What is the best specimen to test for levels of iron in the blood?

The testing of iron levels in the blood requires a specimen that accurately reflects the concentration of iron, which is typically measured through serum assays. The best specimen for this purpose is blood collected in a tube containing EDTA, which is an anticoagulant.

EDTA prevents the blood from clotting, allowing for the accurate measurement of the serum or plasma levels of various substances, including iron. When blood is anticoagulated with EDTA, it maintains the stability and integrity of the iron in the sample, minimizing any changes due to metabolic activities or clot formation that can affect the results.

Other types of tubes, such as those containing heparin or a serum separator, may lead to variations in the results for iron levels. Heparin can also affect iron metabolism and may not provide the same reliability. Similarly, tubes designed for serum separation may involve clotting which could influence iron levels due to the release of iron from cells during the clotting process. Thus, EDTA is preferred for iron testing to ensure accurate and precise results.