Thyroid Disorder-Related Immune Thrombocytopenia: Clinical and Laboratory Characteristics

Thyroid disorders have been associated with immune thrombocytopenia. However, there is little published data regarding the clinical and laboratory manifestations of patients with hyper- and hypothyroidism-related thrombocytopenia (Th-ITP) compared with those with euthyroid chronic immune thrombocytopenia (E-ITP). We reviewed the medical records for 135 patients who fulfilled American Society of Hematology criteria for chronic ITP.

Results: Of the 135 patients, 71 (52.6%) were screened for thyroid disorders. Of these 71 patients, 17 (23.9%) were diagnosed with thyroid disorders, including 5 (29.4%) with overt hyperthyroidism, 5 (29.4%) with subclinical hyperthyroidism, 4 (23.5%) with overt hypothyroidism, and 3 (17.6%) with subclinical hypothyroidism. Four patients were diagnosed with thyroid disorders prior to their diagnosis of immune thrombocytopenia while 13 were diagnosed after. The duration of ITP follow-up was similar for the E-ITP (46.1 mo; range: 1– 333 mo) and Th-ITP patients (50.5 mo; range: 1– 173 mo). Age (49.9 yrs for Th-ITP vs. 45.9 for E-ITP), gender (82.3% females for Th-ITP vs. 70.3% for E-ITP), initial platelet counts (17.27 × 10⁹/L for Th-ITP vs. 18.87 × 10⁹/L for E-ITP), and initial bleeding manifestations (64.7% for Th-ITP vs. 66% for E-ITP) were not significantly different between the two groups. Significantly fewer Th-ITP than E-ITP patients had platelet counts <50k at diagnosis (76.5% vs. 85.6%, p = 0.021). There was a trend for Th-ITP to have platelet counts <50k at the end of follow-up (23.5% vs. 8.5%, p = 0.064), despite having a similar duration of follow-up and receiving a similar numbers of individual therapies (2.82 vs. 3.13). However, fewer Th-ITP patients underwent splenectomy (17.65% vs. 38.98%, p = 0.087). Lupus anticoagulant and anti-cardiolipin antibodies were more common in Th-ITP than E-ITP patients, although this difference was not statistically significant (40% vs. 26.2%; p=0.086).

Conclusions: Thyroid disorders are commonly observed in patients with immune thrombocytopenia, but do not appear to significantly affect the response to therapy or long-term outcome in ITP patients.