Patient description: A 16-year-old girl came to the clinic complaining of weight gain and abnormal menstrual cycles. Her BMI was 24, but she has gained 5 kg in the past few weeks. She gets tired more frequently and does not have energy to go dancing with her friends. Her lab results were remarkable for high TSH levels (15 mU/L) and low free T4 levels (0.18 ng/dl). Her anti-TPO levels were extremely high (136 IU/ml). She was diagnosed with Hashimoto disease. She does not smoke and she is not sexually active.

Clinical trial eligibility criteria: eligible ages (years): 0.0-999.0,  Rheumatoid Arthritis Healthy General: Healthy women, or women with RA, 18-55 year old, with a history of regular menses or who are perimenopausal, have a BMI less than 30, able to provide informed consent to all aspects of the study after full information is provided. Women must have a negative pregnancy test at screening. Study participants will be allowed to continue taking medications for chronic, stable conditions, such as hypertension and hypercholesteremia, while in the study for RA Patients: Active RA as defined by 9 tender and 6 swollen joints; ESR greater than 35 mm/hr OR CRP greater than 2.0 mg/dL; and, morning stiffness greater than 45 min. Actively menstruating with a normal estrogen level or who are perimenopausal. Women must be practicing, or willing to practice, an acceptable method of birth control that does not involve use of prescription or OTC estrogen/progesterone preparations during the two weeks prior to screening. Acceptable means of contraception abstinence, barrier methods with spermicides, intrauterine devices (IUD's) or surgical sterilization. (phase 2 of the study only) Current use of nonsteroidal anti-inflammatory drugs (NSAIDs) and/or hydroxychloroquine are permitted. Drug doses must have been stable for at least one month prior to enrollment, and must be held constant during the study unless toxicity requires dose reduction. Past use of a disease modifying agent (DMARD) such as methotrexate, sulfasalazine and cyclosporine is allowed  General: Patients or control subject will be excluded if they exhibit any medical condition that has the potential of placing the candidate at unnecessary risk during the study. Additionally, patients with impaired renal, hepatic, cardiovascular or endocrine-metabolic function, or any immunodeficiency syndrome including HIV infection, will be excluded Use of systemic corticosteroids in the two weeks before screening and study entry. Women with a history of cancer, with the exception of limited, resolved skin cancer. Women who are menopausal. Clinical menopause is defined as the absence of spontaneous menses during the preceding 12 months. Pregnant women or women who are nursing. Use of prescription or OTC estrogen/progesterone preparations during the two weeks prior to screening The patient or control subject has received any investigational drug within 30 days of the start of the study. History of autoimmune endocrinopathy. Serious medical illnesses or abnormal laboratory values that would, in the opinion of the P.I., preclude study participation For RA Patients: BMI greater than or equal to 30. Active infection or other contraindication to use of an anti-TNF agent (phase 2 of the study only). History of untreated tuberculosis, or of a positive PPD without completion of adequate treatment. (phase 2 of the study only) Live vaccinations in the 3 months prior to study (phase 2 of the study only)