What is the significance of low iron saturation and ferritin levels in a 32-year-old female taking 325mg of iron (ferrous sulfate) daily, with laboratory results showing hypoferritinemia and elevated Total Iron-Binding Capacity (TIBC)?

From the Guidelines

This patient's iron deficiency anemia is not adequately managed with her current oral iron supplementation, and I strongly recommend switching to intravenous (IV) iron therapy to rapidly improve her iron parameters and alleviate symptoms. Based on the lab results, this 32-year-old female patient has iron deficiency anemia with a low ferritin level of 8 ng/mL, low iron saturation of 12%, and elevated TIBC of 452-465 mcg/dL, indicating a significant iron deficit despite being on oral iron 325 mg daily for at least 2 months 1. The fact that her iron parameters have not improved significantly with oral iron supplementation suggests that she may have ongoing losses or malabsorption, which would require more aggressive treatment.

Key points to consider in this patient's management include:

• The frequency of administration and duration of benefit of IV iron is dependent on the underlying etiology of the iron deficiency, and in this case, may require multiple administrations 1
• Laboratory evaluation following IV iron should include a CBC and iron parameters (ferritin, percent transferrin saturation) 4 to 8 weeks after the last infusion, as circulating iron can interfere with assay results within 4 weeks of treatment 1
• The goal ferritin level is 50 ng/mL, regardless of sex, and a TSAT <20% has high sensitivity for diagnosing absolute or functional iron deficiency 1
• Further investigation into the cause of her iron deficiency is warranted, including evaluation for chronic blood loss, malabsorption disorders, or dietary insufficiency

Given the patient's lack of response to oral iron and the potential for ongoing losses or malabsorption, IV iron therapy is the most appropriate next step to rapidly replenish her iron stores and improve her symptoms. A follow-up with repeat labs in 4-6 weeks is recommended to assess response to the adjusted therapy 1.

From the FDA Drug Label

Purpose Iron Supplement Therapy Ferrous Sulphate is an iron supplement for iron deficiency and iron deficiency anemia when the need for such therapy has been determined by a physician. Active ingredients (in each Caplet) Dried Ferrous Sulfate 325 mg

The patient is currently taking 325 mg of iron daily. Based on the lab results, the patient has:

• Low iron levels: 54 mcg/dL (2 wk ago) and 55 mcg/dL (2 mo ago)
• High TIBC: 452 mcg/dL (2 wk ago) and 465 mcg/dL (2 mo ago)
• Low iron saturation: 12% (2 wk ago) and 12% (2 mo ago)
• Low ferritin: 8

The patient's lab results indicate iron deficiency, and the patient is already taking iron supplement therapy. The current dosage of 325 mg of iron daily is consistent with the drug label 2. However, the effectiveness of this dosage in addressing the patient's iron deficiency is unclear based on the provided information.

From the Research

Iron Deficiency Diagnosis

• The patient's iron level is 54 mcg/dL, which is within the normal range of 37-145 mcg/dL.
• The patient's TIBC (Total Iron-Binding Capacity) is high at 452 mcg/dL, indicating that the body has a high capacity to bind iron, but the iron saturation is low at 12%, suggesting that the body's iron stores are not being utilized efficiently.
• The patient's ferritin level is 8, which is an indicator of iron stores, and is lower than the normal range.

Relevance of Transferrin Saturation

• A study published in 2019 3 suggests that using transferrin saturation as a diagnostic criterion for iron deficiency can be beneficial, especially in patients with chronic inflammatory diseases.
• The study recommends using transferrin saturation in addition to ferritin for the diagnosis of iron deficiency.

Current Treatment

• The patient is currently taking 325mg of iron daily, which may help to increase iron stores and improve iron saturation.
• However, the patient's iron saturation and ferritin levels suggest that the current treatment may not be sufficient to address the iron deficiency.

Other Studies

• Two other studies 4, 5 are not relevant to the diagnosis and treatment of iron deficiency, as they discuss topics unrelated to iron deficiency, such as knee prostheses and cardiac aneurysms.