Functional and scintigraphic evaluation of the silent adrenal mass

Seven patients with unilateral and one patient with bilateral and asymmetric (R>L) incidentally discovered adrenal mass abnormalities depicted by computed tomography (CT) were studied by ¹³¹I-6β-iodomethyl-19-norcholesterol (NP-59) scintigraphy. There was marked lateralization of NP-59 uptake to the side of the mass lesion in the seven patients with unilateral masses and prominent asymmetric, (R>L) bilateral uptake in the patient with bilateral masses despite the fact that there were no obvious abnormalities of adrenocortical or adrenomedullary function as determined from peripheral blood and 24-hr urinary hormone measurements. Simultaneous bilateral adrenal vein catheterization (AVC) was employed to measure the levels of hormone effluent from the adrenal cortex and medulla and in all instances the cortisol concentrations were greatest from the side of the mass lesion in those patients with unilateral masses and from the larger of the two adrenals in the patient with bilateral adrenal masses. Thus, there was congruence between the anatomic (CT) and functional (NP-59 scintigraphy and AVC) investigations that depicted asymmetry of the adrenal glands which were not associated with abnormalities of overall adrenal function or hypothalamic-pituitary-adrenal axis integrity.