Cryohypophysectomy for acromegaly: Factors associated with altered endocrine function and carbohydrate metabolism

Abstract

After Cryohypophysectomy, fasting levels of growth hormone (GH) fell to less than 10 ng/ml in 38 (76 per cent) of 50 patients with acromegaly. Effects, including lowered serum insulin levels and improved glucose tolerance, were rapid and long-lasting. Optimal endocrine-metabolic results, defined as lowering of the GH level to 10 ng/ml or less and normal glucose tolerance (attained in 60 per cent of patients), were most often achieved when preoperative glucose tolerance was normal or mildly abnormal. Factors that favored optimal lowering of GH were preoperative GH level below 50 ng/ml and moderately, rather than greatly, enlarged sellae turcica. Factors that favored normal carbohydrate balance after treatment were postoperative fasting GH level of 10 ng/ml or less and preoperative symptom duration of 10 years or less. A family history of diabetes was not an important over-all factor in glucose intolerance. Although postoperative reduction in 24-hour urinary excretion of 17-hydroxycorticosteroids was associated with adequate GH reduction, adrenal reserve and thyroid function remained normal in most patients. In contrast to the prognostic significance of high GH levels, adrenal and thyroid function could not be related to eventual GH response or to carbohydrate metabolism.