Can Tuberculosis Cause Warm AIHA?
Yes, tuberculosis can cause warm autoimmune hemolytic anemia (AIHA), though it is a rare complication of TB infection. This association is well-documented in case reports and systematic reviews, with TB-induced AIHA representing an uncommon but recognized hematological manifestation of tuberculosis 1, 2.
Evidence for TB-Induced Warm AIHA
The connection between tuberculosis and warm AIHA is established through multiple case reports and systematic analyses:
- A systematic review of 21 published cases found that TB-induced AIHA presents with positive direct Coombs test in all patients, with mean hemoglobin of 5.77 g/dl 2
- Pulmonary tuberculosis was the most common form (43%) associated with AIHA, though disseminated TB also causes this complication 2
- Recent case reports confirm TB can trigger refractory AIHA requiring combination therapy 1, 3
Clinical Presentation
When TB causes warm AIHA, patients typically present with:
- Fever and pallor in more than half of cases 2
- Severe anemia (mean Hb ~5.8 g/dl) with positive direct antiglobulin test 2
- Constitutional symptoms that may overlap with TB itself (weight loss, fever) 4
Pathophysiologic Mechanism
TB induces autoimmune hemolysis through immune dysregulation, with IgG autoantibodies produced against red blood cells leading to extravascular hemolysis via antibody-dependent cellular cytotoxicity 5. The exact mechanism involves breakdown of immune tolerance triggered by chronic infection 6.
Treatment Approach
The management requires a three-pronged approach: anti-tuberculosis medications, corticosteroids, and blood transfusions as needed 2:
- All patients require standard anti-TB therapy as the primary treatment 2
- Corticosteroids are indicated, particularly in disseminated TB-induced AIHA (67% of cases required steroids versus only 13% in localized TB) 2
- Prednisone is FDA-approved for acquired (autoimmune) hemolytic anemia 7
- Rituximab may be added for refractory cases not responding to steroids and anti-TB treatment 1, 8
- Blood transfusions are used for severe symptomatic anemia 2
Important Clinical Considerations
Physicians should maintain high suspicion for TB as a cause of AIHA, especially in TB-endemic regions 2. The diagnosis requires:
- Positive direct antiglobulin test (DAT) to confirm AIHA 8
- Identification of active TB through appropriate microbiological and radiological studies 2
- Exclusion of other secondary causes of warm AIHA, particularly lymphoproliferative disorders like CLL 5
The hematologic complications typically improve with successful TB treatment, confirming the causal relationship 3. This distinguishes TB-induced AIHA from primary AIHA or other secondary causes that may not resolve with infection treatment alone.