What is the management plan for a patient with a normal ferritin level and elevated platelet count?

Management of Normal Ferritin (119 ng/mL) with Elevated Platelet Count

A ferritin of 119 ng/mL is within normal range and requires no intervention for iron status; however, the elevated platelet count warrants investigation for underlying iron deficiency that may not yet be reflected in ferritin levels, particularly if transferrin saturation is low or if there are other signs of iron depletion.

Initial Assessment

The key is to determine whether this represents true iron sufficiency or functional iron deficiency masked by ferritin's role as an acute phase reactant:

• Measure transferrin saturation (TS) immediately - A TS <20% suggests functional iron deficiency despite normal ferritin, particularly in chronic disease states 1
• Check complete blood count parameters - Elevated platelets (>400 × 10⁹/L constitutes thrombocytosis) commonly occur with iron deficiency even when ferritin appears normal 2, 3
• Assess for inflammatory conditions - Ferritin >100 ng/mL can mask true iron deficiency when acting as an acute phase reactant 1

Clinical Context Matters

If Transferrin Saturation is <45% and Ferritin is Normal:

• No further evaluation needed for hemochromatosis - This combination effectively excludes HFE-related iron overload 1
• Consider iron deficiency if platelets are elevated - Iron-depleted patients have higher platelet counts (mean difference ~20,000/µL) compared to those with adequate stores 3

If Platelets are >400 × 10⁹/L (Thrombocytosis):

Investigate for occult iron deficiency:

• Thrombocytosis occurs in approximately 22% of patients with iron deficiency anemia at baseline 2
• Iron-depleted blood donors show 4.4% prevalence of thrombocytosis versus 2.0% in those with normal ferritin 3
• Check soluble transferrin receptor (sTfR) if available - sTfR >5 mg/dL or sTfR/log ferritin ratio <1.5 indicates functional iron deficiency 1

Management Algorithm

For Normal Ferritin (119 ng/mL) with Elevated Platelets:

1. If TS <20% or sTfR elevated:

   • Consider trial of iron supplementation
   • Oral iron 100-200 mg elemental iron daily or intravenous iron based on clinical urgency 2, 4
   • Recheck platelet count at 3 months - expect normalization if iron deficiency was causative 2, 4

2. If TS ≥20% and no evidence of iron deficiency:

   • Investigate alternative causes of thrombocytosis (myeloproliferative disorders, inflammation, malignancy, infection)
   • Ferritin 119 ng/mL with normal TS effectively excludes iron-related causes 1

3. Monitor response to iron if given:

   • Platelet counts decrease by average 19,800/µL in iron-depleted patients within 3 months 3
   • Thrombocytosis resolves in 95% of cases (from 22% to 5% prevalence) after iron replacement 2
   • Normalization of elevated platelets confirms iron deficiency was the cause 4

Common Pitfalls to Avoid

• Don't assume normal ferritin excludes iron deficiency - Ferritin between 100-200 ng/mL can represent functional deficiency in inflammatory states 1
• Don't ignore elevated platelets - This may be the only clue to iron depletion when ferritin is borderline normal 2, 3
• Don't check for hemochromatosis - A ferritin of 119 ng/mL with normal TS (<45%) has 97% negative predictive value for iron overload in patients <35 years 1

Specific Monitoring Parameters

If iron supplementation is initiated based on low TS or elevated platelets:

• Hemoglobin and platelet count at 3 months 2, 4
• Serum ferritin - target 50-100 ng/mL for maintenance if deficiency confirmed 1
• Transferrin saturation - should normalize to >20% with adequate replacement 1

The platelet count serves as a functional marker of iron status and should normalize within 3 months if iron deficiency was present, even when baseline ferritin appeared normal 2, 3, 4.