ANA, antinuclear antibodies; fT4, free thyroxine; HLA-B27, human leukocyte antigen B27; IBD, inflammatory bowel disease; JIA, juvenile idiopathic arthritis; RF, rheumatoid factor; SD, standard deviation; TG, thyroglobulin; TPO, thyroid peroxidase; TSH, thyroid stimulating hormone. Here, TPO is linked to rheumatoid factor measurement.