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Serum insulin-like growth factor-1 concentrations in healthy cats before and after weight gain and weight loss
Eric Zini1,2,3, Elena Salesov1, Anke Willing1
1Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Background:
Measurement of serum concentrations of insulin-like growth factor (IGF)-1 is used to diagnose acromegaly in cats.
Hypothesis:
Changes of body weight do not affect serum concentrations of IGF-1 in cats.
Animals:
Ten healthy purpose-bred cats.
Methods:
Prospective study. In lean cats, food availability was stepwise increased during the first week and given ad libitum for a total of 40 weeks to increase their body weight. From week 41 to week 60, food access was limited to reach a weight loss of 1% to 2% each week. Measurement of IGF-1 was performed at week 0, 16, 40, and 60. Insulin-like growth factor-1 was measured by radioimmunoassay. Body weight and IGF-1 were compared among the 4 time points.
Results:
Body weight increased by 44% from week 0 (4.5 ± 0.4 kg) to week 40 (6.5 ± 1.2 kg) (P < .001) and decreased by 25% from week 40 to week 60 (4.9 ± 0.7 kg) (P < .001). Serum IGF-1 concentrations did not differ during the study period (week 0, 16, 40, 60: 500 ± 188, 479 ± 247, 470 ± 184, 435 ± 154 ng/mL, respectively; P = .38). Correlations with body weight were not observed.
Conclusions And Clinical Importance:
Insulin-like growth factor-1 might not be influenced by changes of body weight in healthy cats, possibly suggesting that the latter is unimportant when interpreting IGF-1 results in this species.
