Special Precautions/Comments:

Method: ELISA. Calibration: Manufacturer derived standard. EQA scheme: UK NEQAS scheme for Diabetic Markers. IQC: Commercial preparation and kit controls

Interferences: Serum samples which are haemolysed, icteric or hyperlipaemic should ideally not be used. If such samples are analysed, appropriate comments must be made on the worksheet and reported as a report comment at the time of result entry. Specimens containing visible particulate matter should be clarified by centrifugation prior to use

Interpretation: Results >15 U/mL may be indicative of type 1 diabetes. The test should be used in conjunction with the other diabetic markers – GAD65 antibodies, IA-2 antibodies and islet cell antibodies

Additional Information:

Indication: Type 1 diabetes.

 

Background Information: Zinc transporter 8 (ZnT8) is an islet beta cell secretory granule membrane protein that has been identified as an autoantibodies antigen in type 1 diabetes. ZnT8 antibodies can be used in addition to the other diabetic markers: GAD65 antibodies, IA-2 antibodies and Islet cell antibodies to differentiate clinical phenotypes.

Positive GAD65 antibodies, IA-2 antibodies and ZnT8 antibodies in combination are associated with younger age of onset of autoimmune diabetes and more severe insulin deficiency. ZnT8 antibodies can be seen in up to 80% of new type 1 diabetes cases and in up to 26% of type 1 diabetes patients that are negative for GAD65 antibodies, IA-2 antibodies, islet cell antibodies and insulin antibodies. The antibodies generally appear later than GAD65 antibodies and Insulin antibodies, although not in a strict order. The combined measurement of ZnT8 antibodies, GAD65 antibodies, IA-2 antibodies and insulin antibodies raised the detection rate to 98% at disease onset

References:

Lampasona V, et al. Zinc transporter 8 antibodies complement GAD and IA-2 antibodies in the identification and characterisation of adult-onset autoimmune diabetes. Diabetes Care, 2010, 33: 104-8. Vaziri-Sani F, et al. ZnT8 autoantibody titres in type 1 diabetes patient decline rapidly after clinical onset. Autoimmunity. 2010, 43:598-606. Wenzlau J, et al. The cation efflux transporter ZnT8 (scl30A8) is a major autoantigen in human type 1 diabetes. PNAS. 2007, 104:17040-45. Lampasona V, et al. Diabetes antibody standardisation program: first proficiency evaluation of assays for autoantibodies to zinc transporter 8. Clin Chem. 2011, 57:1693-1702. Tiberti C, et al. Detection of four diabetes specific autoantibodies in a single radioimmunoassay: an innovative high-throughput approach for autoimmune diabetes screening. CEI. 2011. 166: 317-324. NICE Guideline 17 (NG17). Type 1 diabetes in adults: diagnosis and management. Published 2015, updated July 2016. NICE Guideline 18 (NG18). Diabetes (type 1 and type 2) in children and young people: diagnosis and management. Published 2015, updated November 2016

See Also: GAD65, IA-2 antibodies, Islet cell antibodies

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