Additional Blood Work Recommended for Elevated ACR
For patients with an elevated Albumin-to-Creatinine Ratio (ACR), comprehensive laboratory evaluation should include serum creatinine with eGFR calculation, complete metabolic panel, and confirmation of albuminuria with repeat ACR testing to assess kidney function and disease progression. 1
Confirmation of Elevated ACR
- First morning void urine samples should be used for ACR measurement to minimize variability 1
- Elevated ACR should be confirmed with 2 additional tests during the subsequent 3-6 months due to high day-to-day variability 1, 2
- Avoid testing during urinary tract infection, as this can cause false positive results 1
- Consider using the mean of multiple collections when monitoring changes in albuminuria over time 2
Essential Laboratory Tests
- Serum creatinine with eGFR calculation using the 2021 CKD-EPI equation without race variable 1
- Comprehensive metabolic panel to assess overall kidney function 1
- If eGFR is <60 mL/min/1.73 m² and/or albuminuria is >30 mg/g, repeat ACR testing every 6 months 1
- 12-lead ECG for all patients with elevated ACR, especially if hypertensive 1
Additional Testing Based on Clinical Context
- Consider cystatin C measurement in adults with eGFRcreat 45-59 mL/min/1.73 m² who don't have other markers of kidney damage to confirm CKD diagnosis 1
- For diabetic patients, HbA1c testing to assess glycemic control 1
- Lipid profile to assess cardiovascular risk, as elevated ACR increases cardiovascular mortality 3
- Echocardiography if ECG abnormalities or signs/symptoms of cardiac disease are present 1
- Fundoscopy for patients with diabetes or severe hypertension (BP >180/110 mmHg) 1
Monitoring Frequency
- For patients with moderately increased albuminuria (ACR 30-299 mg/g), monitor ACR and eGFR at least annually 1
- For patients with severely increased albuminuria (ACR >300 mg/g) or eGFR <45 mL/min/1.73 m², monitor twice yearly 1
- More frequent monitoring is warranted when there are changes in clinical status or when starting new medications like SGLT2 inhibitors, ACE inhibitors, or ARBs 1
Important Considerations
- High within-individual variability of ACR (coefficient of variation ~49%) means a single elevated result should be interpreted cautiously 2
- When using ACR instead of 24-hour urine albumin excretion, approximately 12% of patients may be reclassified to different albuminuria categories 4
- Consider nephrology referral when eGFR <45 mL/min/1.73 m² or if there is consistent finding of significant albuminuria (ACR >300 mg/g) 1
- Immediate nephrology referral is recommended once eGFR drops below 30 mL/min/1.73 m² 1