Failure of Classical β-Blocker Carvedilol to Deactivate Brown Adipose Tissue in a Patient With Pheochromocytoma

A 37-year-old woman with pheochromocytoma underwent presurgical FDG PET/CT. Despite her usual antiadrenergic medication consisting in 25 mg of carvedilol, PET/CT demonstrated intense and widespread FDG uptake in brown adipose tissue (BAT). No BAT FDG uptake was detectable on a repeated examination after specific preparation consisting in 40 mg propranolol and 5 mg diazepam. We therefore recommend this propranolol-diazepam preparation in patients with pheochromocytoma referred for PET/CT. Carvedilol-classically prescribed to alleviate effects of adrenergic overstimulation-seems ineffective on BAT. This observation questions the benefit of carvedilol to reduce β3-adrenoreceptor-mediated effects, not only in BAT, but also in other tissues.