TORONTO — Children who become obese following surgical removal of craniopharyngiomas exhibit more severe metabolic derangements than do equally obese children who did not have the tumors, Dr. Jill Hamilton reported at the annual joint meeting of the Canadian Diabetes Association and the Canadian Society for Endocrinology and Metabolism.
Craniopharyngioma, a tumor of the hypothalamic-pituitary region, accounts for 9% of all intracranial tumors in children. Although the tumor itself is benign, hypothalamic trauma resulting from its surgical removal often leads to a variety of neurologic and metabolic problems, including morbid obesity in 35%–58% of patients. The mechanism is not clear, but vagally-mediated increased insulin secretion appears to play a role, said Dr. Hamilton, of the University of Toronto and the Hospital for Sick Children, Toronto.
Fifteen children (mean age 15.2 years) with a history of craniopharyngioma treatment and body mass index (BMI) greater than the 95th percentile for age and sex (mean 35.0) were compared with 15 control children matched for both age (mean 14.8 years) and BMI (32.9) who did not have a history of the tumor. There were 8 girls and 7 boys in the craniopharyngioma group, who had a mean Tanner Stage of 3, versus 10 girls and 5 boys in the control group, mean Tanner Stage 4. The two groups did not differ with regard to family history of type 2 diabetes, parental obesity, or in utero exposure to diabetes.
Oral glucose tolerance tests demonstrated significantly higher 2-hour glucose values among the craniopharyngioma children, compared with the controls (137 mg/dL vs. 115.3 mg/dL [7.6 mmol/L vs. 6.4 mmol/L]), as well as significantly elevated insulin levels at 30 minutes and 2 hours. Forty percent of the craniopharyngioma group met diagnostic criteria for either impaired glucose tolerance or type 2 diabetes (previously undiagnosed), compared with none of the controls, Dr. Hamilton reported.
Two-thirds of the craniopharyngioma group versus just 20% of the controls—a significant difference—met pediatric-adapted criteria for the metabolic syndrome, mostly via elevated triglycerides, reduced HDL cholesterol, and impaired glucose tolerance.
Whole-body insulin sensitivity did not differ between the two groups, but the craniopharyngioma patients demonstrated significantly elevated first- and second-phase insulin secretion, she said.