The Thyroid Peroxidase IgG test is a rapid ELISA method for the detection of IgG antibodies to human thyroid peroxidase. It is intended as an aid to diagnosis of autoimmune thyroid disease. The components of the kit are for in vitro diagnostic use only.
2. Explanation of the Test
Thyroid peroxidase (TPO) is the major enzyme involved in the multiple steps of thyroid hormone synthesis. Autoantibodies to TPO are associated with both Hashimoto's thyroiditis and Gravesâ€™ disease. The presence of anti-TPO autoantibodies unequivocally confirms autoimmune thyroiditis and they are frequently the presenting indication of underlying disease. The detection of anti-TPO autoantibodies is evidence against goitre or hypothyroidism of non-autoimmune nature.
The test is calibrated against the NIBSC standard 66/387.
3. Principle of the test
Diluted serum samples are incubated with TPO immobilised on microtitre wells. After washing away unbound serum components, rabbit anti-human IgG conjugated to horseradish peroxidase is added to the wells, and this binds to surface-bound antibodies in the second incubation. Unbound conjugate is removed by washing, and a solution containing 3,3â€™,5,5â€™-tetramethylbenzidine (TMB) and enzyme substrate is added to trace specific antibody binding. Addition of Stop Solution terminates the reaction and provides the appropriate pH for colour development. The optical densities of the standards, controls and samples are measured using a microplate reader at 450nm. Optical density is directly proportional to antibody activity in the sample.
Rapoport B and McLachlan SM. Thyroid peroxidase autoantibodies. In â€˜Autoantibodiesâ€™, JB Peter and Y Shoenfeld, eds.,Elsevier Science B.V., Amsterdam, The Netherlands, 1996, p816.
Prentice LM et al. Geographical distribution of subclinical autoimmune thyroid disease in Britain: a study using highly sensitive direct assays for autoantibodies to thyroglobulin and thyroid peroxidase. Acta Endocrinol 123: 493, 1990.
Kaufman KD et al. Generation of recombinant, enzymatically active human thyroid peroxidase and its recognition by antibodies in the sera of patients with Hashimotoâ€™s thyroiditis. J Clin Invest 84: 394, 1989.
Czarnocka B et al. Purification of the human thyroid peroxidase and identification as the microsomal antigen involved in autoimmune thyroid diseases. FEBS Lett 109:147, 1985.
Wall JR and Kuroki, T. Immunologic Factors and Thyroid disease. Medical Clinics of North America 69: 913, 1985.
Davies TF and DeBernado, E. Thyroid autoantibodies and disease. In â€˜Autoimmune Endocrine Diseaseâ€™, TF Davies, ed., Wiley, New York, NY, 1983, p127.
Gordin A, Maatela J, Miettinen A, et al; Serum thyrotrophin and circulating thyroglobulin and thyroid microsomal antibodies in a Finnish population. Acta Endocrinol (Copenh). 1979 Jan;90(1):33-42.
Vanderpump MP, Tunbridge WM, French JM, et al; The incidence of thyroid disorders in the community: a twenty-year follow-up of the Whickham Survey. Clin Endocrinol (Oxf). 1995 Jul;43(1):55-68. [abstract]
Lorini R, Gastaldi R, Traggiai C, et al; Hashimoto's Thyroiditis. Pediatr Endocrinol Rev. 2003 Dec;1 Suppl 2:205-11; discussion 211. [abstract]
Demirbilek H, Kandemir N, Gonc EN, et al; Hashimoto's thyroiditis in children and adolescents: a retrospective study on clinical, epidemiological and laboratory properties of the disease. J Pediatr Endocrinol Metab. 2007 Nov;20(11):1199-205. [abstract]
Amenduni T, Bellitti P, Carbone A, et al; Unusual association of Hashimoto's thyroiditis with autoimmune hepatitis. Thyroid. 2007 Dec;17(12):1307-8.
Alkhateeb A, Stetler GL, Old W, et al; Mapping of an autoimmunity susceptibility locus (AIS1) to chromosome 1p31.3-p32.2. Hum Mol Genet. 2002 Mar 15;11(6):661-7. [abstract]
Holm LE, Blomgren H, Lowhagen T; Cancer risks in patients with chronic lymphocytic thyroiditis. N Engl J Med. 1985 Mar 7;312(10):601-4. [abstract]
Larson SD, Jackson LN, Riall TS, et al; Increased incidence of well-differentiated thyroid cancer associated with Hashimoto thyroiditis and the role of the PI3k/Akt pathway. J Am Coll Surg. 2007 May;204(5):764-73; discussion 773-5. Epub 2007 Feb 23. [abstract]
Rosenbaum RL, Barzel US; Levothyroxine replacement dose for primary hypothyroidism decreases with age. Ann Intern Med. 1982 Jan;96(1):53-5. [abstract]
Odeke S. Hashimoto Thyroiditis. e-Medicine. May 2006.
OMIM. Hashimoto thyroiditis.
Merck Manual. Hashimoto's thyroiditis.
Thyroid manager: Chapter 8 - Hashimoto's thyroiditis. Last updated July 2007.