Introduction Haematological involvement in Systemic Lupus Erythematosus (SLE) is common in patients with SLE. On the other hand, one of the most important variables that helps in disease activity and severity is complement serum level.

Objectives The aim of this study was to evaluate the relationship between haematological involvement in Systemic Lupus Erythematosus patients and hypocomplementemia.

Methods This is an observational study where 62 patients with SLE haematological involvement were included. All the patients were followed-up at UHC Mother Teresa, Tirana, Albania. All clinical and laboratory data were evaluated, gathered and analysed at our University clinic. It was evaluated especially the level of complement and the complete blood count in order to achieve the data needed for this study.

Results It was found that from 62 patients with SLE and haematological involvement, 11 patients were found with only one series affected (anaemia, leucopenia, thrombocytopenia), 10 patients were found with bicytopenia, and 41 were found with pancytopenia. After evaluating the complement levels, hypocomplementemia was found in 2 patients (18.2%) from the first group, in 8 patients (80%) from the second group, and 38 patients (92.6%) from the third group.

Conclusion From our study was found that there is a directly proportional relationship between hypocomplementemia and the severity of haematological involvement in SLE patients.

The more severe it is the haematological involvement, the more affected seem to be the complement serum levels.