Influence of medroxyprogesterone acetate (Provera) on plasma growth hormone levels and on carbohydrate metabolism. I. Studies in the ovariohysterectomized bitch.

Six elderly ovariohysterectomized dogs were given medroxyprogesterone acetate (MPA 10 mg/kg body weight) at 3 week intervals in a total of 5 injections. Mean growth hormone (GH) levels increased significantly after the third injection, continued to increase slightly after the fourth and fifth injections and remained significantly elevated over control levels as late as 16 weeks after the last MPA administration (P less than 0.05). The mean glucose concentrations during iv glucose tolerance tests (IVGTT) were significantly elevated at 30, 45 and 60 min after a glucose load when performed after the third MPA injection. Following the second MPA injection, mean insulin levels were significantly elevated at rest, 30 and 45 min after glucose load. After the fourth and fifth MPA injections, mean insulin levels during IVGTT were significantly elevated at 30 min only. These findings denote that (1) after a lag phase of several weeks MPA induces moderate GH increase in ovariohysterectomized dogs; (2) MPA administration causes moderate disturbance of glucose homoeostasis.