How to manage a patient with low hemoglobin?

Management of Low Hemoglobin

The management of low hemoglobin requires a systematic diagnostic approach followed by targeted treatment based on the underlying cause, with iron supplementation being first-line therapy for iron deficiency anemia, which is the most common cause of low hemoglobin. 1

Diagnosis of Anemia

Definition and Thresholds

• Anemia is defined as hemoglobin concentration <13.5 g/dL in adult males and <12.0 g/dL in adult females 2
• These thresholds should trigger further evaluation regardless of symptoms

Initial Laboratory Workup

1. Core diagnostic tests:

   • Complete blood count with peripheral smear
   • Reticulocyte count
   • Iron studies (serum ferritin, transferrin saturation)
   • Inflammatory markers (ESR, CRP)
   • Lactate dehydrogenase, haptoglobin, bilirubin (if hemolysis suspected)

2. Classification based on MCV:

   Parameter	Iron Deficiency	Thalassemia Trait	Anemia of Chronic Disease
   MCV	Low	Very low (<70 fl)	Low/Normal
   RDW	High (>14%)	Normal (≤14%)	Normal/Slightly elevated
   Ferritin	Low (<30 μg/L)	Normal	Normal/High
   TSAT	Low (<16%)	Normal	Low
   RBC count	Normal/Low	Normal/High	Normal/Low

Special Considerations for Diagnosis

• In inflammatory states, ferritin (an acute phase reactant) may be falsely elevated
• With inflammation present, consider iron deficiency when ferritin is 30-100 μg/L with transferrin saturation <16% 2
• Anemia of chronic disease is likely if ferritin >100 μg/L and transferrin saturation <16% 2

Treatment Approach

Iron Deficiency Anemia

1. Oral iron therapy:

   • First-line treatment: 35-65 mg elemental iron daily 1
   • Continue for 3 months after hemoglobin normalizes to replenish stores
   • Common options: ferrous sulfate, ferrous fumarate, ferrous gluconate

2. Parenteral iron:

   • Consider when oral iron is ineffective, not tolerated, or rapid repletion needed
   • Options include iron sucrose, ferric carboxymaltose, iron dextran
   • Indicated when ferritin <100 μg/dL and transferrin saturation <20% 2

Anemia of Chronic Disease

1. Treat underlying condition (primary approach)
2. Consider erythropoietin therapy for selected cases:
   • Recommended for anemia in chronic kidney disease
   • Starting dose: 50-100 Units/kg three times weekly 3
   • Monitor hemoglobin weekly after initiation and dose adjustments
   • Reduce dose if hemoglobin increases >1 g/dL in any 2-week period

Transfusion Therapy

1. Asymptomatic patients:

   • Restrictive approach with hemoglobin threshold <7 g/dL 2
   • Target maintenance hemoglobin 7-9 g/dL

2. Symptomatic patients:

   • Consider transfusion for hemoglobin <8-10 g/dL with symptoms
   • Symptoms include tachycardia, tachypnea, postural hypotension
   • Higher threshold (10 g/dL) for acute coronary syndromes 2

Monitoring

• Hemoglobin levels should be measured at least annually in all patients with chronic kidney disease 2
• More frequent monitoring (every 3-6 months) for patients with:
  • Greater disease burden
  • Unstable clinical course
  • Evidence of previous hemoglobin decline 2
• For patients treated for iron deficiency, check hemoglobin after 2-4 weeks of therapy to assess response

Common Pitfalls to Avoid

1. Inadequate investigation: Don't accept anemia without thorough investigation, especially in elderly patients 1
2. Overlooking functional iron deficiency: Patients may have functional iron deficiency despite normal ferritin in inflammatory states 1
3. Insufficient treatment duration: Continue iron therapy for 3 months after hemoglobin normalizes 1
4. Ignoring coexisting deficiencies: Check for vitamin B12 and folate deficiency in macrocytic or persistent anemia 1
5. Inappropriate erythropoietin use: Avoid targeting hemoglobin >12 g/dL with erythropoietin therapy due to increased cardiovascular risks 3

Special Population Considerations

• Chronic kidney disease: Anemia develops consistently when GFR <60 mL/min/1.73 m² (stage 3 CKD) and prevalence increases with CKD progression 2
• Diabetes: Anemia is more prevalent, more severe, and occurs earlier in the course of CKD in diabetic patients 2
• Elderly: Lower hemoglobin levels in older males should not be considered normal without excluding pathological causes 2
• Liver disease: Patients on triple therapy for hepatitis C have high risk of anemia requiring dose adjustments 2

By following this systematic approach to diagnosis and treatment, most cases of anemia can be effectively managed with significant improvements in patient quality of life, morbidity, and mortality.