Monitor the Albumin-to-Creatinine Ratio (16.2 mg/g)
The albumin-to-creatinine ratio is the single best value to monitor for assessing kidney function and cardiovascular risk in your patient. The individual components (microalbumin 19.3 mg/dL and creatinine 118.9 mg/dL) have no independent clinical significance—the ratio is what matters. 1, 2
Why the Ratio is Superior
The ratio corrects for urine concentration variability, which is why laboratories report albuminuria as milligrams of albumin per gram of creatinine rather than absolute values. 1
Your patient's ratio of 16.2 mg/g creatinine is normal (normal is defined as ≤30 mg/g creatinine), indicating no microalbuminuria at this time. 1
The elevated urine creatinine (118.9 mg/dL) is actually favorable—it simply indicates concentrated urine and makes the ratio more accurate by serving as an internal control. 2
Common Pitfall to Avoid
Do not confuse urine creatinine with serum creatinine. This is a critical distinction:
Urine creatinine on an albumin-to-creatinine ratio test is merely a normalizing factor for the albumin measurement and does not assess kidney function. 2
Serum creatinine reflects actual kidney function and is used to calculate estimated GFR (eGFR). 2
To properly assess kidney function, you must separately measure serum creatinine and calculate eGFR, which should be done annually in all patients with diabetes or hypertension. 2
Monitoring Strategy Going Forward
Screen annually with the albumin-to-creatinine ratio if your patient has diabetes, hypertension, or family history of chronic kidney disease. 1
Use first-morning void specimens for future testing, as they minimize effects of orthostatic proteinuria and provide the most concentrated, reliable samples due to known diurnal variation in albumin excretion. 1, 2
Confirm any abnormal result (ratio >30 mg/g) with 2 out of 3 specimens collected within 3-6 months before establishing a diagnosis, due to 40-50% day-to-day variability in albumin excretion. 1, 2
Factors That Can Falsely Elevate the Ratio
Before repeat testing if values become abnormal, ensure your patient avoids:
- Vigorous exercise within 24 hours before collection 1
- Acute infection or fever 1, 2
- Marked hyperglycemia 1, 2
- Congestive heart failure 2
- Urinary tract infection 1, 2
Clinical Significance of Monitoring
Microalbuminuria (30-299 mg/g) predicts cardiovascular morbidity and mortality independent of other risk factors and indicates generalized vascular dysfunction beyond just kidney involvement. 2, 3, 4
Early detection allows intervention with ACE inhibitors or ARBs, aggressive blood pressure control (target <130/80 mmHg), and glycemic control (HbA1c <7% in diabetics) to prevent progression to overt nephropathy. 3, 5
At any level of GFR, elevated albumin-to-creatinine ratio is associated with increased risk for cardiovascular disease, chronic kidney disease progression, and mortality. 6