What is the diagnosis and treatment for a patient with mild anemia, elevated RDW, abnormal neutrophil and lymphocyte percentages, and elevated AST levels?

Diagnostic Interpretation and Management

Based on your laboratory values showing mild anemia (MCHC 30.8 g/dL), markedly elevated RDW (17.5%), lymphocyte predominance (54.2%), relative neutropenia (31.5%), and mildly elevated AST (40), you most likely have iron deficiency anemia with concurrent viral infection or chronic inflammatory process, and you require immediate serum ferritin testing, transferrin saturation, and CRP to confirm iron deficiency before initiating treatment. 1, 2

Key Laboratory Findings Analysis

Anemia Pattern

• Elevated RDW (17.5%) is pathognomonic for iron deficiency anemia when combined with low MCHC, as this reflects heterogeneous red cell populations from progressive iron depletion 1, 2
• The markedly elevated RDW (>14.0%) essentially excludes thalassemia trait, which typically presents with normal or only slightly elevated RDW 1, 2
• High RDW strongly distinguishes iron deficiency from anemia of chronic disease, making iron deficiency the primary diagnostic consideration 3

White Blood Cell Pattern

• Lymphocyte predominance (54.2%) with relative neutropenia (31.5%) suggests viral infection or early recovery phase rather than bacterial infection 3
• This pattern may also indicate chronic inflammatory conditions including inflammatory bowel disease, which commonly presents with iron deficiency anemia 3

Liver Function

• Mildly elevated AST (40) may reflect hepatic congestion from anemia, viral hepatitis, or inflammatory bowel disease-related hepatic involvement 3

Immediate Diagnostic Workup Required

Essential First-Line Tests

• Serum ferritin is the single most powerful test and must be obtained immediately to confirm iron deficiency 1, 2
  • Ferritin <30 μg/L confirms iron deficiency in absence of inflammation 3
  • Ferritin <100 μg/L may still indicate iron deficiency if concurrent inflammation is present 3
• Transferrin saturation <30% supports iron deficiency and should be measured 1, 2
• C-reactive protein (CRP) is necessary to interpret ferritin correctly in the context of inflammation 3, 1

Additional Workup

• Complete reticulocyte count to assess bone marrow response—low or normal reticulocytes indicate deficiency states rather than hemolysis 3
• Vitamin B12 and folate levels, as combined deficiencies can present with elevated RDW even when MCV appears normal 1, 2
• Haptoglobin and lactate dehydrogenase if reticulocytes are elevated to exclude hemolysis 3
• Hepatitis panel given elevated AST and lymphocyte predominance 3

Gastrointestinal Investigation Protocol

All adult men and post-menopausal women with confirmed iron deficiency require complete gastrointestinal evaluation, regardless of symptom presence or severity of anemia. 2

Mandatory Endoscopic Evaluation

• Upper endoscopy with mandatory small bowel biopsies to exclude malignancy and detect celiac disease (present in 2-3% of IDA patients) 2
• Colonoscopy or CT colonography to exclude colonic cancer and polyps 2
• Even mild anemia warrants investigation, as severity does not correlate with likelihood of serious underlying disease 1, 2

Common GI Sources to Investigate

• NSAID use, colonic cancer/polyps, gastric cancer, angiodysplasia 2
• Celiac disease, Crohn's disease, ulcerative colitis 3, 2
• Continuous blood loss from ulcerated bowel surfaces in inflammatory bowel disease 3

Treatment Algorithm

If Iron Deficiency Confirmed (Ferritin <30 μg/L or <100 μg/L with inflammation)

• Initiate oral iron supplementation immediately once iron deficiency is confirmed 1, 2
• Continue treatment for 3-6 months after hemoglobin normalizes to replete iron stores 2
• Stop NSAIDs and anticoagulants whenever possible 2
• Address any identified GI pathology 2

If Vitamin B12 or Folate Deficiency Identified

• Vitamin B12 deficiency: 100 mcg intramuscular daily for 6-7 days, then alternate days for seven doses, then every 3-4 days for 2-3 weeks, followed by 100 mcg monthly for life 4
• Folic acid should be administered concomitantly if needed 4

If Inflammatory Bowel Disease Suspected

• Iron supplementation is recommended when iron deficiency anemia is present 3
• Treat underlying intestinal inflammation as this triggers both blood loss and anemia of chronic disease 3

Critical Pitfalls to Avoid

• Never assume iron deficiency based solely on anemia—elevated RDW makes iron deficiency highly likely, but ferritin testing is mandatory for confirmation 1, 2
• Do not empirically treat with iron without confirming iron deficiency, as this can cause iron overload in thalassemia patients (though your elevated RDW makes thalassemia very unlikely) 1
• Do not overlook combined deficiencies (iron plus B12 or folate), which may coexist and require simultaneous treatment 1, 2
• Do not attribute lymphocytosis solely to viral infection without excluding inflammatory bowel disease or other chronic inflammatory conditions 3
• Do not delay gastrointestinal investigation in adult men or post-menopausal women, as malignancy must be excluded 2