Feline Hypersomatotropism, an Important Cause for the Failure of Insulin Therapy

Abstract

Introduction: Hypersomathotropism is an important feline endocrinopathy, induced by a pituitary growth hormone secreting adenoma. Up until present, most of the diagnosed acromegalic cats were diagnosed previously with insulin dependent diabetes mellitus. Aims: Hypersomathotropism needs imperative exclusion when dealing with poor blood glucose control and insulin resistance. The present paper describes hypersomathotropism diagnosis protocol in two insulin resistant diabetic felines. Material and methods: Two diabetic domestic short hair cats presenting marked insulin resistance and poor blood glucose control were evaluated. Diagnosis protocol included anamnesis, physical evaluation and general and specific biochemistry analysis. Diagnosis confirmation was obtained on contrast enhanced intracranial MRI and morphopathological examination. Results: Both cases displayed marked insulin resistance with 1.5 IU/kg/administration in the male cat (10.5 IU/administration) and 2.4 I.U./kg/administration in the female cat (12 I.U./administration). On physical examination have been observed a slight inferior prognathia on the female cat, clubbed paws on the male cat, broad facial features and obesity (female: 5kg; male: 7 kg). Repeated blood glucose curves confirmed persistent hyperglycaemia >450 mg/dl (61-124 mg/dl) with different doses of insulin. Specific biochemistry revealed an increased concentration of insulin like growth factor-1 determination >1000 ng/ml (208 - 443 ng/ml), above the cut-off for hypersomathotropism diagnosis. Contrast enhanced MRI revealed an enlarged pituitary gland confirming hypersomathotropism. Haematoxylin eosin examination of the pituitary tissue revealed acidophilic cells consistent with growth hormone producing cells. Conclusions: Systemic manifestations are masked by diabetes mellitus clinical signs leading to a high error degree in diagnostic establishment and administration of highly dangerous doses of insulin. With accurate diagnosis, case management and specific treatment can be applied accordingly and in the favor of patient quality of life.