What is the approach to managing a patient with impaired renal function (elevated creatinine and decreased estimated Glomerular Filtration Rate (eGFR)) and urinary frequency?

Management of Elevated Creatinine, eGFR 57, and Urinary Frequency

For a patient with impaired renal function (elevated creatinine, eGFR 57) and urinary frequency, a comprehensive evaluation of kidney function and urinary symptoms is essential, with treatment focused on addressing underlying causes and preventing further kidney damage.

Initial Assessment and Diagnosis

• Confirm chronic kidney disease (CKD) diagnosis by repeating serum creatinine measurement and eGFR calculation after 3 months to establish persistence of abnormalities 1
• Assess urinary albumin-to-creatinine ratio (UACR) to determine albuminuria status, which is crucial for CKD staging and risk stratification 1
• Consider potential causes of elevated creatinine that may not reflect true kidney function impairment:
  • Medications that inhibit tubular creatinine secretion (e.g., certain antibiotics) 1, 2
  • High muscle mass or use of creatine supplements 3, 4
  • Dietary factors such as high protein intake or creatine supplements 3, 4

Evaluation of Urinary Frequency

• Determine if urinary frequency is related to:
  • Overactive bladder (OAB) symptoms 5
  • Urinary tract infection 1
  • Diabetes-related polyuria 1
  • Medication side effects 1
  • Benign prostatic hyperplasia (in males) 1

Management Approach Based on CKD Stage

For CKD Stage 3a (eGFR 45-59 mL/min/1.73m²)

• Optimize blood pressure control to reduce risk of CKD progression 1

  • Target BP ≤140/90 mmHg if UACR <30 mg/g 1
  • Target BP ≤130/80 mmHg if UACR ≥30 mg/g 1

• Medication management:

  • Use ACE inhibitors or ARBs if albuminuria is present (UACR ≥30 mg/g) 1
  • Consider SGLT2 inhibitors for patients with diabetes and CKD for cardiovascular risk reduction and to slow CKD progression 1
  • Adjust medication dosages based on eGFR level 5

• For urinary frequency management:

  • If diagnosed with overactive bladder, consider mirabegron starting at 25 mg daily (with dose adjustment based on renal function) 5
  • For eGFR 30-89 mL/min/1.73m², mirabegron can be titrated up to 50 mg daily if needed 5

Dietary Recommendations

• Recommend protein intake of approximately 0.8 g/kg body weight per day 1
• Sodium restriction and healthy diet adhering to medical nutrition therapy guidelines 1

Monitoring and Follow-up

• Monitor kidney function every 6 months for CKD Stage 3a with moderate albuminuria (UACR 30-300 mg/g) 1
• Consider using cystatin C-based eGFR (eGFRcr-cys) for more accurate assessment of kidney function, especially if creatinine-based eGFR may be inaccurate due to non-GFR determinants 1, 6
• Periodically monitor serum creatinine and potassium levels when using ACE inhibitors, ARBs, or diuretics 1

Referral to Specialist

• Refer to a nephrologist if:
  • eGFR continues to decline or falls below 30 mL/min/1.73m² 1
  • Urinary albumin levels continuously increase 1
  • Uncertainty about the etiology of CKD exists 1
  • Severe, disabling symptoms related to kidney dysfunction are present 1

Important Considerations

• Be aware that small fluctuations in GFR are common and do not necessarily indicate progression 1
• Consider that urinary frequency may be an early symptom of worsening kidney function or a separate urological issue 5
• Recognize that some medications can cause pseudo-worsening of kidney function by affecting creatinine secretion without actually impairing GFR 2

By following this structured approach, you can effectively manage a patient with elevated creatinine, reduced eGFR, and urinary frequency while preventing further kidney damage and addressing symptomatic concerns.