Mayahara_2026_Clin.Biochem__111109

Routine "serum cholinesterase" testing primarily reflects butyrylcholinesterase (BuChE) activity and may not exclude toxicity from relatively acetylcholinesterase (AChE)-selective agents such as donepezil and galantamine. We conducted a targeted PubMed/MEDLINE search through December 2025 and identified published reports with documented cholinesterase measurements in clinically significant toxicity. Across these cases, serum BuChE and/or erythrocyte AChE activity was reported within the stated reference range despite symptomatic overdose. Potential explanations include limited BuChE inhibition by these agents and assay-related underestimation of reversible AChE inhibition under dilutional conditions. Normal serum cholinesterase should therefore not be used to rule out donepezil or galantamine toxicity; clearer test labeling as BuChE activity may reduce misinterpretation.