Plasma fructosamine concentrations in horses with pituitary pars intermedia dysfunction with and without laminitis

Reasons for performing study: Plasma fructosamine concentration ([fructosamine]) is believed to reflect medium term, average blood glucose concentration and in a previous study was higher in horses with active laminitis than in normal horses. Pituitary pars intermedia dysfunction (PPID) is associated with hyperglycaemia and laminitis. Objectives: To test the hypotheses that: [fructosamine] is higher in PPID cases than normal animals; furthermore, that within cases of PPID [fructosamine] is higher in those with active laminitis than nonlaminitic cases and in cases that have been affected by active laminitis in the preceding year than those that have not. Study design: Observational, case-control/cross-sectional study. Methods: [Fructosamine] was measured in cases of PPID (n = 46) and normal animals (n = 139). A normal range was calculated; values were compared between the 2 groups and within the PPID group, between cases with and without active laminitis and between cases that had and had not been affected by active laminitis in the preceding year. Results: In normal animals mean [fructosamine] was 248.7 mu mol/l; the normal range (mean +/- 2 s.d.) was 195.5-301.9 mu mol/l. Plasma [fructosamine] was not higher in PPID cases than in normal animals. In PPID cases, [fructosamine] was significantly (P = 0.006) higher in cases with active laminitis (mean +/- s.d. 261.2 +/- 39.2 mu mol/l) compared with those without active laminitis (234.5 +/- 32.9 mu mol/), but [fructosamine] was not higher in cases that had been affected by active laminitis in the preceding year than those that had not. Conclusions: In horses affected by PPID, [fructosamine] is higher in cases with active laminitis than in cases without active laminitis. Potential relevance: Clinical use of [fructosamine] is limited due to overlap with the normal range. Further studies into glucose and protein metabolism in cases of PPID are warranted. The Summary is available in Chinese - see Supporting information.