 4.
- The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is recommended for estimating GFR, and ACR is recommended for assessing albuminuria 6, 7.
Factors Affecting ACR and Protein Measurements
Several factors can affect ACR and protein measurements, including:
- Muscle mass: Low muscle mass can imply borderline elevation in ACR due to low urinary creatinine, while high muscle mass can imply normal ACR even in the presence of high urinary albumin 6.
- Diet: Extremes of diet can affect serum creatinine and creatinine excretion, leading to inaccurate GFR estimates 7.
- Urine creatinine concentration: Low urinary creatinine concentration can affect the correlation between ACR and PCR 5.
Clinical Significance
Elevated ACR and protein in the urine are associated with an increased risk of kidney disease progression, cardio-renal outcomes, and mortality 3. Accurate measurement and interpretation of ACR and protein are crucial for early detection and management of kidney disease. The use of standardized equations, such as the CKD-EPI equation, and careful consideration of factors affecting ACR and protein measurements can help improve the accuracy of kidney function assessments 6, 7.