What is the appropriate diagnostic workup and first‑line treatment for a patient presenting with haemolytic anemia?

Diagnostic Workup and First-Line Treatment for Hemolytic Anemia

Begin with immediate laboratory testing including CBC with reticulocyte count, peripheral blood smear, LDH, haptoglobin, indirect bilirubin, and direct antiglobulin test (DAT/Coombs), as these markers confirm hemolysis and guide treatment decisions. 1, 2

Initial Diagnostic Workup

Essential First-Line Laboratory Tests

• Complete blood count (CBC) with red cell indices to assess anemia severity and red cell characteristics 1, 3
• Reticulocyte count >3-5% indicates appropriate bone marrow response to hemolysis 1, 2
• Peripheral blood smear examination for schistocytes, spherocytes, or other morphologic abnormalities 3, 2, 4
• Lactate dehydrogenase (LDH) is markedly elevated due to release from lysed red cells 1, 2
• Haptoglobin is decreased or undetectable as it binds free hemoglobin 1, 2
• Unconjugated (indirect) bilirubin is elevated, typically <5 mg/dL in chronic hemolysis 1, 2
• Direct antiglobulin test (DAT/Coombs) differentiates immune from non-immune causes 3, 2, 5

Critical Specialized Testing Based on Clinical Presentation

If schistocytes are present or thrombotic microangiopathy (TMA) is suspected:

• ADAMTS13 activity level and inhibitor titer must be ordered urgently to distinguish TTP from other TMAs 6, 1
• ADAMTS13 <10% is diagnostic of TTP and requires immediate plasma exchange 6, 1
• Platelet count, creatinine, and urinalysis for hematuria/proteinuria to assess for TMA triad 6
• Complement testing (C3, C4, CH50) for suspected atypical hemolytic uremic syndrome (aHUS) 6

Do not delay plasma exchange while awaiting ADAMTS13 results if TTP is strongly suspected clinically, as mortality increases with delayed treatment. 6

For DAT-positive (immune) hemolysis:

• Perform both direct and indirect antiglobulin testing 3, 5
• Evaluate for underlying autoimmune conditions, lymphoproliferative disorders, or drug exposure 7, 3

For DAT-negative (non-immune) hemolysis:

• Glucose-6-phosphate dehydrogenase (G6PD) levels to exclude enzymopathies 3, 2
• Hemoglobin electrophoresis if hemoglobinopathy suspected 2, 4
• Paroxysmal nocturnal hemoglobinuria (PNH) screening by flow cytometry 3
• Consider genetic testing for hereditary membranopathies or enzymopathies if family history or chronic course 4

Additional Workup Considerations

• Review medication history thoroughly, as drugs cause hemolysis through multiple mechanisms 3, 2
• Viral and bacterial studies if infection-related hemolysis suspected 3
• Reject visibly hemolyzed blood samples as they cause spurious results in >60% of cases 1

First-Line Treatment Algorithm

Grade 1 (Mild): Hemoglobin 10 g/dL or higher with minimal symptoms

• Hold any potentially causative medications and monitor closely 6, 3
• Folic acid supplementation 1 mg daily for all patients with hemolysis 3
• Hematology consultation recommended 6

Grade 2 (Moderate): Hemoglobin 8-10 g/dL with moderate symptoms

For autoimmune hemolytic anemia (AIHA):

• Oral prednisone 0.5-1 mg/kg/day as first-line therapy 3, 7
• Expected response rate of 70-80% in warm AIHA 3
• Monitor hemoglobin levels weekly during steroid tapering 3
• Folic acid 1 mg daily 3

For TMA with ADAMTS13 >10% (aHUS):

• Prednisone 0.5-1 mg/kg/day and close monitoring 6
• Hematology consultation urgently 6

Grade 3 (Severe): Hemoglobin <8 g/dL or symptomatic

For autoimmune hemolytic anemia:

• Intravenous methylprednisolone 1-2 mg/kg/day as first-line treatment 3, 7
• Consider hospital admission based on clinical status 3
• RBC transfusion only if symptomatic or hemoglobin <7-8 g/dL in stable, non-cardiac patients 6, 3
• Do not transfuse more than the minimum necessary 6

If no response to corticosteroids within 1-2 weeks:

• Add intravenous immunoglobulin (IVIG) 0.4-1 g/kg/day for 3-5 days 3

For delayed hemolytic transfusion reaction with hyperhemolysis (especially in sickle cell disease):

• High-dose steroids and IVIG as first-line treatment 6, 3
• Use extended antigen-matched red cells (C/c, E/e, K, Jk^a^/Jk^b^, Fy^a^/Fy^b^, S/s) if transfusion required 6
• Avoid routine transfusion as it may worsen hyperhemolysis 6

Grade 4 (Life-Threatening): Hemodynamic instability or severe organ dysfunction

For TTP (ADAMTS13 <10%):

• Immediately initiate therapeutic plasma exchange (PEX) without waiting for ADAMTS13 results if clinically suspected 6, 1
• Methylprednisolone 1 g IV daily for 3 days, with first dose given immediately after first plasma exchange 6
• Continue daily plasma exchange until platelet count exceeds 100-150 × 10⁹/L for 2 consecutive days 6
• Platelet transfusion is contraindicated unless life-threatening bleeding 6

For aHUS with clinical consequences:

• Begin eculizumab therapy urgently: 900 mg weekly for four doses, 1,200 mg week 5, then 1,200 mg every 2 weeks 6
• Administer meningococcal vaccination and long-term penicillin prophylaxis 6

Monitoring During Acute Phase

• Daily CBC with differential, LDH, haptoglobin, and creatinine during acute hemolysis 1
• Serial bilirubin measurements within 2-3 hours if total serum bilirubin ≥25 mg/dL or rapidly rising 1
• Monitor for steroid-related complications: hyperglycemia, hypertension, mood changes, insomnia, fluid retention 3

Refractory or Relapsing Disease

For hemolytic anemia not responding to first-line therapy:

• Rituximab 375 mg/m² weekly for 4 weeks as second-line option 3, 7
• Consider immunosuppressive agents: cyclosporine, mycophenolate mofetil, or azathioprine 3, 7
• Cyclophosphamide may be considered in severe refractory cases 3

Taper steroids gradually over at least 4-5 weeks once improvement to Grade ≤1 is achieved 3

Critical Pitfalls to Avoid

• Do not dismiss TMA based on "rare" schistocytes alone, as low schistocyte counts can occur in early or evolving TMA 6
• The absence of abundant schistocytes does not exclude TMA due to low test sensitivity 6
• Delaying treatment in severe cases increases morbidity and mortality 3
• IV anti-D should be used with caution as it can exacerbate hemolysis in patients with AIHA 3
• High-dose IVIG carries nephrotoxic risk in patients with cast nephropathy; prefer corticosteroids in this setting 3
• Splenectomy is not indicated in hereditary stomatocytosis and may be harmful; confirm diagnosis before considering splenectomy 7

Special Considerations

For cancer-related hemolysis:

• Evaluate for autoimmune hemolytic anemia in chronic lymphocytic leukemia or erythrophagocytosis in histiocytic tumors 7
• Consider microangiopathic processes and hypersplenism in myeloproliferative neoplasms 7

For malignant hypertension-associated TMA:

• Initiate controlled blood pressure lowering; TMA typically improves within 24-48 hours 6
• This presentation shows only moderate thrombocytopenia and few schistocytes compared to TTP/HUS 6