"A normal or increased hemoglobin (oxygen carrying) level combined with symptoms usually associated with low hemoglobin such as anemia are often indicative of mercury toxicity. Copper is also required to prevent anemia, and mercury can compete for copper's binding sites. A lowered hematocrit (red blood cell count) can be indicative of lowered blood copper levels. "

http://www.evenbetternow.com/heavy-metal-poisoning-mercury.asp