What is the appropriate management for a patient with a ferritin of 1.9 ng/mL, normal serum iron, normal total iron‑binding capacity, and a transferrin level of 238 mg/dL?

Immediate Iron Replacement Therapy Required

This patient has severe iron deficiency (ferritin 1.9 ng/mL) and requires immediate iron supplementation, starting with oral iron therapy if tolerated, with consideration for intravenous iron if oral therapy fails or is not tolerated. 1

Interpretation of Laboratory Values

Your patient's ferritin of 1.9 ng/mL is critically low and definitively diagnostic of iron deficiency—well below any threshold used in clinical practice. For context:

• Ferritin <10 ng/mL is diagnostic of iron deficiency anemia 2
• Ferritin <45 ng/mL indicates iron deficiency in anemic patients 1
• Your patient's level of 1.9 ng/mL represents severe depletion of iron stores

The normal serum iron and TIBC can occur in iron deficiency and do not exclude the diagnosis. The transferrin level of 238 mg/dL is within normal range and consistent with the body's compensatory response to iron deficiency.

Treatment Algorithm

First-Line: Oral Iron Supplementation

Start oral iron immediately 1:

• Ferrous sulfate, ferrous fumarate, or ferrous gluconate are reasonable first choices (least expensive)
• Dosing: Standard formulations containing elemental iron
• Take on empty stomach for optimal absorption, though taking with meals is acceptable if better tolerated 1
• Add 500 mg vitamin C to enhance absorption 1
• Taking with meat protein further improves absorption 1

Common Pitfalls with Oral Iron

Expect gastrointestinal side effects (nausea, abdominal pain, constipation) that frequently limit adherence 1. If these occur, consider:

• Alternative oral formulations (e.g., ferrous bisglycinate may be better tolerated) 1
• Transition to intravenous iron if oral therapy is not tolerated or ineffective 1

Second-Line: Intravenous Iron

Consider IV iron initially if 1:

• Severe iron deficiency (which this patient has)
• Conditions affecting iron absorption
• Poor tolerance anticipated or documented with oral iron
• Need for rapid repletion

Diagnostic Workup Required

With ferritin this low, investigate the underlying cause 1:

1. Dietary assessment: Evaluate iron intake
2. Menstrual history (if premenopausal woman): Quantify blood losses
3. Gastrointestinal evaluation:
   • Test for Helicobacter pylori infection
   • Consider endoscopic evaluation (upper and lower GI) to identify blood loss or malabsorption
   • Assess for celiac disease

The 2024 AGA guideline emphasizes that after identifying iron deficiency, an appropriate diagnostic workup should be undertaken including evaluation of dietary iron intake and search for gastrointestinal conditions leading to poor iron absorption or blood loss 1.

Monitoring Response

• Recheck hemoglobin and ferritin after initiating therapy
• Target ferritin levels: Generally aim for >30-45 ng/mL to replete stores 1
• Adjust therapy based on tolerance and response
• Consider multidisciplinary management (gastroenterology, hematology, nutrition) for complex cases 1

Critical Point

A ferritin of 1.9 ng/mL represents profound iron depletion that will impact quality of life and requires urgent correction. The normal serum iron and TIBC do not negate this diagnosis—ferritin is the most reliable single marker for iron stores 2, and your patient's level indicates virtually absent iron reserves requiring immediate intervention.