"The only way to accurately diagnose iron overload is with the correct blood work. Serum iron alone is not accurate. It reflects iron in the diet but not how much is stored. Transferrin is the protein that carries iron in the blood. When transferrin and iron are both measured, the percent transferrin saturation can be calculated by dividing serum iron by transferrin and multiplying by 100. That % is useful in interpreting the third test that is needed, ferritin. Ferritin is a measure of the body’s total iron content. High ferritin can mean iron overload but chronic disease involving inflammation or infection may also elevate ferritin.

With true iron overload, transferrin saturation is high normal or elevated. There is currently only one laboratory in the world that can measure equine ferritin, the comparative hematology laboratory at Kansas State Veterinary Diagnostic Laboratory. "