Serum iron measures the amount of iron present in the blood, specifically in the serum. Iron is an essential mineral for the production of hemoglobin, which carries oxygen in red blood cells.

 Importance: This test helps in diagnosing iron deficiency anemia or iron overload conditions such as hemochromatosis.

 When is it done?: The test is typically ordered when a patient shows symptoms of anemia or when there is suspicion of an iron metabolism disorder, such as low iron stores or excess iron levels. It is also used to monitor patients with chronic blood loss or treatment of iron supplementation.