What laboratory tests are recommended for patients on Keppra (levetiracetam)?

Laboratory Monitoring for Patients on Keppra (Levetiracetam)

No routine therapeutic drug level monitoring is required for patients on levetiracetam therapy. Unlike many other antiepileptic drugs, levetiracetam does not require regular blood level monitoring in most patients 1.

Baseline Laboratory Tests

Before initiating levetiracetam therapy, the following baseline tests are recommended:

• Complete blood count (CBC) to establish baseline hematologic parameters 1, 2
• Liver function tests (LFTs) including ALT, AST, alkaline phosphatase, and bilirubin to screen for pre-existing liver disease 2

Monitoring After Initiation

Hematologic Monitoring

• Monitor CBC periodically, especially during the first few months of therapy 2
• Pay particular attention to white blood cell (WBC) and neutrophil counts, as minor but statistically significant decreases have been observed in levetiracetam-treated patients compared to placebo 2
• In clinical trials, 3.2% of treated patients had at least one possibly significant decreased WBC (≤2.8 × 10^9/L) and 2.4% had decreased neutrophil counts (≤1.0 × 10^9/L) 2

Hepatic Monitoring

• Although no meaningful changes in mean liver function tests were observed in controlled trials, periodic monitoring of LFTs is prudent 2
• Levetiracetam appears to be well-tolerated in patients with chronic liver disease, with some patients even showing normalization of liver enzymes during treatment 3

Special Populations

Patients with Renal Impairment

• More frequent monitoring may be necessary for patients with renal impairment since levetiracetam is primarily eliminated through the kidneys 4
• Dosage adjustments are necessary for patients with moderate to severe renal impairment 4

Pediatric Patients

• In pediatric patients, monitor for decreases in WBC and neutrophil counts, which were statistically significant compared to placebo in clinical trials 2
• Mean decreases from baseline in levetiracetam-treated pediatric patients were –0.4 × 10^9/L for WBC and –0.3 × 10^9/L for neutrophils 2

Clinical Considerations

• Levetiracetam has minimal drug interactions, making it suitable for patients on multiple medications 1
• The elimination half-life of levetiracetam is 6-8 hours in adults with epilepsy, 5-7 hours in children with epilepsy, and 10-11 hours in elderly patients 4
• Approximately 66% of levetiracetam is excreted unchanged in urine, with only 34% being metabolized 4

When to Consider Level Monitoring

While routine therapeutic drug monitoring is not required, consider checking levetiracetam levels in:

• Patients with suspected medication non-adherence 1
• Cases of intentional overdose (therapeutic serum concentration is 10-37 μg/mL) 5
• Patients with significant renal impairment 4

Common Pitfalls to Avoid

• Failing to obtain baseline laboratory tests, which may lead to difficulty interpreting subsequent abnormalities 6
• Overlooking the need for dosage adjustments in patients with renal impairment 4
• Unnecessary monitoring of drug levels in routine cases, as levetiracetam has a wide therapeutic window and predictable pharmacokinetics 1, 4