Hypophysectomy to treat hypersomatotropism

5 July 2021 – News

Hypophysectomy to treat hypersomatotropism

Hypersomatotropism is a condition increasingly seen in cats and it is caused by a growth hormone (GH) secreting pituitary adenoma. There are several treatment options- medical treatment, radiation therapy, cryotherapy, and surgery. The latter is the treatment of choice for humans.

This investigation considered twenty-five cats with spontaneous hypersomatotropism that underwent transsphenoidal hypophysectomy between 2008 and 2020. It aimed to describe the endocrine profile, survival, and remission rates of hypersomatotropism and diabetes mellitus. Diabetes mellitus was diagnosed in twenty-four cases – in those animals, insulin treatment was initiated before referral, but the glycemic control was insufficient.

The diagnose relied on the clinical signs and plasma insulin-like growth factor-1 concentration. Advanced imaging was also performed in all cases to assess the pituitary dimensions and height and to plan the surgical procedure.

Growth hormone concentrations were measured in preoperative plasma samples and in samples taken 1, 3, and 5 hours postoperatively. Plasma IGF-1 concentrations were measured at diagnosis and repeated perioperatively; marked decreases were noted postoperatively and remission of hypersomatotropism was demonstrated in 23/24 cats. Surgery and recovery were uncomplicated in all animals, but one cat died within 4 weeks after surgery, due to hypoglycemia. Two other cats, in which remission of hypersomatotropism was demonstrated, died in 6-7 weeks after surgery (case unknown – they were found dead without pre-existing signs).

When cats survived the critical postoperative period of 2 to 3 months, prognosis was excellent. Despite the intensiveness of both surgery and perioperative stabilization of hypophysectomy, it can provide and excellent prognosis with a high rate of complete remission for cats with hypersomatotropism and secondary insulin resistant diabetes mellitus, when the investigations and procedures are performed by an experienced team. Hypoglycemia seems to be directly associated with surgical success thus a thorough monitoring of the patient’s demeanour and blood glucose levels in the postoperative period is essential.

van Bokhorst, KL, Galac, S, Kooistra, HS, et al. Evaluation of hypophysectomy for treatment of hypersomatotropism in 25 cats. J Vet Intern Med. 2021; 35: 834– 842. https://doi.org/10.1111/jvim.16047