49 THE ABNORMALITY OF GLUCOSE TOLERANCE TEST IN PHEOCHROMOCYTOMA: ONE OF THE SIGNIFICANT FINDINGS OF POSTOPERATIVE HYPOGLYCEMIA

Abstract

INTRODUCTION AND OBJECTIVES: The resection of pheochromocytoma inevitably includes several possible life-threatening complications. Although the blood pressure control was investigated, there have been few studies regarding postoperative hypoglycemia. The aim of this study is to analyze the correlation between preoperative variables and postoperative hypoglycemia. METHODS: This study included 14 patients who underwent surgical removal of pheochromocytoma and intraand postoperative closed glucose monitorings. Preoperative variables included age, tumor size, urinary catecholamine levels, HbA1c, 75g oral glucose tolerance test, homeostasis model assessment of insulin resistance, Urinary excretion of C-peptide immunoreactivity and Insulinogenic index. Glucose tolerance was categorized into normal glucose tolerance (NGT), impaired fasting glycemia (IFG), impaired glucose tolerance (IGT) or diabetes mellitus (DM) according to the WHO criteria. We analyzed the relationship of these preoperative parameters and postoperative hypoglycemia. Hypoglycemia was defined as a serum glucose level of 72 mg/dl. RESULTS: Postoperative hypoglycemia was occurred in eight of 14 patients (57.1%). All of them were glucose intolerance group consisting of one IFG, 4 IGT and 3 DM. All 6 patients with normal glucose tolerance did not develop postoperative hypoglycemia. The mean level of lowest glucose was 68.1 20.0 mg/dl in patients with glucose intolerance group. On the other hand, the mean level of lowest glucose was 101.2 16.6 mg/dl in normal glucose tolerance group. Lowest glucose level was significantly lower in the glucose intolerance group (p 0.019). Univariate analysis revealed glucose intolerance had statistically significant (p 0.0003) association with postoperative hypoglycemia. Urinary norepinephrine level (p 0.0028) and age (p 0.02) also had significant association with postoperative hypoglycemia. CONCLUSIONS: Glucose tolerance test abnormality is one of the significant findings of postoperative hypoglycemia. Pheochromocytoma patients with this sign should be monitored closely. Source of Funding: None