Based on a hemoglobin of 13.1 g/dL (reference range starting at 14 g/dL), ferritin of 20.5 ng/mL, and transferrin saturation of 24% measured 8 months ago, do I have iron‑deficiency anemia, iron deficiency without anemia, or no iron deficiency?

Iron Deficiency Without Anemia

You have iron deficiency without anemia. Your hemoglobin of 13.1 g/dL is below your facility's reference range (≥14 g/dL) but above the threshold that defines anemia in most clinical contexts, while your ferritin of 20.5 ng/mL confirms depleted iron stores.

Diagnostic Classification

Your laboratory values fit the following pattern:

• Hemoglobin 13.1 g/dL: This is below your local reference range but typically above the WHO anemia threshold for adult males (13 g/dL) or females (12 g/dL). The declining trend from 13.8 to 13.1 g/dL suggests progressive iron depletion. 1

• Ferritin 20.5 ng/mL: This definitively confirms iron deficiency. In adults without inflammation, ferritin <30 ng/mL is diagnostic of absolute iron deficiency. 2, 1, 3 Your ferritin is well below this threshold, indicating severely depleted iron stores.

• Transferrin saturation 24%: Although measured 8 months ago and now potentially outdated, this value was above the diagnostic threshold for iron deficiency (<16-20%). 2, 4 However, TSAT can remain falsely normal early in iron deficiency before stores are completely exhausted, and your current ferritin confirms true deficiency regardless of the prior TSAT. 4

Why This Matters Clinically

Iron deficiency without anemia is a distinct clinical entity that causes symptoms and warrants treatment. You are in the early-to-intermediate stage of iron deficiency, where stores are depleted (low ferritin) but hemoglobin has not yet fallen to anemic levels. 1, 3

Common symptoms at this stage include:

• Fatigue, irritability, and difficulty concentrating
• Exercise intolerance and dyspnea on exertion
• Restless legs syndrome (32-40% prevalence)
• Pica (40-50% prevalence)
• These symptoms can occur even when hemoglobin remains "normal" 1

Recommended Diagnostic Work-Up

Before starting treatment, the underlying cause must be identified:

1. Repeat Iron Studies Now

Your TSAT is 8 months old and should be remeasured alongside a complete iron panel:

• Serum iron, TIBC, transferrin saturation, and ferritin
• Complete blood count with red cell indices (MCV, MCH)
• C-reactive protein to assess for inflammation that might elevate ferritin 2, 4, 3

2. Identify the Source of Iron Loss

The most common causes of iron deficiency are:

• Gastrointestinal blood loss (94% of cases in adults): In men and postmenopausal women, bidirectional endoscopy (upper endoscopy and colonoscopy) is mandatory to exclude malignancy. 1, 3

• Menstrual blood loss: In premenopausal women, assess menstrual patterns. Heavy menstrual bleeding (≥4 days duration or excessive volume) is the leading cause. 1, 3

• Malabsorption: Test for celiac disease (tissue transglutaminase antibody) and Helicobacter pylori infection, both common and treatable causes. 3

• Dietary insufficiency: Assess iron intake, particularly in vegetarians/vegans or those with restricted diets. 1

• Medications: NSAIDs, aspirin, and anticoagulants increase gastrointestinal blood loss. 1

3. Screen for Chronic Inflammatory Conditions

If CRP is elevated, consider:

• Chronic kidney disease (check creatinine and eGFR)
• Heart failure (assess for symptoms, BNP if indicated)
• Inflammatory bowel disease (if gastrointestinal symptoms present)
• Malignancy (age-appropriate cancer screening) 1, 3

Treatment Algorithm

First-Line: Oral Iron Supplementation

For iron deficiency without inflammation and no contraindications to oral therapy:

• Ferrous sulfate 325 mg (65 mg elemental iron) every other day is the preferred regimen. Alternate-day dosing improves absorption and reduces gastrointestinal side effects compared to daily dosing. 1, 3

• Take on an empty stomach (1 hour before or 2 hours after meals) to maximize absorption. If gastrointestinal upset occurs, take with food despite reduced absorption. 3

• Avoid taking with calcium supplements, antacids, proton pump inhibitors, or tea/coffee, which impair absorption. 3

• Common side effects include constipation, nausea, and dark stools; approximately 50% of patients experience reduced adherence due to adverse effects. 3

Monitoring Response

• Recheck hemoglobin and iron studies (ferritin, TSAT) 8-10 weeks after starting oral iron. 4, 5

• Expected response: Hemoglobin should rise by 1-2 g/dL within 4-8 weeks, and ferritin should increase toward the target range. 4

• Target ferritin after repletion: ≥30-45 ng/mL with TSAT ≥20% in patients without chronic inflammation. 4

When to Use Intravenous Iron

Switch to IV iron if:

• Intolerance to oral iron (gastrointestinal side effects)
• Lack of response after 8-10 weeks of adequate oral therapy
• Malabsorption (celiac disease, post-bariatric surgery, atrophic gastritis)
• Ongoing blood loss that exceeds oral replacement capacity
• Chronic inflammatory conditions (CKD, heart failure, IBD, cancer) where hepcidin blocks intestinal iron absorption 2, 1, 3

IV iron formulations (ferric carboxymaltose, iron sucrose, low-molecular-weight iron dextran) bypass intestinal absorption and directly replenish stores. 2, 4

Common Pitfalls to Avoid

• Do not assume normal hemoglobin excludes clinically significant iron deficiency. Symptoms and progression to anemia occur as stores deplete further. 1, 3

• Do not rely on the 8-month-old TSAT value. Iron parameters change over time, and current values are needed to guide treatment. 4

• Do not skip the evaluation for underlying causes. Treating iron deficiency without identifying the source (especially occult malignancy) can delay critical diagnoses. 3

• Do not measure iron studies within 4 weeks of starting IV iron if that route is chosen, as circulating iron interferes with assays and produces falsely elevated results. 4

• Do not use daily oral iron dosing. Alternate-day dosing is superior for absorption and tolerability. 3