From the Guidelines
Iron deficiency without anemia is characterized by symptoms such as poor athletic performance, fatigue, weakness, difficulty concentrating, headaches, hair loss, brittle nails, restless legs syndrome, and increased susceptibility to infections, and should be treated with oral iron supplementation and dietary changes to improve iron intake and absorption. The symptoms of iron deficiency without anemia can be subtle but impactful, and may include poor athletic performance, which is the most common presenting symptom in female athletes 1. Other symptoms may include fatigue, weakness, difficulty concentrating, headaches, hair loss, brittle nails, restless legs syndrome, and increased susceptibility to infections.
Treatment Options
Treatment primarily involves oral iron supplementation, and athletes with restrictive diets that make adequate consumption of iron difficult should consult a sports dietitian to optimize their daily nutrition plans for iron intake 1. The current USDA recommended daily allowance for girls 14–18 years old is 15 mg day −1 and for women 19–50 years old is 18 mg day−1, however, athletes with risk factors such as restrictive diets, high amounts of repetitive ground strikes, endurance training, and heavy menstrual bleeding should consume higher levels of iron on a daily basis 1.
- Oral iron supplementation, typically ferrous sulfate, can be taken to replenish iron stores
- Dietary changes, incorporating iron-rich foods such as red meat, spinach, beans, and fortified cereals, are also important to improve iron intake and absorption
- Athletes should be aware of the differences between iron deficiency and anemia, and that it is possible to be iron deficient without being anemic, and vice versa 1.
Key Considerations
Key considerations in the treatment of iron deficiency without anemia include identifying and addressing the underlying cause of iron deficiency, whether it's blood loss, poor dietary intake, malabsorption issues, or increased iron requirements during pregnancy or growth periods 1. Treatment typically continues for 3-6 months to replenish iron stores, with follow-up ferritin testing to monitor improvement. Side effects of oral iron supplementation may include constipation, nausea, and black stools, and alternative formulations like ferrous gluconate or iron polysaccharide may cause fewer gastrointestinal issues 1.
From the Research
Symptoms of Iron Deficiency without Anemia
- Fatigue, irritability, depression, difficulty concentrating, restless legs syndrome (32%-40%), pica (40%-50%), dyspnea, lightheadedness, exercise intolerance, and worsening heart failure (HF) 2
- Nonhematological manifestations of iron deficiency may give rise to unpleasant symptoms such as fatigue, reduced physiological endurance, difficulty in regulating temperature, decreased cognitive performance 3
- Unexplained, non-specific symptoms, low ferritin and low transferrin saturation with a normal haemoglobin concentration 4
Treatment Options for Iron Deficiency without Anemia
- Oral iron (ferrous sulfate 325 mg/d or on alternate days) is typically first-line therapy 2
- Intravenous iron is indicated for patients with oral iron intolerance, poor absorption (celiac disease, post-bariatric surgical procedure), chronic inflammatory conditions (CKD, HF, IBD, cancer), ongoing blood loss, and during the second and third trimesters of pregnancy 2
- Oral iron supplements, with iron studies repeated after 60-90 days of oral iron supplements 4
- Intravenous iron may be beneficial for some patients, including those who have not responded to oral supplements 4
Diagnosis of Iron Deficiency without Anemia
- Diagnosing iron deficiency without anemia relies on a combination of tests, including haemoglobin and ferritin levels, as well as transferrin saturation 5
- 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
- Iron studies will usually show a low ferritin and low transferrin saturation with a normal haemoglobin concentration 4