What testing and side effects should be assessed in a patient returning for recheck 6 weeks after starting lisinopril (Angiotensin-Converting Enzyme (ACE) inhibitor)?

Monitoring and Side Effects Assessment for Patients on Lisinopril at 6-Week Follow-Up

At the 6-week follow-up visit for a patient on lisinopril, renal function tests and serum electrolytes should be checked, with particular attention to creatinine and potassium levels, while monitoring for common side effects including cough, hypotension, dizziness, and angioedema. 1

Laboratory Testing Required at 6-Week Follow-Up

The following tests should be performed:

• Renal function tests:

  • Serum creatinine (acceptable increase: up to 50% from baseline or to maximum of 265 μmol/L/3 mg/dL) 1
  • Blood urea nitrogen (BUN)

• Serum electrolytes:

  • Potassium (acceptable range: <5.5 mmol/L) 1
  • Sodium (to check for hyponatremia) 2

Side Effects to Assess

High Priority Side Effects

1. Renal dysfunction:

   • Assess for worsening renal function (creatinine increase >50% from baseline)
   • Minor increases in BUN and creatinine occur in approximately 2% of hypertensive patients 2
   • More common in patients on concomitant diuretics (11.6%) 2

2. Electrolyte abnormalities:

   • Hyperkalemia (occurs in 2.2-4.8% of patients) 2
   • Hyponatremia 2

3. Hypotension and related symptoms:

   • Symptomatic hypotension (dizziness, lightheadedness)
   • Orthostatic effects (check orthostatic blood pressure) 2
   • In heart failure patients, hypotension occurs in 7-11% 2

4. Respiratory symptoms:

   • Persistent dry cough (common ACE inhibitor side effect) 1
   • Angioedema (rare but serious) 1, 2

Additional Side Effects to Monitor

• Gastrointestinal: Diarrhea, pancreatitis, constipation, dry mouth 2
• Neurological: Headache, dizziness, fatigue, asthenia 2
• Metabolic: Hyperkalemia, gout 2
• Dermatological: Rash, urticaria, photosensitivity 2
• Hematologic: Rare bone marrow depression, anemia (small decreases in hemoglobin/hematocrit) 2

Management Algorithm Based on Findings

For Renal Function Abnormalities:

• If creatinine increases by >50% or exceeds 265 μmol/L (3 mg/dL):
  1. Check for nephrotoxic drugs (especially NSAIDs) 1
  2. Consider reducing lisinopril dose or discontinuing if necessary
  3. If creatinine >310 μmol/L (3.5 mg/dL), stop lisinopril immediately 1

For Electrolyte Abnormalities:

• If potassium >5.5 mmol/L:
  1. Reduce lisinopril dose by half
  2. Check for potassium supplements or potassium-sparing diuretics 1
  3. If potassium >6.0 mmol/L, stop lisinopril immediately 1

For Hypotension:

• If symptomatic hypotension present:
  1. Consider reducing diuretic dose if applicable
  2. Reassure patient that this often improves with time 1
  3. If severe, consider dose reduction

For Cough:

• If persistent dry cough develops:
  1. Assess severity and impact on quality of life
  2. If intolerable, consider switching to an ARB 1

Common Pitfalls and Caveats

1. Don't discontinue lisinopril for minor, expected increases in creatinine - Some increase in creatinine is expected and not clinically significant unless rapid and substantial 1

2. Don't overlook drug interactions - Check for concomitant use of:

   • NSAIDs (can worsen renal function) 1
   • Potassium-sparing diuretics (increase hyperkalemia risk) 1
   • Antidiabetic medications (increased hypoglycemia risk) 2

3. Don't miss the opportunity for dose titration - If no adverse effects are present, consider dose up-titration toward target dose (20-35 mg daily for lisinopril) 1

4. Don't ignore asymptomatic hypotension - While it doesn't require intervention, document it for future reference 1

5. Don't forget to schedule the next follow-up - After the 6-week check, if stable, plan for the next assessment at 3 months and then 6 months 1

Following this structured approach to monitoring will help ensure safe and effective use of lisinopril while minimizing risks associated with ACE inhibitor therapy.