My glomerular filtration rate decreased from 106 to 69 mL/min/1.73 m² over five months and has now risen to 90 mL/min/1.73 m²; what steps should I take to manage this?

Management of Fluctuating GFR

Your GFR improvement from 69 to 90 mL/min/1.73 m² is reassuring, but the initial rapid decline from 106 to 69 over five months warrants investigation of the underlying cause and assessment of your albuminuria status to determine your CKD risk category and guide management.

Immediate Next Steps

1. Obtain Albuminuria Measurement

You need a urine albumin-to-creatinine ratio (ACR) test immediately. This is critical because your management pathway depends entirely on whether you have:

• Normal/mildly increased albuminuria (<3 mg/mmol or <30 mg/g)
• Moderately increased albuminuria (3-30 mg/mmol or 30-300 mg/g)
• Severely increased albuminuria (>30 mg/mmol or >300 mg/g)

Your current GFR of 90 mL/min/1.73 m² places you in the "normal/high or mildly decreased" category, but your risk stratification and treatment recommendations differ dramatically based on albuminuria 1.

2. Identify the Cause of Initial GFR Decline

The rapid drop from 106 to 69 over five months is concerning and requires explanation:

Review medications started during that period:

• ACE inhibitors, ARBs, SGLT2 inhibitors, or mineralocorticoid receptor antagonists can cause initial GFR declines of <30%, which are typically hemodynamic, reversible, and actually predict long-term kidney benefit 2, 3
• NSAIDs, certain antibiotics, or other nephrotoxic agents
• Diuretics causing volume depletion

Assess for acute kidney injury triggers:

• Dehydration episodes
• Infections or sepsis
• Contrast exposure
• Acute illnesses

Evaluate for underlying kidney disease:

• Diabetes status
• Hypertension control
• Autoimmune conditions
• Urinary obstruction

Risk Stratification Based on Current GFR (90 mL/min/1.73 m²)

Your management depends on your albuminuria level 1:

If albuminuria <3 mg/mmol: You are LOW RISK - routine monitoring is appropriate

If albuminuria 3-30 mg/mmol: You are MODERATE RISK - consider kidney-protective therapies

If albuminuria >30 mg/mmol: You are HIGH RISK - aggressive kidney-protective therapy is indicated

Medication Management Strategy

If You Have Albuminuria (≥3 mg/mmol):

Start SGLT2 inhibitor regardless of diabetes status - this is the cornerstone therapy for CKD protection 4, 1

Add ACE inhibitor or ARB if you have albuminuria and aren't already on one 4

Consider nonsteroidal MRA (finerenone) if:

• You have type 2 diabetes
• Albuminuria persists despite maximum tolerated ACE inhibitor/ARB
• Potassium ≤4.8 mmol/L
• Current GFR >25 mL/min/1.73 m² 4

Critical Caveat About Initial GFR Decline with These Medications:

Do not stop these medications if GFR drops <30% after initiation - this is expected, hemodynamic, usually reversible, and actually predicts greater long-term kidney benefit 4, 2, 3. The initial decline reflects beneficial reduction in glomerular hypertension and hyperfiltration, not kidney damage.

Monitoring Plan

Recheck GFR and electrolytes:

• 1-2 weeks after starting any new kidney-protective medication
• Then every 3-4 months once stable 4

Monitor potassium closely if on ACE inhibitor/ARB or MRA:

• At 1 month after initiation
• Every 4 months thereafter
• Hold MRA if potassium >5.5 mmol/L 4

Annual albuminuria monitoring to track progression and treatment response 4

Blood Pressure Target

Maintain blood pressure ≤130/80 mmHg - this is the target for all patients with CKD 5

Common Pitfalls to Avoid

1. Don't panic about initial GFR drops with SGLT2 inhibitors or RAS inhibitors - declines <30% are expected and beneficial 4, 2

2. Don't delay treatment waiting for "more decline" - your nadir of 69 already demonstrated vulnerability; protection should start now if you have albuminuria

3. Don't use age-adjusted GFR thresholds - GFR <60 mL/min/1.73 m² is abnormal at any age 6, 5

4. Don't forget to inform your pharmacist of your GFR when GFR <50 mL/min/1.73 m² for medication dosing adjustments 5

What Likely Happened

Your GFR recovery from 69 to 90 suggests the initial decline may have been:

• Acute kidney injury that resolved
• Medication-induced hemodynamic change that stabilized
• Volume depletion that was corrected
• Measurement variability (though a 37-point swing is substantial)

The key now is preventing future decline through appropriate risk stratification based on albuminuria and implementing kidney-protective therapies if indicated.