Polychromasia is usually a sign of bone marrow stress as well as immature red blood cells.

Erythropoetin, a hormone made by the kidneys, controls the production of red blood cells as well as the rate at which they are released from the bone marrow.

When these levels of erythropoetin rise, they signal the release of immature red blood cells into the bloodstream and is linked to anemia.

Because there are more red blood cells needed in the body at that moment, they are released prematurely, leading to polychromasia.

It is much easier to test for polychromasia in blood cells than to perform special staining for reticulocytosis.

If polychromasia is found in the blood cells, the reticulocyte count is taken to detect further disease or stress.

Polychromasia occurs when the immature reticulocytes of the bone marrow are released, resulting in a grayish blue color of the cells.

[citation needed] Polychromasia can be detected through the use of stains that will change the color of the red blood cells that are affected.

[citation needed] In 1890, research done by William Henry Howell indicated that certain red blood cells found both in fetal circulation and bone marrow (of a cat) had unusual granulation.

Stippling is supposed to be one of the earliest symptoms of lead poisoning, although most scientists now regard it as a degenerative condition, along with polychromasia.