ABSTRACT
The GAD65 and IA-2 antibodies (Abs) are biomarkers of the development of type 1 diabetes mellitus (T1DM) in both children and adults. The upper reference limit for the autoantibodies made by the manufacture was established on an adult Chinese population. Here, we established upper reference limits for Northern European adults and children in accordance with the Clinical and Laboratory Standards Institute (CLSI) guidelines. Serum samples from healthy Danish children (0-18 years) and adults (18-70 years) were analysed for GAD65Ab and IA-2Ab using MAGLUMI 800 Chemiluminescence Immunoassay (CLIA). The Kruskal-Wallis test was used for evaluating differences between gender and age groups. No gender or age differences were found for neither GAD65Ab nor IA-2Ab, and a combined upper reference limit for both children and adults could be established. An upper reference limit of 5.1 IU/mL was defined for GAD65Ab and 11.5 U/mL for IA-2Ab. Our results showed a substantial discrepancy with the reference limits established by the manufacturer.
Subject(s)
Autoantibodies/blood , Glutamate Decarboxylase/antagonists & inhibitors , Immunoassay/standards , Receptor-Like Protein Tyrosine Phosphatases, Class 8/antagonists & inhibitors , Adolescent , Adult , Aged , Biomarkers/blood , Child , Child, Preschool , Diabetes Mellitus, Type 1/blood , Diabetes Mellitus, Type 1/diagnosis , Diabetes Mellitus, Type 1/ethnology , Diabetes Mellitus, Type 1/immunology , Europe , Female , Gene Expression , Glutamate Decarboxylase/genetics , Glutamate Decarboxylase/immunology , Healthy Volunteers , Humans , Infant , Infant, Newborn , Luminescence , Male , Middle Aged , Receptor-Like Protein Tyrosine Phosphatases, Class 8/genetics , Receptor-Like Protein Tyrosine Phosphatases, Class 8/immunology , Reference Values , White PeopleABSTRACT
BACKGROUND AND AIMS: Chromogranin A (CgA) is the most important general tumour marker used in the diagnosis and follow-up of patients with neuroendocrine tumours (NET). Chromogranin A assays may have different sensitivities, which is of importance for the clinical diagnosis and handling of NET patients. The aim of this study was to compare the clinical sensitivities of three different CgA assays in NET patients. METHODS: We measured CgA level in 42 NET patients (male/female: 23/19, median age: 63 years, range 29-85 years). Twenty-five patients had liver metastases, eight had local disease, and nine were disease free after surgery. We studied an in-house RIA: RH RIA assay (Rigshospitalet, Copenhagen, Denmark); NEOLISATM (Euro Diagnostica, Malmö, Sweden) and EURIA CgA RIA (Euro Diagnostica, Malmö, Sweden). RESULTS: The RH RIA assay showed a clinical sensitivity of 97%, while the NEOLISA and EURIA assays both showed similar clinical sensitivities of 79%. Patients with liver metastases had significantly higher CgA levels compared to disease free patients by all three assays (P<0.001), but only the RH RIA assay was able to discriminate between patients with liver metastases and with regional disease (P<0.01). CONCLUSION: Chromogranin A measurements are significantly assay-dependent and caution should be applied in the interpretation of CgA measurement for assessment of NET status. The in-house RH RIA assay was better at predicting NET status than the NEOLISA and EURIA assays.
