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Zinc Transporter 8 (ZnT8) Antibody

Test code(s) 93022

Question 1. What is the primary clinical use of the ZnT8 antibody test?

This test is mainly used to assist in the diagnosis of type 1 diabetes mellitus. For this purpose, it can be used alone or in combination with other antibody tests such as the glutamic acid decarboxylase-65 (GAD-65), insulinoma antigen-2 (IA-2), and insulin antibody tests.

Question 2. Which individuals may be suitable for ZnT8 antibody testing?

ZnT8 antibody testing can be considered for:

  • Individuals with diabetes of uncertain etiology
    • Young person with atypical diabetes
    • Person with ketosis-prone diabetes that is not clearly type 1
    • Person suspected of having maturity-onset diabetes of the young (MODY)
    • Woman with gestational diabetes (help clarify risk of future diabetes)
  • Obese individuals with acute-onset diabetes with ketoacidosis
  • Lean individuals with nonketotic diabetes
  • Individuals at high risk of developing type 1 diabetes (eg, those with a first-degree relative with type 1 diabetes) in context of a clinical research study1

Question 3. How frequently are ZnT8 antibodies detected in patients with type 1 diabetes mellitus?

Sixty-five percent to 80% of children with recently diagnosed type 1 diabetes2,3 and 20% to 40% of adults with type 1 diabetes3,4 have antibodies to ZnT8.

Question 4. To what degree does the ZnT8 antibody test complement other more commonly used autoantibody tests?

The ZnT8 antibody can add 3% to 4% to the antibody sensitivity for type 1 diabetes. This is because ZnT8 antibody is positive in 3% to 4% of patients who are negative for GAD-65, IA-2, and insulin antibodies.2,5,6 Use of these 4 antibodies results in 93% to 98% sensitivity.2,5,6

Question 5. Are there other clinical uses of the ZnT8 antibody test?

ZnT8 antibody testing may help to assess the risk of type 1 diabetes. Achenbach et al found that almost half of children with ZnT8 antibody developed type 1 diabetes within 5 years.7 Moreover, since risk of type 1 diabetes increases with the number of antibodies, a positive ZnT8 antibody test can reclassify individuals into a higher risk category.

Question 6. How early can ZnT8 antibodies be detected in patients?

ZnT8 antibodies can be detected as early as 9 months of age but are more common after 2 years.2,7 Antibody titers decrease over the course of the disease, and patients who are initially ZnT8 antibody-positive may later become antibody- negative.3,5,8

 

References
 
  1. American Diabetes Association. Classification and diagnosis of diabetes. Diabetes Care. 2015;38(suppl 1):S8-S16.
  2. Andersson C, Vaziri-Sani F, Delli AJ, et al. Triple specificity of ZnT8 autoantibodies in relationship to HLA and other islet autoantibodies in childhood and adolescent type 1 diabetes. Pediatr Diabetes. 2013;14:97-105.
  3. Vaziri-Sani F, Oak S, Radtke J, et al. ZnT8 autoantibody titers in type 1 diabetes patients decline rapidly after clinical onset. Autoimmunity. 2010;43:598-606.
  4. Kawasaki E, Nakamura K, Kuriya G, et al. Differences in humoral autoreactivity to zinc transporter 8 between childhood- and adult-onset type 1 diabetes in Japanese patients. Clin Immunol. 2011;138:146-153.
  5. Petruzelkova L, Ananieva-Jordanova R, Vcelakova J, et al. The dynamic changes of zinc transporter 8 autoantibodies in Czech children from the onset of type 1 diabetes mellitus. Diabet Med. 2014;31:165-171.
  6. Wenzlau JM, Moua O, Sarkar SA, et al. SLC30A8 is a major target of humoral autoimmunity in type 1 diabetes and a predictive marker in prediabetes. Ann NY Acad Sci. 2008;1150:256-259.
  7. Achenbach P, Lampasona V, Landherr U, et al. Autoantibodies to zinc transporter 8 and SLC30A8 genotype stratify type 1 diabetes risk. Diabetologia. 2009;52:1881-1888.
  8. Wenzlau JM, Walter M, Gardner TJ, et al. Kinetics of the post-onset decline in zinc transporter 8 autoantibodies in type 1 diabetic human subjects. J Clin Endocrinol Metab. 2010;95:4712-4719.
This FAQ is provided for informational purposes only and is not intended as medical advice. A physician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.
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Effective 06/24/2015 to present