METABOLIC EFFECTS OF PHARMACOLOGICAL ADRENERGIC-BLOCKADE IN PHEOCHROMOCYTOMA

Twelve-hour hormonal and metabolic profiles were performed in a 68-year-old woman with a benign adrenal phaeochromocytoma (a) prior to adrenergic blockade, (b) after the establishment of pharmacological alpha-blockade with phenoxybenzamine, (c) after combined alpha and beta-blockade with phenoxybenzamine and propranolol, and (d) after successful surgery and withdrawal of medication. Pretreatment, (a) vs (d), significant elevations (12-h mean +/- SD) were observed in the concentrations of noradrenaline (44.9 +/- 14.4 vs 2.3 +/- 0.7 nmol/l, P < 0.01), glucose (6.9 +/- 1.9 vs 5.0 +/- 1.0 mmol/l, P < 0.05), glycerol (0.22 +/- 0.02 vs 0.07 +/- 0.01 mmol/l, P < 0.01), non-esterified fatty acids (0.71 +/- 0.28 vs 0.34 +/- 0.08 mmol/l, P < 0.01), and total ketone bodies (0.08 +/- 0.03 vs 0.03 +/- 0.02 mmol/l, P < 0.01). Alpha-blockade, (b) vs (a), was associated with an increase in noradrenaline levels (P < 0.01) but not with any significant alterations in intermediary metabolite concentrations. Following the establishment of combined alpha and beta-blockade, (c) vs (b), plasma noradrenaline returned to its pretreatment level while the concentrations of glycerol, fatty acids and ketone bodies were normalized. A completely physiological 12-h blood glucose profile, however, was observed only post-operatively. No significant differences were observed in mean plasma insulin levels between the four studies. These results indicate impaired regulation of multiple aspects of carbohydrate, lipid and ketone body metabolism in our patient. Alpha-blockade did not ameliorate the abnormalities in any aspect of intermediary metabolism and was associated with an increase in noradrenaline levels. Combined alpha and beta-blockade effectively normalized lipolysis and ketone body metabolism but did not fully correct the abnormality in glucose metabolism.