How to initiate lithium therapy in a patient post gastric surgery?

Lithium Initiation Protocol After Gastric Surgery

Patients who have undergone gastric surgery require significantly reduced lithium doses (typically 50-75% of standard dose) with more frequent monitoring to prevent lithium toxicity, which can lead to serious morbidity and mortality.

Pre-Initiation Assessment

• Verify type of gastric surgery performed (sleeve gastrectomy, Roux-en-Y, etc.)
• Assess baseline renal function (eGFR, creatinine)
• Check electrolytes, particularly sodium levels
• Evaluate hydration status and fluid balance
• Review all medications for potential interactions (especially diuretics, which are contraindicated)

Dosing Protocol

1. Starting dose:

   • Begin with 50% of the typical starting dose (e.g., 150-300 mg/day instead of 600 mg/day)
   • Use divided doses (twice daily) to minimize peak concentrations
   • Consider extended-release formulations to reduce absorption variability

2. Titration schedule:

   • Increase by no more than 150 mg every 7 days
   • Check lithium levels before each dose increase
   • Target serum lithium levels at the lower end of therapeutic range (0.6-0.8 mEq/L)

Monitoring Protocol

• Check lithium levels:

  • 5 days after initiation
  • 5 days after each dose adjustment
  • Weekly for the first month
  • Every 2 weeks for the second month
  • Monthly thereafter for 6 months
  • Then quarterly once stable

• Monitor renal function:

  • Baseline, then monthly for first 3 months
  • Every 3 months thereafter

Nutritional Considerations

• Ensure consistent sodium intake (sudden changes can affect lithium levels)
• Monitor for signs of dehydration (can precipitate toxicity)
• Ensure adequate protein intake (60-80 g/day for restrictive procedures; 90+ g/day for malabsorptive procedures) 1
• Consider thiamine supplementation to prevent deficiency, especially with early vomiting 1

Warning Signs of Toxicity

Instruct patients to immediately report:

• Persistent diarrhea
• Vomiting
• Tremor
• Drowsiness or confusion
• Muscle weakness
• Ataxia

Risk Factors for Lithium Toxicity Post-Gastric Surgery

Multiple case reports document lithium toxicity following various types of bariatric procedures, including sleeve gastrectomy 2, 3, 4 and Roux-en-Y gastric bypass 5. These cases highlight several important risk factors:

• Altered absorption kinetics
• Reduced gastric volume
• Changes in gastric pH
• Fluid/electrolyte imbalances
• Postoperative nausea/vomiting
• Use of proton pump inhibitors

Special Considerations

• Avoid diuretics: Lithium is contraindicated with diuretics due to extremely high risk of toxicity 6
• PPI use: Consider the impact of acid-suppressive therapy on lithium absorption, which may be prescribed post-surgery 1
• Dehydration risk: Patients may have difficulty maintaining adequate fluid intake post-surgery
• Medication timing: Administer lithium at least 2 hours apart from other medications to minimize interaction risks

Follow-up Care

• Regular psychiatric assessment for mood symptoms and medication efficacy
• Coordinate care between psychiatry and bariatric surgery teams
• Consider alternative mood stabilizers if lithium proves difficult to manage safely

By following this protocol, clinicians can minimize the risk of lithium toxicity while still providing effective treatment for bipolar disorder in patients who have undergone gastric surgery.