Pituitary Pars Intermedia Dysfunction (PPID) – Labordiagnostische Verlaufsuntersuchungen in einer Fall-Kontroll-Studie bei Pferden und Ponies
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Beschreibung
In a case-control study, clinical and laboratory diagnostic parameters were to be investigated in periods representative of the four seasons. PPID patients and the respective control horses should be of the same age and breed as far as possible and should be kept under management conditions that are as similar as possible. At each time, clinical examinations and blood sampling were carried out for extensive biochemical and laboratory diagnostic analyses. By means of a t-test, the age of the horses was compared. The statistical evaluation for differences between the groups (PPID vs. control) and between the four points in time was carried out by the two factor analysis of variance. Pairwise mean comparisons were carried out as a post-hoc test.
Over 19 months, a total of each 39 PPID patients and controls were sampled in the periods "Spring" (08.03.-27.04.), "Summer" (04.06.-03.08.), "Autumn" (04.09.-28.10.) and "Winter" (06.01.-27.01.). Nine PPID patients and 5 controls retired prematurely and were replaced by newly recruited horses. 23 patients received pergolide (0.5 mg/animal per day with one ex-ception receiving 2 mg) throughout the study period. Twelve patients started pergolide treat-ment during the study (also 0.5 mg/animal per day) and only four PPID patients remained without treatment. PPID patients had a significantly higher age (25.0 ± 6.6 years) than con-trols (20.2 ± 4.0 years). No significant differences were calculated in the Body Condition Score or in the biometrically determined body weight, but the PPID patients showed higher spans. From a laboratory diagnostic point of view, both groups experienced under- or ex-ceedances of the respective reference intervals in individual cases, whereby higher numbers of abnormal values were seen in the PPID patients. Statistically, these showed significantly higher levels in ACTH, insulin using RIA, glucose, triglycerides and potassium. The values of the base excess or erythrocyte counts were significant lower in the PPID patients. Partly contrary to previous information, no higher cortisol, fructosamine, γ-GT, GLDH, creatinine or urea levels were found in PPID patients in the case-control study. Between the seasons, ACTH, insulin using CLIA, glucose, urea, base excess, γ-GT, leukocytes and eosinophilic granulocytes were predominantly significantly different, with no statistically significant interactions between the two groups and the time points.
Despite the high rate of PPID patients treated with pergolide mesylate, their ACTH levels were higher than those of the healthy control horses and the further increase in ACTH in the autumn typical of this disease also occurred far away. Although it should be taken into ac-count that treatment effects may have reduced differences between the groups, a significant indicator of
PPID remained and thus the group comparison makes sense. Methodologically critical, it should also be noted that the PPID patients were older than the controls. Thus, differences between cases and controls could be age-related and not disease-related. To the author's knowledge, however, it has been possible for the first time to compare repeatedly assigned case-control pairs with a relatively small age difference and with otherwise very similar hus-bandry and management conditions.
For the first time, a number of routine laboratory parameters have also been shown to show significant differences between seasons – both in controls and in PPID patients. The extent to which it is necessary to create seasonally specific reference intervals is reserved for future projects. The study has further shown that PPID treatment with 0.5 mg of pergolide per horse per day is not sufficient to prevent the increased release of POMC products from the pars intermedia of the pituitary gland. PPID horses often show concomitant higher insulin levels with higher blood glucose and triglyceride concentrations than the controls. On the other hand, there was no evidence of increased cortisol levels or increased kidney or liver values in PPID patients. The leukocytes also did not differ from the controls.
Autor*in
Wencke Schwarz
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Adenom Cushing Krankheit Geriatrie Glukokortikoide Hyperplasie Hypophyse PPID Pallaske equines Cushing Syndrom