What is the initial treatment for an adult outpatient with low hemoglobin (anemia) and no significant medical history?

Initial Treatment for Outpatient Low Hemoglobin in Adults

For an adult outpatient with newly diagnosed anemia and no significant medical history, begin oral iron supplementation with ferrous sulfate 200 mg three times daily after confirming iron deficiency, while simultaneously investigating the underlying cause through appropriate diagnostic workup. 1, 2

Immediate Diagnostic Priorities Before Treatment

Before initiating any therapy, confirm iron deficiency through laboratory testing:

• Measure serum ferritin as the single most useful marker – values <30 ng/mL strongly suggest iron deficiency 1
• Check transferrin saturation (TSAT <20% supports iron deficiency) 1, 2
• Review peripheral blood smear for microcytic, hypochromic red cells 1, 2
• A hemoglobin rise ≥10 g/L within 2 weeks of iron therapy confirms absolute iron deficiency, even if initial iron studies were equivocal 1

Essential Workup to Identify Underlying Cause

All adults with unexplained anemia require investigation for the source, as approximately one-third of men and postmenopausal women have underlying pathology, most commonly gastrointestinal 1:

• Perform urinalysis or urine microscopy to exclude occult blood loss 1
• Screen for celiac disease with tissue transglutaminase (tTG) antibody, as 3-5% of iron deficiency anemia cases are due to celiac disease 1, 3
• Check vitamin B12 and folate levels 1, 2
• Obtain detailed menstrual history in premenopausal women 3, 4
• In men and postmenopausal women, bidirectional endoscopy (gastroscopy and colonoscopy) should be first-line GI investigation 1

First-Line Treatment: Oral Iron Supplementation

Initiate ferrous sulfate 200 mg orally three times daily 2, 3, 4:

• Continue therapy for 3 months after hemoglobin correction to replenish iron stores 2, 3
• Monitor hemoglobin weekly until stable, then monthly 2, 5
• Expect hemoglobin rise of approximately 1 g/dL every 2-3 weeks with adequate response 1

When to Consider Intravenous Iron Instead

Intravenous iron should be considered first-line in specific circumstances 1:

• Severe anemia requiring rapid correction
• Intolerance to oral iron (gastrointestinal side effects)
• Malabsorption conditions (inflammatory bowel disease, celiac disease)
• Inadequate response to oral iron after 4-6 weeks

Red Blood Cell Transfusion Thresholds

Transfuse only when hemoglobin falls below 7.0 g/dL in hemodynamically stable patients without extenuating circumstances 1, 2:

• Higher thresholds (8-10 g/dL) apply for patients with active myocardial ischemia, severe hypoxemia, or acute hemorrhage 1
• Use the minimum number of units necessary to relieve symptoms 2, 3
• Transfusion does not replace the need for iron supplementation to replenish stores 1

When NOT to Use Erythropoiesis-Stimulating Agents (ESAs)

ESAs have no role in routine outpatient iron deficiency anemia without specific indications 1, 2:

• Do not initiate ESAs when hemoglobin is >10 g/dL due to increased thromboembolic risk 1, 2, 5
• ESAs are reserved for chemotherapy-induced anemia or chronic kidney disease with specific criteria 1, 5
• ESAs increase mortality and cardiovascular events when targeting hemoglobin >13 g/dL 1, 2
• Never use erythropoietin for general anemia treatment in outpatients 1

Critical Pitfalls to Avoid

Failure to identify the underlying cause leads to recurrent anemia and missed diagnoses 1, 3:

• Never assume menstruation alone explains severe anemia in premenopausal women without excluding GI pathology 1
• In men and postmenopausal women, unexplained iron deficiency anemia warrants urgent GI evaluation for malignancy 1
• Do not continue iron supplementation beyond 3-4 months without reassessing if hemoglobin fails to normalize 1, 2
• Recheck iron studies if inadequate response to therapy, as this suggests ongoing blood loss, malabsorption, or alternative diagnosis 1, 2

Monitoring Treatment Response

Track response systematically 2, 5:

• Hemoglobin should be monitored weekly until stable, then at least monthly 1, 5
• Reassess iron status (ferritin, TSAT) after 3 months of therapy 2
• Continue monitoring for at least one year after normalization to detect recurrence 2
• If hemoglobin has not increased by >1 g/dL after 4 weeks of adequate iron therapy, investigate for ongoing blood loss, malabsorption, or alternative diagnosis 1, 5