My DMSA is always higher than my ALA, I can't get past 0.5mg/lbs of ALA no matter what I do.
But...spiking is a better way to chelate lead. Where before I would take 1mg/lbs of DMSA each dose I now take 0.5mg and spike to 3mg once or twice a day as needed.
NOTE: During a heavy Lead dump this took care of most of the problem in just 3 days...