Can Chronic Psoriasis Cause Anemia and Thrombocytopenia?
Chronic psoriasis itself does not directly cause anemia or thrombocytopenia, but the systemic medications used to treat it—particularly immunosuppressive agents like azathioprine, leflunomide, and anti-TNF biologics—can cause these hematologic complications. 1
Hematologic Effects of Psoriasis Treatment
Immunosuppressive Medications
Azathioprine carries increased risk of hematologic toxicity and requires monthly complete blood count (CBC) monitoring for the first 6 months, then every 6-8 weeks thereafter. 1 This agent can cause pancytopenia, agranulocytosis, and thrombocytopenia, particularly in patients who have recently discontinued methotrexate or other immunosuppressive agents. 1
Leflunomide has rare reports of pancytopenia, agranulocytosis, and thrombocytopenia, most commonly occurring within the first 6 months of therapy and in patients with multiple risk factors for hematotoxicity. 1 Monthly CBC with differential is required for the first 6 months, then every 6-8 weeks thereafter. 1
Biologic Therapies and Platelet Changes
Anti-TNF agents (adalimumab, infliximab) cause platelet count reductions of approximately 17-18% during therapy, while ustekinumab causes 14.8% reduction and secukinumab causes 18.5% reduction. 2 These decreases correlate with disease activity improvement rather than representing true drug toxicity in most cases. 2
Drug-induced thrombocytopenia occurs in approximately 4.3% of patients receiving anti-TNF-alpha agents, with platelet counts recovering after drug suspension and relapsing upon re-exposure. 3 However, severe thrombocytopenia (platelet count <50×10⁹ cells/L) is rare, occurring in less than 1% of treated patients. 4
Critical Clinical Context
Patients with pre-existing liver disease (particularly alcoholic cirrhosis) face substantially higher risk of clinically significant thrombocytopenia when treated with biologics, potentially leading to subcutaneous hematomas and bleeding complications. 2 In these high-risk patients, careful platelet monitoring is essential throughout biologic therapy. 2
Tofacitinib may affect blood counts, with 0.04% of patients experiencing absolute lymphocyte counts below 500 cells/mm³ after 3 months of exposure, correlating with increased infection risk. 1
Psoriasis Disease Activity and Thrombosis Risk
Chronic skin-specific inflammation in psoriasis promotes a prothrombotic state rather than thrombocytopenia. 5 Psoriasis patients demonstrate platelet hyperactivity and deranged hemostatic balance favoring thrombosis, which may contribute to increased cardiovascular disease risk. 6, 5
The chronic inflammatory nature of psoriasis itself represents an independent cardiovascular risk factor, with systemic inflammation promoting endothelial dysfunction and atherosclerosis. 1
Monitoring Recommendations
Baseline CBC with differential is required before initiating azathioprine, leflunomide, or tofacitinib, followed by monthly monitoring for the first 6 months, then every 6-8 weeks thereafter. 1
For biologic therapies, regular CBC monitoring should be performed, particularly in patients with:
- Chronic liver disease 2
- History of autoimmune conditions 3
- Concurrent use of other immunosuppressive medications 1
Immediate platelet count assessment is warranted if autoimmunity is suspected or if patients develop unexplained bruising, petechiae, or bleeding. 3
Key Clinical Pitfalls
The most common error is attributing thrombocytopenia to psoriasis disease activity when it actually represents medication toxicity. 2 Conversely, mild platelet decreases during biologic therapy often reflect disease improvement rather than drug toxicity and do not require treatment discontinuation unless counts fall below 100×10⁹ cells/L. 2
Never assume that elevated platelet counts in psoriasis patients represent disease severity alone—thrombocytosis may persist independently of skin disease activity and resolve only with specific anti-inflammatory treatments like anti-TNF agents. 6