Porcine thyroglobulin was important in the discovery of alpha-Gal allergy. Here, the linkage of porcine thyroglobulin-specific IgE with IgE positivity to routinely assessed allergens and to the incoming diagnosis within a population of suspected atopic individuals is explored. IgE, IgA, total IgG and IgG subclasses to porcine thyroglobulin, IgE to bovine, human thyroglobulin and meat extract were measured with ELISA. The following correlations were observed in IgE binding to porcine and bovine thyroglobulin (r = 0.910, p = 1x10 ^-17 ), porcine and human thyroglobulin (r = 0.635, p = 4x10 ^-6 ), human and bovine thyroglobulin (r = 0.746, p = 6x10 ^-9 ) and porcine thyroglobulin and meat extract (r = 0.482, p = 0.0009). Only one out of ten samples which showed binding to porcine thyroglobulin in ELISA tested positive with ImmunoCAP alpha-Gal, implying different epitope/s. Increased IgE binding was detected towards a more electronegative fraction of porcine thyroglobulin separated according to charge and the binding could be partially inhibited by galactose. Anti-thyroglobulin IgE was found in 29.7% of the population, in subjects who were significantly younger, p < 0.0001 and it occurred more frequently in patients referred for testing penicillin specific IgE (OR 2.48, p = 0.0059) and were negative. IgE specific to porcine, bovine and possibly human thyroglobulin may be implicated in post-infectious skin manifestation misinterpreted as penicillin allergy.