What blood work should be monitored for a patient with recent open heart surgery, triple bypass, taking pantoprazole, Eloquis (apixaban), Farxiga (dapagliflozin), Lipitor (atorvastatin), bumetanide, metoprolol, and digoxin?

Blood Work Monitoring for Post-Cardiac Surgery Patient on Multiple Medications

Regular monitoring of digoxin levels, renal function, electrolytes, and coagulation parameters is essential for this patient with recent triple bypass surgery taking multiple medications that can affect these parameters.

Digoxin Monitoring

• Digoxin level should be monitored regularly, as it has a narrow therapeutic window and is affected by several medications the patient is taking 1
• Initial digoxin level should be checked within 1-2 weeks of starting therapy or any dose adjustment 1
• Subsequent monitoring should occur at least every 3-6 months if stable, or more frequently with any changes in renal function or medication regimen 1, 2

Renal Function Monitoring

• Serum creatinine and eGFR should be monitored regularly due to:
  • Potential effects of digoxin (which is primarily eliminated by the kidneys) 2
  • Dapagliflozin (Farxiga) causes initial small increases in serum creatinine and decreases in eGFR within two weeks of starting therapy 3
  • Bumetanide can affect renal function and electrolyte balance 1
• Recommended frequency: Baseline, 2 weeks after starting therapy, and then every 3 months 3

Electrolyte Monitoring

• Serum potassium, sodium, magnesium, and calcium levels should be monitored regularly:
  • Hypokalemia increases risk of digoxin toxicity 1
  • Bumetanide (loop diuretic) can cause electrolyte depletion 1
  • Dapagliflozin can affect electrolyte balance 3
• Recommended frequency: Baseline, 2 weeks after starting therapy, and then every 3 months 1, 3
• Target potassium level should be maintained at ≥4.0 mEq/L to reduce risk of arrhythmias 1

Coagulation Parameters

• INR and PT should be monitored regularly for patients on apixaban (Eliquis) 1, 4
• Although apixaban doesn't require routine INR monitoring like warfarin, baseline coagulation parameters are important in this post-surgical patient 1, 4
• CBC with platelet count should be monitored due to risk of bleeding with apixaban 4
• Recommended frequency: Baseline and then every 3-6 months 1

Lipid Profile

• Lipid profile (total cholesterol, LDL, HDL, triglycerides) should be monitored for patients on atorvastatin (Lipitor) 1
• Dapagliflozin may cause small increases in LDL cholesterol 3
• Recommended frequency: Baseline and then every 6-12 months 1

Liver Function Tests

• Liver function tests (ALT, AST, bilirubin) should be monitored due to:
  • Atorvastatin (Lipitor) metabolism in the liver 1
  • Potential hepatic effects of multiple medications 1
• Recommended frequency: Baseline, 3 months after starting therapy, and then annually if stable 1

Blood Glucose Monitoring

• Blood glucose and HbA1c should be monitored regularly due to:
  • Dapagliflozin (Farxiga) is an SGLT2 inhibitor used for diabetes management 3
  • Risk of diabetic ketoacidosis with dapagliflozin 3
• Recommended frequency: Blood glucose as clinically indicated; HbA1c every 3-6 months 3

Hematocrit/Hemoglobin

• Complete blood count should be monitored due to:
  • Recent cardiac surgery and risk of anemia 1
  • Dapagliflozin can increase hematocrit values 3
  • Risk of bleeding with apixaban 4
• Recommended frequency: Baseline, 1 month post-surgery, and then every 3-6 months 1

Special Considerations

• Drug interactions require careful monitoring:
  • Digoxin levels may be affected by several medications in this regimen 1
  • Pantoprazole has been shown not to interact significantly with digoxin or metoprolol 5, 6
  • Apixaban pharmacokinetics generally remain stable even with weight changes 7
• Serum bicarbonate should be monitored due to potential decreases with dapagliflozin 3

Monitoring Schedule Summary

• Weekly: None required after initial post-surgical period
• Monthly: Digoxin level (initially, then less frequently when stable)
• Every 3 months: Renal function, electrolytes, CBC, HbA1c
• Every 6-12 months: Lipid profile, liver function tests