From the Guidelines
Low ferritin levels with high hemoglobin (Hb) levels indicate iron deficiency without anemia, and medical evaluation is necessary to determine the underlying cause and appropriate treatment. This condition can be caused by various factors, including early iron deficiency, polycythemia vera, or dehydration. According to the study by 1, iron deficiency is defined as low serum ferritin (<35 μg/L) and normal blood hemoglobin values, and it is typically tested for by determining serum ferritin, the most established marker for the amount of stored iron. The British Society of Gastroenterology guidelines 1 also recommend that iron deficiency should be confirmed by iron studies prior to investigation, and serum ferritin is the single most useful marker of iron deficiency anemia. Some key points to consider in this situation include:
- Possible causes: early iron deficiency, polycythemia vera, dehydration
- Diagnosis: serum ferritin, transferrin saturation, and hemoglobin levels
- Treatment: iron supplementation (e.g., ferrous sulfate 325mg once or twice daily) for low ferritin, and addressing underlying causes
- Important considerations: taking iron supplements with vitamin C enhances absorption, while calcium and certain foods can inhibit it, and side effects may include constipation and stomach upset. It is essential to evaluate this combination of lab results with a healthcare provider to determine the appropriate treatment approach and rule out serious conditions. In terms of prevention, maintaining a diet rich in iron, particularly red meat, is recommended to avoid the development of overt anemia and ensure that other hem-containing proteins/enzymes can be maintained at a sufficient level 1. Additionally, vitamin C should be co-ingested with non-haem iron sources to enhance absorption, and foods or fluids that impair iron absorption, such as tea and coffee, should be avoided around meal times 1.
From the Research
Significance of Low Ferritin Levels with High Hemoglobin (Hb) Levels
- Low ferritin levels indicate iron deficiency, which can occur even with high hemoglobin levels 2.
- Iron deficiency can affect cognitive function and physical performance, and treatment is recommended even in the absence of anemia 2.
- A ferritin cut-off of 30 µg/l is appropriate for healthy males and females aged >15 years, while cut-offs of 15 and 20 µg/l are recommended for children from 6-12 years and younger adolescents from 12-15 years, respectively 2.
Diagnosis and Treatment of Iron Deficiency
- Iron deficiency anemia is diagnosed by identification of microcytic hypochromic anemia with low serum ferritin levels 3.
- Treatment of underlying diseases is recommended along with iron supplementation, and oral iron supplements are the first choice 3.
- Intravenous iron may be considered when oral administration is impractical, iron absorption is impaired, or rapid iron replenishment is necessary 3, 4.
Optimal Serum Ferritin Levels
- Optimal serum ferritin levels for oral iron therapy in hemodialysis patients with iron deficiency anemia and minor inflammation are estimated to be 30-40 ng/mL 5.
- A serum ferritin level <100 ng/ml or a transferrin saturation (TSAT) <20% is currently used to define iron deficiency in patients with chronic heart failure, but this criteria may not be supported by pathophysiological or clinical evidence 6.
Iron Repletion Strategies
- Intravenous iron therapy may be effective and safe for management of iron deficiency anemia, and can decrease the risk of cardiovascular death or total heart failure hospitalization in patients with a TSAT <20% 4, 6.
- A new mechanism-based and trial-tested approach is recommended to define iron deficiency in patients with heart failure, using a TSAT <20% (as long as the serum ferritin level is <400 μg/L) as a diagnostic criterion 6.