Resolution of diabetes mellitus but not acromegaly in a cat with a pituitary macroadenoma treated with hypofractionated radiation

Abstract

The use of insulin-like growth factor 1 assays in the diagnosis and subsequent monitoring after radiotherapy of an acromegalic cat with a secretory pituitary adenoma and secondary insulin-resistant diabetes mellitus is described. Diabetes resolved, and exogenous insulin was no longer required for the maintenance of normoglycaemia 10 months after completion of a course of hypofractionated radiotherapy. However, insulin-like growth factor 1 remained elevated, and the cat's size and appetite continued to increase. It is suggested that radiotherapy may decrease growth hormone concentration to a level such that diabetogenic effects are no longer evident but not to a level required to decrease insulin-like growth factor 1 secretion.

Disorders of Growth Hormone

“…In the studies described in the past, types and techniques of radiation (Cobalt-60, betatron, linear accelerator), treatment planning (manual or computerized), as well treatment protocols (number of fractions, total radiation dose) varied considerably (Goossens et al, 1998;Peterson et al, 1990;Kaser-Hotz et al, 2002;Brearley et al, 2006;Littler et al, 2006;Mayer et al, 2006;Dunning et al, 2009;Sellon et al, 2009). In the studies described in the past, types and techniques of radiation (Cobalt-60, betatron, linear accelerator), treatment planning (manual or computerized), as well treatment protocols (number of fractions, total radiation dose) varied considerably (Goossens et al, 1998;Peterson et al, 1990;Kaser-Hotz et al, 2002;Brearley et al, 2006;Littler et al, 2006;Mayer et al, 2006;Dunning et al, 2009;Sellon et al, 2009).…”

“…In the studies described in the past, types and techniques of radiation (Cobalt-60, betatron, linear accelerator), treatment planning (manual or computerized), as well treatment protocols (number of fractions, total radiation dose) varied considerably (Goossens et al, 1998;Peterson et al, 1990;Kaser-Hotz et al, 2002;Brearley et al, 2006;Littler et al, 2006;Mayer et al, 2006;Dunning et al, 2009;Sellon et al, 2009). Interestingly, in several of those cases, diabetes was well controlled or even in remission (Littler et al, 2006;Dunning et al, 2009). Many of the treatments are not state-of-theart anymore and, therefore, results have to be interpreted with care.…”

Serum N‐Terminal Type III Procollagen Propeptide: An Indicator of Growth Hormone Excess and Response to Treatment in Feline Hypersomatotropism

“…As in previous studies, no significant difference was found in IGF‐1 concentration pre‐ and post‐RT in HSDM cats . Ideally, more cats would have been recruited into this group.…”

“…This finding could indicate a lack of consistent efficacy of RT as a treatment for HS. Indeed, even in cases which see diabetes resolved after RT, ongoing soft tissue changes have been observed . Alternatively, RT may be associated with a late onset of treatment effect .…”

Concurrent somatotroph and plurihormonal pituitary adenomas in a cat

“…28,36 Bilateral adrenalectomy, radiotherapy and hypophysectomy have also been described as therapies for pituitary hyperadrenocorticism in cats. [29][30][31][37][38][39][40][41][42][43][44] Radiotherapy may temporarily resolve or control DM; however, acromegalic and hyperadrenocorticoid changes frequently persist. [40][41][42][43]45,46 Conclusions This is the second report of a cat with two discrete, morphologically distinct pituitary lesions consisting of a somatotrophic adenoma and a separate plurihormonal adenoma with positive immunohistochemistry for ACTH, FSH and MSH.…”