|  | 
Medical Definition of Active formaldehyde
1. A hydroxymethyl derivative of tetrahydrofolate or thiamin pyrophosphate, N5,N10-methylenetetrahydrofo late. (05 Mar 2000)
|  | 
1. A hydroxymethyl derivative of tetrahydrofolate or thiamin pyrophosphate, N5,N10-methylenetetrahydrofo late. (05 Mar 2000)