An assessment of the CITE T4 immunoassay
Eckersall, P.D.; McEwan, N.A.; Mooney, C.
Veterinary Record 129(24): 532-533
1991
ISSN/ISBN: 0042-4900 PMID: 1788920 Document Number: 368753
The SEMI-QUANT CITE T4 (IDEXX, High Wycombe) test kit which uses the technology of a dot immunofiltration staining assay and provides a semiquantative estimate of T4 concentration was compared to the established radioimmunnoassay. (RIA) to determine whether it could identify hypothyroid dogs and hyperthyroid. The T4 concentration in serum was classified as hypothyroid (<13 nmol/litre) euthyroid (13 to 48 nmol/litre) or hyperthyroid (>48 nmol/litre). For the diagnosis of feline hyperthyroidism the kit gave 100% agreement with the RIA results i.e. 10 hyperthyroid cats (T4 = 13 to 65 nmol/litre by RIA) had T4 concentration > 48 nmol/litre, and euthyroid cats (T4 = >70 nmol/litre by RIA) 13 to 48 nmol/litre by the use of the CITE kit. The results for the canine samples revealed that for 8 samples from dogs considered to be hypothyroid on the basis of T4 identified by RIA (< 13 nmol/litre), the CITE assay also gave a concentration of <13 nmol/litre for the 9 dogs considered to be euthyroid (T4 of 30 to 56 nmol/litre with RIA), the CITE T4 was shown to be within the reference range 13-48 nmol/litre. For the 12 dogs considered not to have a clear diagnosis as hypothyroid on the basis of RIA i.e. with a T4 concentration in the normal range (T4 between 13 and 30 nmol/litre) the CITE T4 indicated that 4 samples had a T4 of < 13 nmol/litre and 8 had T4 samples of 13-48 nmol/litre. The CITE T4 kit was rapid (20 minutes), simple to perform and required no extra equipment and provided that the complication of hypothyroid dogs with T4 concentrations in the normal range was considered in the interpretation of the test kit should be of benefit in the rapid diagnosis of these endocrine diseases.