Overview

Autoimmune Hemolytic Anemia (AIHA) is a rare blood disorder in which the immune system mistakenly attacks and destroys the body's own red blood cells (RBCs), leading to anemia. The destruction of RBCs occurs faster than the body can produce new ones, causing a deficiency in healthy red blood cells. AIHA can range from mild to severe and may occur suddenly or develop gradually. It is classified into two main types: warm AIHA (caused by warm-reacting antibodies) and cold AIHA (caused by cold-reacting antibodies). Prompt diagnosis and treatment are important to prevent complications like severe anemia, jaundice, or organ damage.

Causes

AIHA can be either primary (idiopathic, with no identifiable cause) or secondary (associated with other conditions or triggers). Common causes include:

• Primary AIHA: The most common type, where the exact cause remains unknown, but the immune system produces antibodies against RBCs without an obvious trigger.
• Autoimmune Diseases: Conditions like systemic lupus erythematosus (SLE) or rheumatoid arthritis are frequently associated with AIHA.
• Infections: Viral infections such as Epstein-Barr virus, cytomegalovirus (CMV), HIV, and Mycoplasma pneumoniae may trigger AIHA.
• Cancers: Certain blood cancers like chronic lymphocytic leukemia (CLL) and lymphomas are linked with AIHA.
• Medications: Drugs like penicillin, methyldopa, or certain antibiotics can induce immune responses against RBCs.
• Cold Exposure: In cold AIHA, exposure to cold temperatures may trigger hemolysis by cold agglutinin antibodies.

Symptoms

Symptoms of AIHA vary depending on the rate of red blood cell destruction and the severity of anemia. Common signs and symptoms include:

• Fatigue: General weakness and lack of energy due to reduced oxygen-carrying capacity.
• Pale Skin: Pallor caused by anemia.
• Jaundice: Yellowing of the skin and eyes due to the breakdown of red blood cells releasing bilirubin.
• Shortness of Breath: Especially during physical activity, due to insufficient oxygen transport.
• Dark-Colored Urine: Due to hemoglobin released from destroyed red blood cells.
• Rapid Heart Rate (Tachycardia): Heart beats faster to compensate for reduced oxygen levels.
• Cold Sensitivity (in cold AIHA): Fingers, toes, ears may turn pale or blue in cold environments.

Diagnosis

Diagnosing AIHA involves a combination of clinical evaluation and laboratory testing to confirm hemolysis and identify autoimmune activity:

• Medical History and Physical Exam: Assessment of symptoms, history of autoimmune disease, infections, or medications.
• Complete Blood Count (CBC): Shows anemia, reduced hemoglobin, and increased reticulocyte count (young RBCs).
• Peripheral Blood Smear: May show fragmented RBCs and spherocytes (small, round red cells).
• Lactate Dehydrogenase (LDH): Elevated due to red cell destruction.
• Indirect and Direct Bilirubin: Increased levels due to RBC breakdown.
• Haptoglobin: Decreased as it binds free hemoglobin released from destroyed RBCs.
• Direct Antiglobulin Test (DAT or Coombs Test): The key diagnostic test, which detects antibodies or complement proteins attached to red blood cells, confirming autoimmune activity.

Treatment

Treatment of AIHA focuses on halting red blood cell destruction, treating underlying causes, and relieving symptoms:

First-Line Treatments

• Corticosteroids: Prednisone is usually the first-line treatment to suppress immune activity and reduce hemolysis.

Second-Line Treatments

• Immunosuppressive Drugs: Medications like azathioprine, rituximab, or cyclophosphamide may be used if steroids are ineffective or to minimize steroid side effects.
• Splenectomy: Surgical removal of the spleen may be considered in steroid-resistant cases since the spleen is a major site of RBC destruction.

Supportive Care

• Blood Transfusions: Administered in cases of severe anemia, though they are used cautiously due to risk of further immune reaction.
• Folic Acid Supplementation: Supports red blood cell production.
• Avoidance of Cold (for cold AIHA): To reduce hemolysis in cold agglutinin disease.

Prognosis

The prognosis of autoimmune hemolytic anemia varies depending on the type and underlying cause:

• Warm AIHA: Many patients respond well to corticosteroids, though relapses can occur. Long-term management may be needed in some cases.
• Cold AIHA: Often chronic but manageable with lifestyle modifications and medication.
• Secondary AIHA: Prognosis depends on successful treatment of the underlying condition (e.g., infection or cancer).
• Overall Outlook: With prompt diagnosis and appropriate treatment, many individuals can manage AIHA effectively, though some may require long-term therapy and monitoring to prevent relapses or complications.

Regular follow-ups with a hematologist are crucial to monitor disease activity and treatment response.