Abstract: The development of autoimmune diseases may be influenced by hormonal, immunomodulatory, and metabolic pathways. Prolactin (PRL), ferritin, vitamin D, and the tumor marker tissue polypeptide antigen (TPA) were measured in autoimmune diseases: systemic lupus erythematosus (SLE), systemic sclerosis (SSc), rheumatoid arthritis (RA), polymyositis (PM), dermatomyositis (DM), multiple sclerosis (MS), autoimmune thyroid diseases, and antiphospholipid syndrome. Hyperprolactinemia (HPRL) was detected in 24% of PM patients, in 21% of SLE patients, in 6.7% of MS patients, 6% of RA patients, and in 3% of SSc patients. Hyperferritinemia was detected in 23% of SLE patients, 15% of DM patients, 8% of MS patients, and 4% of RA patients. The patients had relatively low levels of 25 OH Vitamin D: the average results (mean ± SD) were between 9.3 ± 4.4 to 13.7 ± 7.1 ng/mL in the different diseases, while the 25 OH Vitamin D concentrations less than 20 ng/mL are regarded as deficient. TPA levels were in the same range of the controls, elevated only in SLE. HPRL, hyperferritinemia, hypovitaminosis D, and TPA levels did not correlate with SLE activity elevated levels of rheumatoid factor or anti-CCP antibodies in RA. HPRL, hyperferritinemia, and hypovitaminosis D have different immunological implications in the pathogenesis of the autoimmune diseases. Preventive treatment with vitamin D or therapy for HPRL with dopamine agonists, may be considered in certain cases. Hyperferritinemia may be used as an acute-phase reactant marker in autoimmune diseases mainly SLE. TPA may be used to indicate the tendency for malignancies.