Low blood platelets may be due to lupus and other autoimmune diseases like rheumatoid arthritis.
Immune thrombocytopenia, aka idiopathic thrombocytopenic purpura (ITP), is another autoimmune disease in which the cause of low blood platelets may be unrelated to another condition (idiopathic).
According to one 2022 retrospective study, ITP may be a risk factor for developing lupus.