To evaluate your body’s current store or iron
Your doctor may request that you fast for 12 hours prior to some iron blood tests. In this case, only water is permitted. You should not take any iron tablets for 24 hours before the test. Iron is absorbed rapidly from food or tablets, and can make your blood iron levels falsely high.
Serum iron blood tests are not performed routinely. Most often, serum iron levels are tested if your doctor thinks that you might have too much iron in your blood.
If your result is “negative,” you most likely don’t have a problem with blood clots, such as DVT. If your result is “high,” it means you’ll need more testing to see whether you have a blood clot. This test can’t confirm that you have DVT or PE. It can only help rule them out.