IgG antibody precipitin testing from serum is useful, as positive results are found in between 69 and 90% of patients, though also in 10% of asthmatics with and without SAFS. Therefore, it must be used in conjunction with other tests. Various forms exist, including enzyme-linked immunosorbent assay (ELISA) and fluorescent enzyme immunoassay (FEIA). Both are more sensitive than conventional counterimmunoelectrophoresis. IgG may not be entirely specific for ABPA, as high levels are also found in chronic pulmonary aspergillosis (CPA) alongside more severe radiological findings.