Laboratory Monitoring for Keppra (Levetiracetam)
Complete blood count (CBC) monitoring is recommended when initiating Keppra therapy, but routine therapeutic drug level monitoring is not necessary for most patients. 1, 2, 3, 4
Required Baseline Laboratory Tests
Before starting Keppra, obtain the following:
- Complete blood count (CBC) with differential 1, 2, 3, 4
- Liver function tests (LFTs) including AST, ALT, alkaline phosphatase, and bilirubin 4
- Renal function tests including BUN and creatinine 4
- Pregnancy test in women of childbearing potential 4
Ongoing Monitoring Requirements
Hematologic Monitoring
Monitor CBC periodically during treatment, though no specific frequency is mandated. 1, 2, 4 The FDA label notes that levetiracetam causes small mean decreases in total WBC (approximately -0.4 × 10⁹/L) and neutrophil counts (approximately -0.3 × 10⁹/L), with relative lymphocyte count increases of 1.7%. 4 In controlled trials, 3.0% of levetiracetam-treated patients had clinically significant low WBC values compared to 0% on placebo, though no patients required discontinuation for this reason. 4
Liver Function Monitoring
Routine LFT monitoring is not systematically required. 4 The FDA label states there were no meaningful changes in mean liver function tests in controlled trials, and LFT abnormalities were similar between drug and placebo groups (1.4%). 4 Only 1 patient (0.07%) was discontinued from trials for LFT abnormalities. 4
Renal Function Monitoring
For patients with renal impairment, monitor levels every 3-6 months. 2 Since levetiracetam clearance is primarily renal (66% excreted unchanged in urine), dosage adjustments are necessary for moderate to severe renal impairment. 5
Therapeutic Drug Monitoring
Levetiracetam does not require routine therapeutic drug monitoring. 1, 2 The therapeutic serum concentration range is 10-37 mcg/mL, but levels do not need to be checked routinely. 6
Specific Situations Where Level Monitoring May Be Considered
- Suspected medication non-adherence 2, 3
- Renal impairment requiring dose adjustment 2, 5
- Suspected toxicity (though overdose is managed supportively) 6
Key Monitoring Pitfalls to Avoid
Do not discontinue therapy based solely on mild WBC decreases. 4 Small decreases in WBC and neutrophil counts are expected and do not typically require intervention unless accompanied by clinical signs of infection or values become severely abnormal.
Do not assume drug interactions require monitoring. 4, 5 Levetiracetam has minimal drug interactions because it is not metabolized by hepatic cytochrome P450 enzymes, does not undergo hepatic glucuronidation, and is minimally protein-bound (<10%). 4, 5 No clinically relevant pharmacokinetic interactions with other antiepileptic drugs have been identified. 4, 5