Does iron testing require special preparation?

From the Guidelines

Iron testing should be done in the morning, after avoiding all iron-containing supplements and foods for at least 24 hours prior to blood draw. This is based on expert consensus from the American Academy of Sleep Medicine clinical practice guideline published in 2025 1.

Key Considerations for Iron Testing

• The test should ideally be administered in the morning to ensure accurate results, as iron levels can fluctuate throughout the day.
• Patients should avoid all iron-containing supplements and foods at least 24 hours prior to blood draw, as these can influence test results.
• Analysis of iron studies, including ferritin and transferrin saturation, is crucial in determining the need for oral or intravenous iron treatment, particularly in patients with restless legs syndrome (RLS) 1.

Importance of Accurate Iron Testing

• Accurate iron testing is essential for proper diagnosis and treatment of conditions like anemia or iron overload.
• In patients with RLS, iron supplementation guidelines differ from those for the general population, and accurate testing is necessary to determine the need for oral or intravenous iron treatment 1.
• By following these guidelines, healthcare providers can ensure that test results accurately reflect a patient's true iron status, leading to better treatment outcomes and improved quality of life.

From the Research

Iron Testing Preparation

• The need for special preparation for iron testing is not explicitly stated in the provided studies 2, 3, 4, 5, 6.
• However, the oral iron absorption test (OIAT) involves giving patients ferrous sulphate tablets and evaluating iron levels in the blood at intervals from 30 to 180 minutes after iron administration 2.
• This suggests that some preparation, such as fasting or avoiding iron-rich foods, may be necessary to ensure accurate results, but this is not clearly stated in the studies.
• The studies focus more on the treatment and management of iron deficiency rather than the preparation for iron testing 3, 4, 5, 6.

Iron Testing Methods

• The OIAT is a simple test that can be conducted in any outpatient clinic to determine the degree of oral iron absorption 2.
• Other methods for assessing iron nutritional status include laboratory tests that focus on storage, transportation, and iron functional compartment parameters 6.
• Classical markers such as bone marrow, serum iron, ferritin, hemoglobin, erythrocyte parameters, transferrin, transferrin receptors, and zinc protoporphyrin are used to assess iron status 6.
• Emergent parameters such as hepcidin, erythroferrone, and low hemoglobin density are also being considered for assessing iron nutritional status 6.

Special Considerations

• Inflammation or infection can influence many of the indicators used to assess iron nutritional status, so this should be taken into account when interpreting test results 6.
• The use of more than one indicator may be the best practice to obtain an accurate diagnosis of iron deficiency 6.