Perturbations in Serum Fructosamine Level in Diabetic Hyperthyroid Cats – a Retrospective Study

Gal A., Trusiano B., French A., et al.

Conference Proceedings, (2016). American College of Veterinary Internal Medicine, Denver:


Previous studies indicated that serum fructosamine level is decreased in hyperthyroid cats; however, its clinical utility in diabetic hyperthyroid cats was not reported. We hypothesized that hyperthyroidism in diabetic cats will result in a clinically significant decrease in serum fructosamine level compared to euthyroid diabetic cats. Data of serum total thyroxine (TT4) and fructosamine of hyperthyroid/euthyroid diabetic/nondiabetic cats from the New Zealand Veterinary Pathology and Colorado State University were retrieved and statistically analyzed. Serum fructosamine was significantly lower in hyperthyroid diabetic than euthyroid diabetic cats (mean 332 μmol/L 95% CI 291–379, n = 18 versus mean 527 μmol/L 95% CI 515–553, n = 186) while not different between hyperthyroid diabetic and euthyroid nondiabetic cats (mean 332 μmol/L 95% CI 291–379, n = 18 versus mean 321 μmol/L 95% CI 296–345, n = 128). There was a significant negative correlation between serum TT4 concentration and serum fructosamine and glucose concentrations (n = 659, p < 0.01, and n = 297, p < 0.01, respectively). Hyperthyroid cats (diabetic or not) had significantly (p < 0.05) lower serum glucose than euthyroid cats (diabetic or not). Diabetes and random variability accounted for 49.7% and 45.4% of the change in serum fructosamine; whereas, age (3.1%) and population (1.8%) had minimal impact on serum fructosamine. In conclusion, in the current study, serum fructosamine concentration was significantly decreased in diabetic hyperthyroid cats and was similar to the fructosamine concentration in euthyroid nondiabetic cats. In addition, approximately 45% of the change in serum fructosamine was independent of diabetes. Future studies should be undertaken to explore specific factors that have an impact on fructosamine level.