From the Guidelines
Very low serum ferritin levels are a significant indicator of iron deficiency, which can lead to iron deficiency anemia if left untreated, and should be addressed with iron supplementation and treatment of the underlying cause, as recommended by the most recent guidelines 1.
Significance of Very Low Serum Ferritin
Very low serum ferritin levels indicate depleted iron stores in the body, often occurring before anemia develops. According to the most recent guidelines, a serum ferritin level < 30 mg/L is an appropriate criterion for the diagnosis of iron deficiency anemia in patients without clinical, endoscopic, or biochemical evidence of active disease 1.
Diagnosis and Treatment
In the presence of inflammation, a serum ferritin up to 100 mg/L may still be consistent with iron deficiency 1. Iron supplementation is recommended in all patients with iron-deficiency anemia, and intravenous iron should be considered as first-line treatment in patients with clinically active disease, previous intolerance to oral iron, or hemoglobin below 100 g/L 1.
Key Points to Consider
- Very low serum ferritin levels indicate iron deficiency and require iron supplementation.
- The underlying cause of iron deficiency must be identified and addressed.
- Treatment should continue for 3-6 months even after blood counts normalize to fully replenish iron stores.
- Intravenous iron may be necessary in patients with clinically active disease or previous intolerance to oral iron.
- Serum ferritin levels should be monitored to determine the need for re-treatment with intravenous iron 1.
From the Research
Significance of Very Low Serum Ferritin
- Very low serum ferritin levels are a significant indicator of iron deficiency, which affects approximately 2 billion people worldwide and 14% of adults in the US 2.
- Iron deficiency can progress from low iron stores to iron-deficiency anemia, and individuals may experience symptoms such as fatigue, irritability, depression, difficulty concentrating, and restless legs syndrome 2.
- The most common causes of iron deficiency are bleeding, impaired iron absorption, inadequate dietary iron intake, and pregnancy 2.
- Testing for iron deficiency is indicated for patients with anemia and/or symptoms of iron deficiency, and should be considered for those with risk factors such as heavy menstrual bleeding, pregnancy, or inflammatory bowel disease 2.
Diagnosis and Treatment of Iron Deficiency
- Iron deficiency is diagnosed by low serum ferritin (typically <30 ng/mL) in individuals without inflammatory conditions or by transferrin saturation (iron/total iron binding capacity × 100) less than 20% 2.
- Oral iron is typically first-line therapy, while intravenous iron is indicated for patients with oral iron intolerance, poor absorption, chronic inflammatory conditions, ongoing blood loss, and during the second and third trimesters of pregnancy 2, 3, 4.
- The choice of iron formulation and dosing strategy depends on the individual patient's needs and circumstances, and evidence-based recommendations have been developed for the management of iron deficiency in children, adults, and pregnant individuals 5.
Ferritin as a Diagnostic Test
- Ferritin is an iron storage protein and its concentration in the plasma or serum reflects iron stores, with low ferritin indicating iron deficiency and elevated ferritin reflecting risk of iron overload 6.
- The use of ferritin as a diagnostic test of iron deficiency and overload is a common clinical practice, but its accuracy can be affected by inflammation and infection 6.
- Studies have shown that ferritin concentration is a reasonably sensitive and specific test for iron deficiency in people presenting for medical care, but its performance in asymptomatic individuals is less clear 6.