Laboratory Monitoring for Patients on Sertraline and Trazodone
Baseline and periodic liver function tests, complete blood count, and electrolytes should be monitored in patients taking sertraline and trazodone, with special attention to signs of serotonin syndrome when these medications are used together. 1, 2
Initial Baseline Laboratory Tests
Before starting sertraline and trazodone therapy, the following baseline laboratory tests should be obtained:
- Complete blood count (CBC)
- Liver function tests (LFTs): ALT, AST, GGT, ALP, bilirubin
- Electrolytes, BUN, and creatinine
- Fasting glucose/HbA1c
- Lipid profile
- ECG (especially for patients with cardiac risk factors)
Ongoing Monitoring Schedule
Liver Function Tests
- Monitor LFTs at baseline, after 4 weeks of treatment, at 3 months, and then annually 1
- More frequent monitoring may be necessary for patients with pre-existing liver disease or abnormal baseline values
- Discontinue medications if ALT/AST elevations exceed 3-4 times the upper limit of normal 3, 4
Complete Blood Count
- Monitor CBC at baseline and then annually
- More frequent monitoring may be warranted in elderly patients or those with hematologic risk factors
Renal Function
- Monitor BUN and creatinine at baseline and annually
- More frequent monitoring in patients with renal impairment or elderly patients
Electrolytes
- Monitor sodium levels at baseline and periodically, especially in elderly patients
- Hyponatremia is a potential adverse effect of SSRIs like sertraline
Special Monitoring Considerations
Drug Interactions
- Monitor prothrombin time and INR if patient is also on warfarin, as sertraline can increase bleeding risk 2
- If patient is on other serotonergic medications, more frequent monitoring for signs of serotonin syndrome is warranted 5, 6
Specific Patient Populations
Elderly Patients
- More frequent monitoring of electrolytes and renal function (every 3-6 months)
- Lower threshold for LFT monitoring due to increased risk of adverse effects
Patients with Pre-existing Liver Disease
- More frequent LFT monitoring (every 1-3 months)
- Consider lower doses of both medications
Clinical Monitoring for Adverse Effects
While not laboratory tests, clinicians should monitor for:
- Signs of serotonin syndrome: agitation, confusion, diaphoresis, tremor, hyperreflexia, myoclonus, hyperthermia 2, 5, 6
- Behavioral changes: suicidal ideation, agitation, or worsening depression, especially in the first few weeks of treatment 2
- Bleeding: increased risk when sertraline is combined with NSAIDs, aspirin, or anticoagulants 2
Common Pitfalls and Caveats
- Asymptomatic elevations in liver enzymes are common with both medications but rarely lead to clinically significant hepatotoxicity 3, 4, 7
- Rapid dose escalation of both medications simultaneously increases risk of serotonin syndrome 5
- Monitoring should be more frequent when initiating therapy or changing doses
- False-positive urine immunoassay screening tests for benzodiazepines can occur in patients taking sertraline 2
- Laboratory abnormalities should be interpreted in the context of clinical symptoms
By following this monitoring protocol, clinicians can help ensure the safe use of sertraline and trazodone while minimizing the risk of adverse effects and detecting potential complications early.