Factitious lithium toxicity secondary to lithium heparin-containing blood tubes.

Introduction: Lithium concentrations analyzed from blood collected in inappropriate tubes may lead to misdiagnosis and lead to unnecessary hospitalization and intervention. We sought to assess the magnitude of falsely elevated lithium levels in green top lithium heparin-containing blood tubes.

Methods: Serum lithium concentrations from two types of commonly used standard green top tubes were evaluated against a control tube.