Diagnosis: Iron Deficiency Anemia with Compensated Erythrocytosis
This patient has iron deficiency anemia (IDA) causing hypochromic microcytic red blood cells, with a compensatory erythrocytosis (elevated RBC count) attempting to maintain adequate oxygen delivery, and a reactive monocytosis that is likely secondary to chronic inflammation or the underlying iron deficiency state.
Laboratory Analysis
Iron Deficiency Pattern
- MCH 25.5 pg (low) and MCHC 31.0 g/dL (low) confirm hypochromia, indicating insufficient hemoglobin concentration in red blood cells 1
- The combination of low MCH and low MCHC with normal MCV (82.2 fL) represents early or evolving iron deficiency 2
- Hypochromic red blood cells (hemoglobin concentration <28 g/dL) are the hallmark of iron-deficient erythropoiesis 3
- The microcytic-hypochromic pattern with these indices strongly suggests iron deficiency rather than thalassemia trait 2
Erythrocytosis Component
- RBC count 5.84 million/uL (elevated) with normal hemoglobin 14.9 g/dL and hematocrit 48.0% indicates compensated erythrocytosis 4
- This represents the body's physiologic attempt to increase oxygen-carrying capacity by producing more red blood cells, despite each cell carrying less hemoglobin 4
- The elevated RBC count prevents anemia from becoming symptomatic despite iron deficiency 5
Monocytosis
- Absolute monocytes 1350 cells/uL (elevated, reference 200-950) represents mild monocytosis
- This is commonly seen as a reactive process in chronic iron deficiency states 4
Diagnostic Workup Required
Immediately obtain serum ferritin, iron, TIBC, and transferrin saturation (TSAT) to confirm iron deficiency and assess severity 1:
- Ferritin <45 μg/L confirms iron deficiency 1
- Low serum iron with elevated TIBC and low TSAT (<20%) confirms the diagnosis 1, 6
Evaluate for underlying cause of iron deficiency:
- Assess for gastrointestinal blood loss (most common in adults) 6
- In menstruating women, evaluate menstrual blood loss 6
- Consider malabsorption syndromes if dietary intake is adequate 6
Treatment Algorithm
First-Line Oral Iron Therapy
Initiate ferrous sulfate 324 mg (65 mg elemental iron) one to three times daily 1:
- Take on empty stomach with vitamin C (ascorbic acid) to enhance absorption 1
- If gastrointestinal side effects occur, switch to ferrous gluconate or ferrous fumarate 1
- Continue for at least 3 months after hemoglobin normalizes to replenish iron stores 1
Monitoring Response
Check hemoglobin and complete blood count at 2 weeks 1:
- Expected hemoglobin rise ≥1 g/dL (≥10 g/L) within 2 weeks confirms iron deficiency diagnosis 1
- Hemoglobin should increase at least 2 g/dL within 4 weeks 1
- Recheck at 4 weeks, 3 months, then every 3 months for first year 1
If Oral Iron Fails
Consider intravenous iron if:
- No hemoglobin response after 4 weeks of adequate oral therapy
- Malabsorption documented
- Intolerable gastrointestinal side effects despite formulation changes 6
Critical Pitfalls to Avoid
Do NOT perform phlebotomy despite the elevated RBC count and hematocrit 4:
- This is compensated erythrocytosis, NOT polycythemia vera
- Phlebotomy would worsen iron deficiency and increase stroke risk 4
- Routine phlebotomy is contraindicated and harmful in this setting 4
Do NOT assume this is cyanotic heart disease erythrocytosis without evidence of hypoxemia:
- Cyanotic heart disease causes erythrocytosis with hypoxemia and right-to-left shunting 4
- This patient has normal hemoglobin and no mention of cyanosis or cardiac disease
- The erythrocytosis here is compensatory for iron deficiency, not hypoxemia 4
Do NOT overlook iron deficiency in the presence of elevated RBC count:
- Iron deficiency can coexist with erythrocytosis 4
- The hypochromic indices (low MCH, low MCHC) are diagnostic regardless of RBC count 2, 3
- Iron deficiency with erythrocytosis increases stroke and thrombotic risk if untreated 4
Expected Outcomes
With appropriate oral iron therapy: