How should I evaluate and manage a patient with low hematocrit, low hemoglobin, elevated platelet count, and increased red cell distribution width?

Evaluation and Management of Low Hematocrit, Low Hemoglobin, High Platelets, and High RDW

This laboratory pattern strongly suggests iron deficiency anemia (IDA), and you should immediately obtain serum ferritin, transferrin saturation, and CRP to confirm the diagnosis, then proceed with comprehensive gastrointestinal evaluation to identify the source of blood loss. 1

Initial Diagnostic Workup

The combination of anemia with elevated RDW is highly characteristic of iron deficiency, as high RDW is an indicator of iron deficiency and reflects the heterogeneous red cell population that develops during iron-depleted erythropoiesis 1. The elevated platelet count further supports this diagnosis, as reactive thrombocytosis commonly accompanies chronic blood loss 2.

Essential Laboratory Tests

The minimum workup must include: 1

• Serum ferritin (the most powerful test for iron deficiency) 1
• Transferrin saturation 1
• CRP concentration (to assess for inflammation that may elevate ferritin) 1
• Reticulocyte count (to assess bone marrow response) 1
• MCV (mean corpuscular volume) 1

Interpreting Iron Studies

Serum ferritin <12 μg/dL is diagnostic of iron deficiency 1. However, ferritin is an acute-phase reactant and can be falsely elevated with inflammation, malignancy, or hepatic disease 1. In the presence of inflammation:

• Ferritin <30 μg/L indicates iron deficiency without inflammation 1
• Ferritin up to 100 μg/L may still be consistent with iron deficiency when inflammation is present 1
• Ferritin >100 μg/dL makes iron deficiency almost certainly not present 1

Transferrin saturation <30% supports the diagnosis of iron deficiency 1.

Critical Consideration: Combined Deficiencies

The elevated platelet count with high RDW raises an important diagnostic consideration. A platelet count/MCH ratio >12.00 suggests combined iron and vitamin B12 deficiency rather than isolated iron deficiency 2. This is clinically significant because:

• Combined deficiencies can mask each other (microcytosis from iron deficiency neutralized by macrocytosis from B12 deficiency) 1
• High RDW helps identify this situation when MCV appears normal 1

If the PLT/MCH ratio is >12.00, measure vitamin B12 and folate levels 2.

Gastrointestinal Evaluation

In adult men and postmenopausal women with confirmed IDA, gastrointestinal blood loss is the most common cause, and exclusion of gastrointestinal malignancy is of prime concern 1.

Mandatory Investigations

All patients with confirmed IDA should undergo both upper and lower GI tract examination unless there is a history of significant non-GI blood loss: 1

1. Upper GI endoscopy with small bowel biopsies 1

   • Expected to reveal a cause in 30-50% of patients 1
   • Small bowel biopsies must be obtained as 2-3% of patients with IDA have celiac disease 1

2. Colonoscopy or barium enema 1

   • Essential even if upper endoscopy reveals a lesion
   • Dual pathology (lesions in both upper and lower GI tracts) occurs in approximately 10% of cases 1

Common Causes to Consider

Most common sources of occult GI blood loss: 1

• Colonic cancer/polyps
• Gastric cancer
• Angiodysplasia
• NSAID use
• Inflammatory bowel disease (Crohn's disease, ulcerative colitis)
• Celiac disease (malabsorption)

Additional Testing if Initial Workup Negative

If H. pylori testing was not performed during initial endoscopy and IDA persists or recurs after normal upper and lower GI evaluation, test for H. pylori by non-invasive methods and eradicate if present 1.

Management

Iron Replacement Therapy

All patients should receive iron supplementation to correct anemia and replenish body stores: 1

• First-line: Ferrous sulfate 200 mg twice daily 1
• Continue for 3 months after iron deficiency is corrected to replenish stores 1
• Lower doses may be equally effective and better tolerated if standard dosing causes side effects 1

For Patients Intolerant or Not Responding to Oral Iron

Parenteral iron preparations are available: 1

• Iron sucrose (Venofer): 200 mg IV over 10 minutes
• Ferric carboxymaltose (Ferinject): up to 1000 mg IV over 15 minutes
• Iron dextran (Cosmofer): up to 20 mg/kg IV over 6 hours (can cause serious reactions in 0.6-0.7% of cases)

Critical Pitfalls to Avoid

• Do not assume dietary insufficiency as the sole cause without full GI investigation 1
• Do not stop investigation if NSAID use is identified—continue full evaluation 1
• Do not rely on faecal occult blood testing—it is insensitive and non-specific for IDA evaluation 1
• Do not miss celiac disease—always obtain small bowel biopsies during upper endoscopy 1
• Do not overlook combined vitamin B12 deficiency when platelets are markedly elevated 2