الفهرس 
Acknowledgement
Conditions associated with decreased prolactin level HypoprolactinaemiaOnly 14 pages are availabe for public view
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Abstract
Prolactin acts as a hormone due to pituitary secretion and as a cytokine due to extra pituitary production. As a hormone; PRL is secreted from the anterior pituitary gland, while as a cytokine; it’s synthesized in extra-pituitary sites including cells in the immune system.
PRL receptors are distributed throughout the immune system and it has an important role in the innate and adaptive immune response, by regulating the maturation of CD4- CD8- thymocytes to CD4+ CD8+ T cells via IL-2 receptor expression. There is a correlation between PRL level and the number of B and CD4+ T lymphocyte, PRL has immune modulatory effects by interfering with B cell tolerance induction, inhibiting apoptosis, enhancing antigen presentation, up regulating cytokine production and increasing antibody secretion.
Hyperprolactinemia (HPRL) was observed in some autoimmune rheumatic diseases.
In systemic lupus erythematosus (SLE), hyperprolactinemia was observed in SLE patients of both genders and was associated with disease activity in many studies. However, some studies did not support this association. The role of prolactin in the pathogenesis of SLE is not yet conclusive.
In systemic sclerosis (SSc), a possible association with disease duration and disease severity was found in some studies, while others deny this assosciation.
Psoriasis vulgaris, PRL plays a vital role in keratinocytes proliferation and is involved in the pathogenesis of psoriasis via its effect on the immune system; Therefore, serum PRL levels may serve as biomarker for psoriatic disease activity.
Rheumatoid arthritis (RA), the risk for developing RA is increased postpartum and it seems that breast-feeding is associated with an increased risk of rheumatoid arthritis, particularly after the first pregnancy. PRL may play a role in disease severity and the process of joint damage in RA and contributes to the development of the disease; however the association between HPRL and RA is inconsistent yet.
In behçet’s disease (BD), PRL levels have been shown to be significantly higher in patients and levels are associated with disease activity and most severe cases . On the other hand, some researchers have found that mean PRL levels in patients with clinically active BD were not significantly higher than in patients with clinically inactive BD and healthy controls.
In sjogren’s syndrome (SS), abnormal level and relative ratio of homone may play a role in the pathogenesis.Young SS patients with active disease had high prevalence of HPRL associated with internal organ disease, but there was no correlation with disease duration, serum immune globulins, autoantibodies, or focus score in minor salivary gland biopsy.
The conflicting results about the correlation between the disease activity and the concentration of serum PRL might be due to several potential causes such as heterogeneity of the groups of patients studied, different indices used to measure the disease activity, variable assays used for PRL measurement and lack of statistical power. On the other hand, PRL may not be a crucial factor in determining the disease activity. Through our study we found that the most observed clinical correlation with high serum PRL was found in patients with systemic lupus erythematosus and also in psoriatic patients .
But we believe that future in-depth research should identify these differences as being significant or non significant.