Purpose Thrombocytopenia is one of the most common hematological manifestations of SLE and some studies reveal, that this manifestation can be associated with specific organ involvement and higher disease activity. The aim of this study is to indicate differences between SLE patients with and without thrombocytopenia and also to find connections between the severity of thrombocytopenia and the titer of SLE specific antibodies.

Methods 61 patients with a mean age of 32 ± 6.1years and with 8.1 ± 4.7 years’ duration of SLE were enrolled in this study. All patients fulfilled with the EULAR/ACR 2019 classification criteria. Disease activity was measured with help of SLEDAI-2K score. ANA, Anti-dsDNA, Anti-Sm, APL antibodies, ESR, CRP were evaluated. Thrombocytopenia was graded as mild (100000–150000/μl), moderate(50000–100000/μl) and severe (<50000/μl).

Results 85,25% of examined patients were females and 14,75% males. Thrombocytopenia was seen in 25 patients (40,98%) at any period of the disease. 36 patients without thrombocytopenia were included in the control group. 16 patients (26,23%) presented with mild thrombocytopenia, 6 (9,836%)with moderate and only 3 (4,92%) with severe. Due to the study patients with thrombocytopenia have significantly higher levels of SLEDAI-2k, ESR and CRP compared to the control group (p<0,05). 72% of patients with thrombocytopenia had any of APL antibodies and significant correlation between the titer of anticardiolipin antibodies and thrombocytopenia severity was found (p=0,001). On the other hand, no significant difference between the level of anti-dsDNA and anti-Sm antibodies between the groups was found. Associations between the severity of thrombocytopenia and the titer of anti-dsDNA and anti-Sm antibodies were also not detected. Patient with thrombocytopenia 2,33 times frequent presented with any type of neurological manifestations of SLE compared with non-thrombocytopenic once and 1,33 times more with any type of Lupus nephritis and 3,66 - with livedo reticularis (p<0.05).

Conclusion As concluded from our study, thrombocytopenia is associated with higher disease activity and is connected with more severe organ damage. Taking this into consideration thrombocytopenia could be implemented in clinical practice as a predictor for SLE progression. More investigations with bigger samples are needed to find out, if there are any differences between groups connected with other manifestations and thrombocytopenia.