What is the next best step in managing a 38-year-old woman with mildly elevated serum creatinine (1.02 mg/dL), estimated glomerular filtration rate ~72 mL/min/1.73 m² (stage 2 chronic kidney disease), normal urine microalbumin‑to‑creatinine ratio, normal blood urea nitrogen, and normal complete blood count?

Management of Mildly Reduced eGFR in a 38-Year-Old Woman

Repeat the serum creatinine and eGFR measurement in 3 months to confirm chronicity, while simultaneously evaluating for underlying causes and cardiovascular risk factors. 1

Initial Assessment and Confirmation

This patient's presentation requires careful interpretation before labeling as chronic kidney disease:

• A single creatinine of 1.02 mg/dL with eGFR 72 mL/min/1.73 m² does NOT establish CKD. 1 CKD requires persistent abnormalities for ≥3 months, defined as either eGFR <60 mL/min/1.73 m² OR evidence of kidney damage (such as albuminuria ≥30 mg/g). 1, 2

• This patient has eGFR >60 mL/min/1.73 m² AND normal microalbumin-to-creatinine ratio, therefore she does NOT currently meet criteria for CKD. 1 Stage 1-2 CKD requires both eGFR ≥60 AND evidence of kidney damage (usually albuminuria). 1

• Repeat measurements are essential because biological variability in both creatinine and urinary albumin excretion is substantial (>20% variation). 1 Two of three specimens collected within 3-6 months should be abnormal before confirming albuminuria. 1

Diagnostic Workup During Observation Period

While awaiting confirmatory testing, evaluate for:

Causes of Kidney Injury

• Diabetes screening (hemoglobin A1c, fasting glucose) since diabetic kidney disease occurs in 20-40% of patients with diabetes and may be present at type 2 diabetes diagnosis. 1
• Blood pressure measurement at every visit, as hypertension is a leading cause of CKD in developed countries. 2
• Medication review for nephrotoxins, particularly NSAIDs, which can cause kidney injury. 1
• Urinalysis with microscopy to evaluate for hematuria, pyuria, or other sediment abnormalities suggesting glomerular disease. 1

Cardiovascular Risk Assessment

• Lipid panel (total cholesterol, LDL, HDL, triglycerides) since even mild reductions in kidney function increase cardiovascular risk. 1, 2

Management Strategy Based on Confirmatory Testing

If Repeat Testing Shows Persistent eGFR 60-89 mL/min/1.73 m² WITHOUT Albuminuria:

No specific CKD-directed therapy is indicated. 1 According to American Diabetes Association guidelines, ACE inhibitors or ARBs are NOT recommended for primary prevention in patients with normal blood pressure, normal urinary albumin-to-creatinine ratio (<30 mg/g), and normal eGFR. 1

Focus on:

• Identifying and treating underlying causes (diabetes, hypertension). 1
• Cardiovascular risk factor modification. 2
• Annual monitoring of kidney function and albuminuria. 1

If Albuminuria Develops (≥30 mg/g):

This would establish Stage 2 CKD (eGFR 60-89 with kidney damage). 1

Treatment priorities:

• ACE inhibitor or ARB therapy is recommended for modestly elevated albuminuria (30-299 mg/g) in patients with hypertension. 1
• Monitor serum creatinine and potassium periodically when using ACE inhibitors, ARBs, or diuretics. 1
• Do not discontinue renin-angiotensin system blockade for minor creatinine increases (≤30%) in the absence of volume depletion. 1

If eGFR Declines to <60 mL/min/1.73 m²:

This would establish Stage 3 CKD. 1

Additional interventions:

• Evaluate and manage CKD complications including anemia, bone mineral disease, metabolic acidosis. 1, 2
• Adjust medication dosing for renally cleared drugs. 2
• Dietary protein restriction to maximum 0.8 g/kg/day for stage 3 or higher CKD. 1

Critical Pitfalls to Avoid

• Do not diagnose CKD based on a single measurement. 1 Biological variability and transient factors (exercise, infection, fever, dehydration) can temporarily elevate creatinine or albuminuria. 1

• Do not initiate ACE inhibitor/ARB therapy solely for "renal protection" in patients with normal blood pressure and no albuminuria. 1 This is explicitly not recommended by guidelines.

• Recognize that creatinine of 1.02 mg/dL may be "normal" for this patient depending on age, sex, and muscle mass. 3 In a 38-year-old woman, this level warrants monitoring but not immediate intervention without confirmatory abnormalities.

• Consider non-diabetic causes if CKD is confirmed, particularly in a young patient without diabetes duration of 10+ years. 1 Prompt nephrology referral is warranted for uncertainty about etiology. 1