What management is recommended for a patient with marginal iron stores, normal serum iron, elevated transferrin, and normal transferrin saturation?

Management of Marginal Iron Stores with Normal Serum Iron

Initiate oral iron supplementation immediately with ferrous bisglycinate or ferrous sulfate 30-60 mg elemental iron daily, as this patient has confirmed iron deficiency based on a ferritin of 19 μg/L, which is below the diagnostic threshold of <20 μg/L that is highly specific for depleted iron stores. 1

Understanding the Laboratory Pattern

Your patient presents with a classic early-stage iron deficiency pattern:

• Ferritin 19 μg/L indicates depleted iron stores - this is below the 20 μg/L threshold that confirms iron deficiency with 98% specificity in women of childbearing age 1
• Elevated transferrin (4.08 g/L) is the body's compensatory response - transferrin increases when iron stores are low to maximize iron-binding capacity 1
• Normal serum iron (21 μmol/L) and transferrin saturation (23%) indicate this is Stage 1 iron deficiency - iron stores are depleted but the body is still maintaining adequate circulating iron for immediate erythropoiesis 2
• This represents iron deficiency without anemia - hemoglobin remains normal in early iron deficiency, but symptoms like fatigue and reduced exercise tolerance are still common 2

Treatment Protocol

Oral Iron Supplementation:

• Start ferrous bisglycinate or ferrous sulfate 30-60 mg elemental iron daily 2
• Consider alternate-day dosing (60 mg every other day) to improve absorption and reduce gastrointestinal side effects compared to daily dosing 2
• Take on empty stomach for optimal absorption, or with meals if gastrointestinal symptoms (constipation, nausea, diarrhea) occur 2
• Target ferritin >100 ng/mL to restore iron stores and prevent recurrence 2

Investigation Strategy

The approach to investigating the underlying cause depends on patient demographics and risk factors:

For premenopausal women:

• GI investigation is not mandatory unless red flags are present (age ≥50 years, GI symptoms, family history of colorectal cancer, failure to respond to iron therapy) 2
• Screen for celiac disease with tissue transglutaminase antibodies - present in 3-5% of iron deficiency cases 2
• Test for H. pylori non-invasively (stool antigen or urea breath test) 2
• Assess menstrual blood loss history - the most common cause in premenopausal women 2

Reserve bidirectional endoscopy for:

• Age ≥50 years (higher malignancy risk) 2
• New or worsening GI symptoms (abdominal pain, change in bowel habits, blood in stool) 2
• Positive celiac or H. pylori testing requiring confirmation 2
• Failure to respond to adequate oral iron therapy after 8-10 weeks 2

Follow-Up and Monitoring

• Repeat CBC and ferritin in 8-10 weeks to assess response to treatment 2
• If no improvement, consider: malabsorption (celiac disease, inflammatory bowel disease), non-compliance, ongoing blood loss, or need for IV iron 2
• For patients with recurrent low ferritin (menstruating females, vegetarians, athletes), screen ferritin every 6-12 months 2
• Do not continue daily iron supplementation once ferritin normalizes - this is potentially harmful 2

Critical Pitfalls to Avoid

Do not be falsely reassured by the normal serum iron and transferrin saturation - ferritin is the earliest and most specific marker of iron deficiency, and a level of 19 μg/L definitively confirms depleted iron stores requiring treatment 1, 2

Do not delay treatment while investigating - start oral iron supplementation immediately, as iron deficiency without anemia still causes significant symptoms including fatigue and reduced exercise tolerance 2

Do not overlook celiac disease - it is present in 3-5% of iron deficiency cases and can be easily missed without serologic screening 2

Do not perform extensive GI investigation in young, asymptomatic premenopausal women with heavy menses - the yield is extremely low (0-6.5%) 2