Additional Blood Work Needed for Elevated ACR
For patients with elevated Albumin-to-Creatinine Ratio (ACR), a comprehensive laboratory evaluation should include serum creatinine with eGFR calculation, complete metabolic panel, fasting blood glucose, HbA1c, lipid profile, and repeat ACR testing to confirm the initial finding. 1
Confirmation of Elevated ACR
- Repeat ACR testing is essential due to high day-to-day variability (up to 48.8% coefficient of variation) 2
- Collect 2-3 first morning urine samples over a 3-6 month period to confirm the elevation 1
- Ensure testing is performed when patient does not have:
- Urinary tract infection
- Fever
- Recent vigorous exercise (within 24 hours)
- Marked hyperglycemia
- Congestive heart failure exacerbation
- Menstruation (in females) 1
Essential Laboratory Tests
Kidney Function Assessment
- Serum creatinine with eGFR calculation using CKD-EPI equation 1
- Consider cystatin C measurement if:
- eGFR is 45-59 mL/min/1.73m² and no other markers of kidney damage are present
- Confirmation of CKD status is required 1
Metabolic Evaluation
- Complete blood count
- Comprehensive metabolic panel (including electrolytes, BUN)
- Fasting blood glucose
- HbA1c (especially important as diabetes is a common cause of albuminuria) 1
- Lipid profile (total cholesterol, LDL, HDL, triglycerides) 1
Additional Tests Based on Clinical Context
- Serum albumin (if nephrotic-range proteinuria is suspected)
- Urine sediment examination for casts, RBCs, WBCs
- Thyroid-stimulating hormone 1
- Serum uric acid (optional) 1
Frequency of Monitoring
The frequency of follow-up testing should be based on the severity of albuminuria and eGFR:
- For moderately increased albuminuria (ACR 30-299 mg/g) and eGFR ≥60 mL/min/1.73m²: Monitor ACR and eGFR annually 1
- For severely increased albuminuria (ACR ≥300 mg/g) or eGFR <60 mL/min/1.73m²: Monitor ACR and eGFR every 6 months 1
- For eGFR <45 mL/min/1.73m²: Consider referral to nephrology for co-management 1
Clinical Pearls and Pitfalls
- A single elevated ACR may not represent true kidney disease due to high biological variability - always confirm with repeat testing 2, 3
- For patients with ACR <30 mg/g, a change of >467% is needed to indicate a significant change in albuminuria status with 95% certainty 3
- For patients with ACR 30-300 mg/g, a change of >170% is required to indicate a significant change 3
- Even mildly elevated ACR (10-30 mg/g) is associated with increased cardiovascular mortality risk, especially in patients with diabetes 4
- Elevated ACR >63 mg/g is strongly associated with risk of developing renal tubular injury in patients with type 2 diabetes 5
- When initiating ACE inhibitors or ARBs, monitor serum creatinine and potassium levels for potential increases 1
Referral to Nephrology
Consider nephrology referral if:
- eGFR <30 mL/min/1.73m²
- Persistent ACR ≥300 mg/g despite appropriate therapy
- Rapid decline in eGFR (>5 mL/min/1.73m² per year)
- Uncertainty about the etiology of kidney disease
- Difficult management issues 1