Systemic lupus erythematosus (SLE) is an autoimmune disease with higher prevalence in
women than men, with a female-to-male ratio ranging from 8:1 to 15:1.SLE is characterized
by periods of remission and exacerbation (flares) with prolonged periods of subclinical
activity, thus making it a very unpredictable disease needs continuous assessment of disease
activity. There is no single biomarker used for that purpose. Platelet activation markers as
CD62p and Platelet indices have recently been found to be a simple inflammatory marker
used in the assessment of systemic inflammation in many diseases like rheumatoid arthritis,
ankylosing spondylitis and, inflammatory bowel diseases. Aim of study, to investigate the
platelet indices and their relation to platelet activation and disease activity in SLE patients. A
case-control study enrolled forty SLE recruited from AL-Zahraa University Hospital Al-
Azhar University. According to Systemic Lupus Erythematosus Disease Activity Index
(SLEDAI) score the patients were divided into three groups first one including ten patients
without flare (SELEDAI <4), a second group including ten patients moderate flare
(SELEDAI 8 – <12) and the third group including twenty patients with severe flare
(SELEDAI >or=12). Another forty persons apparently healthy including in the study as a
control group. P selectin and Platelet indices (MPV, PDW, PTC) were assessed in all of them
and their correlation to the SLEDAI score was analyzed. There was a highly significant
increase in P selectin in the active patients more than non-active patients (p-value < 0.05)
and a highly significant increase in severe activity compared to moderate activity (p-value <
0.001), and a significant decrease in PCT and MPV in the active patients less than non-
active patients (p-value < 0.05) and it is decreased in severe cases compared to moderate
activity, non-active and control groups(p-value < 0.05 ) and it had a significant negative
correlation with SELEDAI score. By Using the ROC curve, it was shown that MPV can be
used to discriminate between active & non-active SLE patients with a specificity of 66.7%
and sensitivity 60%. Also, CD62p can be used to discriminate between active & non-active
SLE patients with 66.7% sensitivity & 80% specificity. P selectin, mean platelet volume
(MPV), and Plateletcrit (PCT) could be used as a novel marker for SLE activity.