Trace metals in hematopoiesis.

The trace metals represent an extremely small part of the total mass of the organism. In spite of this, these elements appear to play major roles in metabolism. At the level of the hematopoietic system, specific roles can be identified for iron, copper, zinc, and cobalt. Other trace metals appear to play less clearly defined roles in hematopoiesis but clearly are involved by virtue of a number of interactions at the level of absorption, intermediary metabolism, or modulation of toxicity. Still other trace metals, such as lithium, appear to have a therapeutic role in altering production of granulocytes, by an as yet unidentified mechanism.