Catecholamine-induced metabolic dysfunction and its reversal postsurgery in pheochromocytoma-paraganglioma patients: Insights from the "PheoMet" study.

BACKGROUND

Catecholamine excess in pheochromocytoma-paraganglioma is believed to result in numerous metabolic implications leading to insulin resistance and glucose intolerance.

METHODS

PheoMet was a prospective cohort study including 40 pheochromocytoma-paraganglioma patients and 20 age- and sex-matched controls with nonfunctioning adrenal tumors. Patients with comorbidities affecting metabolism were excluded. Metabolic evaluation comprised oral glucose tolerance testing with serial glucose, insulin, and C-peptide measurements preoperatively, early postoperatively (1-2 weeks), and at 6-month follow-up. Derived indices included homeostatic model assessment of insulin resistance, homeostatic model assessment of β-cell function, insulinogenic index, and disposition index. Lipid profile and hemoglobin A1c were also analyzed.

RESULTS

Patients and controls were age and sex matched. Study group patients had higher baseline systolic blood pressure and 24-hour urinary metanephrines and normetanephrines compared with controls; these normalized following surgery. Pheochromocytoma-paraganglioma patients demonstrated higher fasting glucose and postprandial glucose at 30, 60, 90, and 120 minutes, which declined significantly postsurgery across all postoperative time points (P = .001). Hemoglobin A1c showed a progressive decline from 6.18% ± 0.89 preoperatively to 5.51% ± 0.51 at 6 months. Insulin and C-peptide levels did not change significantly over time. Homeostatic model assessment of insulin resistance did not show any significant changes, whereas disposition index increased significantly from 0.57 (0.20-1.44) to 0.86 (0.56-1.67) (P = .02). Lipid profile did not exhibit any statistically significant longitudinal changes.

CONCLUSION

Pheochromocytoma-paraganglioma causes reversible catecholamine-mediated metabolic dysfunction. Curative surgery results in early and sustained improvement in glucose homeostasis. These results suggest the utility of comprehensive metabolic assessment in pheochromocytoma-paraganglioma patients.