Do Quetiapine (quetiapine), lithium, and Luvox (fluvoxamine) cause thrombocytopenia (low platelet count)?

Medication-Induced Thrombocytopenia: Quetiapine, Lithium, and Fluvoxamine

Quetiapine can cause thrombocytopenia in rare cases, while lithium typically does not cause clinically significant thrombocytopenia. There is insufficient evidence regarding fluvoxamine's effect on platelet counts, but other SSRIs can potentially affect platelet function.

Quetiapine and Thrombocytopenia

Quetiapine has been associated with hematological adverse effects, including thrombocytopenia:

• The American Academy of Child and Adolescent Psychiatry guidelines note that while hematological toxicity is primarily associated with clozapine, there is a documented case of "a precipitous drop in ANC and platelets in a 12-year-old boy receiving quetiapine" 1.

• The FDA drug label for quetiapine lists "decreased platelets" among reported adverse reactions 2.

• Case reports have documented quetiapine-associated thrombocytopenia:

  • A Han-Chinese patient developed leucopenia and thrombocytopenia after taking 400 mg/day of quetiapine for three and a half months 3.
  • Another case report described thrombocytopenia with a platelet count dropping to 0.5 × 10⁴/μL in a patient on maintenance dialysis after quetiapine administration 4.
  • A 2007 case report also documented leucopenia and thrombocytopenia with quetiapine treatment that required discontinuation 5.

Lithium and Thrombocytopenia

• Research indicates that lithium typically does not cause thrombocytopenia and may actually increase platelet counts:
  • A study examining patients treated with lithium carbonate found that platelet counts were actually increased in subjects treated with lithium without additional psychotropic medication, though this increase was not clinically significant 6.

Fluvoxamine (Luvox) and Thrombocytopenia

• There is limited specific evidence regarding fluvoxamine's effect on platelet counts in the provided literature.
• However, selective serotonin reuptake inhibitors (SSRIs) as a class can impair platelet function as noted in a review of drugs affecting platelet function 7.

Clinical Implications and Monitoring

Risk Assessment

• Thrombocytopenia risk appears highest with quetiapine among the three medications.
• The risk of thrombocytopenia with these medications is generally low but should be considered in:
  • Patients with preexisting hematological disorders
  • Patients on multiple medications that may affect platelet function
  • Patients showing signs of bleeding or bruising

Monitoring Recommendations

• For patients on quetiapine:

  • Baseline complete blood count (CBC) before initiating treatment
  • Periodic monitoring of CBC during treatment, especially in the first few months
  • Immediate CBC if signs of bleeding, bruising, or infection develop

• For patients on lithium:

  • Routine CBC monitoring as part of standard lithium monitoring
  • No specific additional monitoring for thrombocytopenia is required based on current evidence

• For patients on fluvoxamine:

  • Consider baseline CBC before initiating treatment
  • Monitor for clinical signs of bleeding, particularly if combined with other medications affecting platelet function

Management of Medication-Induced Thrombocytopenia

• If thrombocytopenia develops:

  • Consider discontinuation of the suspected medication, particularly quetiapine
  • Monitor platelet counts until recovery
  • Quetiapine-associated thrombocytopenia appears reversible upon discontinuation 3, 4

• According to the Association of Anaesthetists of Great Britain & Ireland guidelines, platelet counts below 75 × 10⁹/L are considered high risk, and counts below 50 × 10⁹/L are considered very high risk for bleeding complications 1.

Conclusion

Quetiapine has documented cases of causing thrombocytopenia, though this is a rare adverse effect. Lithium does not appear to cause clinically significant thrombocytopenia and may actually increase platelet counts. The evidence for fluvoxamine is limited, but as an SSRI, it may affect platelet function rather than count. Monitoring of complete blood counts is recommended, particularly for patients on quetiapine.