What is the significance of low iron saturation, specifically 9%?

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Last updated: May 16, 2025View editorial policy

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From the Guidelines

An iron saturation level of 9% is considered low, indicating iron deficiency, and according to the most recent guidelines 1, iron supplementation is likely necessary to prevent complications such as fatigue, weakness, and anemia.

Diagnosis and Treatment

To confirm the diagnosis, a healthcare provider will likely assess serum ferritin levels and transferrin saturation (TSAT) in addition to the iron saturation level.

  • Normal iron saturation typically ranges from 20-50%
  • A TSAT < 20% has high sensitivity for diagnosing absolute or functional iron deficiency 1
  • Ferritin levels can also be used to evaluate iron stores, with a goal ferritin of 50 ng/mL in the absence of inflammation 1

Iron Supplementation

Iron supplementation, typically ferrous sulfate 325mg taken 1-3 times daily between meals with vitamin C to enhance absorption, is likely recommended.

  • It is essential to avoid taking iron with calcium, dairy, coffee, tea, or antacids as these can reduce absorption
  • Side effects may include constipation, dark stools, and stomach upset

Monitoring Progress

Regular blood tests will be needed to monitor progress until iron levels normalize.

  • Laboratory evaluation following iron supplementation should include a complete blood count (CBC) and iron parameters (ferritin, TSAT) 4 to 8 weeks after the last infusion 1
  • Hemoglobin concentrations should increase within 1–2 weeks of treatment and should increase by 1 to 2 g/dL within 4–8 weeks of therapy 1

From the Research

Iron Saturation

  • Iron saturation, also known as transferrin saturation (TSAT), is a measure of the amount of iron bound to transferrin, a protein that carries iron in the blood 2, 3.
  • A TSAT of 9% is considered low, indicating iron deficiency 3.
  • Iron deficiency can be diagnosed by measuring serum ferritin, which is an index of iron stores, and serum transferrin receptor, which is an index of tissue iron deficiency 2.
  • The treatment of iron deficiency typically involves oral iron supplementation, but parenteral iron can be given in cases of large blood losses, iron malabsorption, or intolerance to oral iron 2, 3.

Diagnostic Criteria

  • The American Journal of Clinical Nutrition study 3 recommends a cutoff of 100 μg/L for serum ferritin concentration and 20% for TSAT for the diagnosis of iron deficiency in most conditions.
  • However, the optimal diagnostic approach is to measure both serum ferritin and serum transferrin receptor to confirm iron deficiency 2.

Treatment Targets

  • Treatment targets for iron deficiency include an increase in hemoglobin concentrations to 10-12 g/dL or normalization, and serum ferritin >100 μg/L or 200 μg/L 3.
  • TSAT is also recommended as a target, with various thresholds ranging from 20% to 50% 3.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Diagnosis and management of iron-deficiency anaemia.

Best practice & research. Clinical haematology, 2005

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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