What are the symptoms and management of decreased estimated Glomerular Filtration Rate (eGFR) indicating impaired renal function?

Symptoms of Decreased eGFR

Decreased estimated Glomerular Filtration Rate (eGFR) often remains clinically asymptomatic until advanced stages of kidney dysfunction, with symptoms typically appearing when eGFR falls below 30 mL/min/1.73 m².

Symptoms Based on CKD Stages

Early CKD (eGFR 60-89 mL/min/1.73 m²)

• Generally asymptomatic
• May have no detectable clinical manifestations
• Diagnosis often made incidentally through laboratory testing

Moderate CKD (eGFR 30-59 mL/min/1.73 m²)

• Often still asymptomatic or with minimal symptoms
• Early complications may begin to develop:
  • Mild anemia
  • Early bone mineral disorders
  • Subtle electrolyte imbalances
  • Mild hypertension

Severe CKD (eGFR 15-29 mL/min/1.73 m²)

• More pronounced symptoms begin to emerge:
  • Fatigue and weakness
  • Poor appetite
  • Sleep disturbances
  • Difficulty concentrating
  • Peripheral edema
  • Hypertension
  • Metabolic acidosis

End-Stage Kidney Disease (eGFR <15 mL/min/1.73 m²)

• Most symptomatic stage with multiple manifestations 1:
  • Nausea and vomiting
  • Pruritus (itching)
  • Peripheral edema
  • Hyperpigmentation
  • Peripheral neuropathy
  • Severe anemia
  • Uremic encephalopathy (confusion, seizures)
  • Pericarditis
  • Uremic frost

Common Complications of Decreased eGFR

According to guidelines, the following complications become prevalent when eGFR falls below 60 mL/min/1.73 m² and worsen as CKD progresses 2:

1. Blood pressure abnormalities

   • Hypertension (>130/80 mmHg)
   • Volume overload

2. Electrolyte disturbances

   • Hyperkalemia (especially with ACE inhibitors/ARBs)
   • Hyperphosphatemia
   • Hypocalcemia

3. Metabolic abnormalities

   • Metabolic acidosis
   • Dyslipidemia

4. Hematologic issues

   • Anemia (due to decreased erythropoietin production)
   • Bleeding tendency

5. Bone disorders

   • Secondary hyperparathyroidism
   • Vitamin D deficiency
   • Renal osteodystrophy

Management of Decreased eGFR

Monitoring and Evaluation

1. Regular assessment of kidney function

   • Monitor eGFR and albuminuria at least annually 2
   • More frequent monitoring for eGFR <60 mL/min/1.73 m² 2:
     • Every 6-12 months for stage 3 CKD
     • Every 3-5 months for stage 4 CKD
     • Every 1-3 months for stage 5 CKD

2. Complication screening

   • Blood pressure at every visit
   • Electrolytes, calcium, phosphate, PTH, vitamin D
   • Hemoglobin and iron studies
   • Urinary albumin-to-creatinine ratio (UACR)

Medication Management

1. Blood pressure control

   • Target <130/80 mmHg 3
   • ACE inhibitors or ARBs preferred for patients with:
     • Albuminuria >300 mg/g 2
     • eGFR <60 mL/min/1.73 m² 2

2. Medication adjustments

   • Avoid nephrotoxic medications (NSAIDs)
   • Adjust medication dosages based on eGFR 2
   • Monitor for drug interactions:
     • Risk of hyperkalemia with ACE inhibitors/ARBs 4, 5
     • Avoid dual RAS blockade 4

3. Glycemic control in diabetic patients

   • Well-controlled blood glucose delays progression 2
   • Medication selection based on eGFR:
     • Metformin contraindicated when eGFR <30 mL/min/1.73 m² 3
     • SGLT2 inhibitors beneficial for eGFR ≥20 mL/min/1.73 m² 3
     • GLP-1 receptor agonists can be used with eGFR as low as 15 mL/min/1.73 m² 3

Dietary Modifications

1. Protein intake

   • Approximately 0.8 g/kg/day for patients with diabetic kidney disease 2, 3
   • May need to be higher in patients on dialysis 2

2. Sodium restriction

   • <2 g/day to improve BP control 3

3. Potassium restriction

   • Individualized based on serum potassium levels 2
   • More important with reduced eGFR and use of RAS blockers

Renal Replacement Therapy

1. Preparation and referral

   • Consider renal replacement therapy when eGFR <30 mL/min/1.73 m² 2, 3
   • Dialysis therapy and transplantation should be considered in patients with eGFR <30 mL/min/1.73 m² 2

2. Options discussion

   • Hemodialysis
   • Peritoneal dialysis
   • Kidney transplantation

Special Considerations

1. Acute Kidney Injury (AKI) prevention

   • Higher risk in patients with diabetes 2
   • Avoid nephrotoxic medications during acute illness
   • Temporary discontinuation of RAS blockade during acute illness may be necessary 3

2. Cardiovascular risk management

   • CKD is associated with increased cardiovascular risk 6, 7
   • Aggressive management of cardiovascular risk factors

3. Medication pitfalls

   • Don't discontinue ACE inhibitors/ARBs prematurely due to initial 10-20% increase in serum creatinine 3
   • Monitor for hyperkalemia with RAS blockers, especially in elderly patients 3
   • Avoid NSAIDs in all CKD patients 3

By systematically addressing these aspects of care, patients with decreased eGFR can experience improved outcomes and quality of life despite their kidney dysfunction.