Serum thyroid autoantibodies in patients with idiopathic either acute or chronic urticaria.

In Italy, only one study was conducted on the detection of serum thyroid autoantibodies (ATA) in patients with urticaria. This northern-Italy study reported a 23% rate of ATA positiveness in 52 patients with chronic idiopathic urticaria (CIU). During the years 1998-2006, 688 patients with urticaria were hospitalized at our Division of Allergy and Clinical Immunology. Thyroglobulin and thyroperoxidase autoantibodies (TgAb and TPOAb) were assayed at admission in 144/688 patients. Of the 144 patients (mean age: 42.3+/-15.8 yr, range 17-84), 95 (72 women and 23 men) had an history of CIU (CIU group) and 49 (44 women and 5 men) did not [acute urticaria group or (AU)]. Of the 144 patients, 37 (25.7%) tested positive for at least one ATA: 31 with CIU (32.6%) and 6 with AU (12.2%, chi2=7.037, p=0.008). Positiveness for TPOAb or TgAb was 30/37 (81.1%) or 17/37 (45.9%); 10/37 (27.0%). Pre-hospitalization duration of CIU was longer in the 31 ATA positive patients compared to the 64 ATA negative patients (207.2+/-273.4 vs 81.6+/-106.3 weeks, p=0.015). Pre-hospitalization duration of CIU correlated positively with the log10-transformed serum concentration of TPOAb in the 25 CIU patients who tested TPOAb positive (r=0.42, p=0.039). We conclude that our rate of 31/95 (32.6%) positiveness for at least one type of ATA in CIU is greater than that of 6 representative international studies published between the years 2000 and 2006 (111/488 or 22.7%, range 15-29%, chi2=4.884, p=0.027).