The relationship of adrenal gland iodomethylnorcholesterol uptake to zona glomerulosa function in primary aldosteronism

Therapeutic outcome of primary aldosteronism: adrenalectomy versus enucleation of aldosterone-producing adenoma

Our followup study of 48 patients with primary aldosteronism concerns the results of 2 different operative methods. After preoperative localization of the unilateral solitary tumor 22 patients underwent unilateral adrenalectomy and 26 underwent enucleation of aldosterone-producing adenoma. Both operative methods improved hypertension, hypokalemia, the low urinary sodium-to-potassium ratio, suppressed plasma renin activity, high plasma aldosterone concentration, high urinary aldosterone excretion and high urinary kallikrein excretion in similar orders of magnitude for 5 years. Levels of plasma cortisol and plasma adrenocorticotropic hormone following respective operations were also identical. Five years postoperatively, ambulation and furosemide administration under low sodium diet stimuli remarkably enhanced plasma renin activity and plasma aldosterone concentration in the aldosterone-producing adenoma enucleation group (p < 0.001), almost similar to that of normal subjects but increment magnitudes were slight (p < 0.05 to < 0.01) in the adrenalectomy group. Preoperatively, angiotensin II infusion failed to increase plasma aldosterone concentration in patients with primary aldosteronism. After respective operations, responses of plasma aldosterone concentration to angiotensin II infusion and of plasma cortisol to adrenocorticotropic hormone administration in the aldosterone-producing adenoma enucleation group were more sensitive than those in the adrenalectomy group. There was no remission of recurrent hyperaldosteronism in either group throughout the study. These results suggest that angiotensin II induces aldosterone release by an activation of tumor uninvolved cortical cells and that the enucleation of aldosterone-producing adenoma is more preferable than unilateral adrenalectomy.

Differential diagnosis of solid adrenal masses using adrenocortical scintigraphy

To evaluate the diagnostic contribution of adrenal scintigraphy with 75-Se-selenomethylcholesterol in adrenal masses, 42 patients have been studied. All of them had a solid adrenal mass discovered on computed tomography (seven bilateral). None of the patients showed any symptoms or clinical signs that might indicate the existence of adrenal dysfunction. Twenty-nine of them had known extra-adrenal primary malignant disease. Forty-nine adrenal tumours were detected with an average size of 3.29 cm (range 1.5-12 cm). Eighteen lesions showed increased uptake of radiocholesterol on the side of the adrenal mass, all of which were either proven to be benign, or behaved in a benign fashion. Twelve lesions showed normal uptake (10 in the benign group and one lung carcinoma metastasis), all but one (2.5 cm) being smaller than 2 cm. Decreased uptake was observed in 20 lesions (15 metastases, two nonfunctional adrenal carcinomas, one myelolipoma and two tuberculous infectious lesions). Adrenocortical scintigraphy provides functional information about adrenal masses and is useful in differentiating between benign and malignant lesions.

[The role of adrenal gland x-ray computed tomography and scintigraphy using radiolabelled norcholesterol in the etiological diagnosis of primary hyperaldosteronism]

The major etiologies of primary aldosteronism are aldosterone-producing adrenal adenoma, requiring a surgical treatment, and bilateral hyperplasia, usually managed with medical therapy. We only report a retrospective study on 22 patients with primary aldosteronism diagnosed by clinical and usual biochemical tests. All the patients were explored by computed tomography scan (CT) and iodomethyl-norcholesterol scintigraphy. The purpose of this study was to compare the capacity of the two methods to differentiate adrenal adenoma and hyperplasia. The CT scan was more sensitive (sensitivity: 88%) compare to scintigraphy (sensitivity: 64%) for the diagnosis of adrenal adenoma. However, the scintigraphy was a useful tool to detect asymmetric macronodular adrenal hyperplasia. Therefore, the catheterisation of adrenal venous would be only necessary for a few cases. We conclude from this study and the literature review that CT scan and iodomethyl-norcholesterol scintigraphy are complementary and both useful to increase diagnostic reliability of primary aldosteronism.

Bilateral adrenal tumours in primary aldosteronism: localization of a unilateral aldosteronoma by dexamethasone suppression scan

In a patient with primary aldosteronism, in which the postural endocrine tests suggested the presence of an aldosteronoma rather than hyperplasia, bilateral adrenal tumours were found by computer tomography. Adrenal scintigraphy using 6-131I-iodomethyl-19-norcholesterol (NP59) during dexamethasone suppression showed early unilateral adrenal visualization on the left side. After removal of the left adrenal gland, which contained a 2 x 2 x 2 cm adenoma, the blood pressure and aldosterone levels returned to normal. A CT-scan, performed 1 year after the pre-operative CT-scan, showed no change in size of the right adrenal tumour, consistent with a non-functioning adenoma. In this patient, the NP59 scan adequately distinguished a non-functioning from an aldosterone-producing adrenal tumour.

False localization of an aldosteronoma by dexamethasone-suppressed adrenal scintigraphy

A patient with primary aldosteronism had bilateral adrenal tumours on computed tomography. Selenocholesterol scintigraphy showed uptake by the larger right adrenal gland and a tumour in the gland was also visualized by venography. In contrast, measurements of aldosterone concentrations in adrenal venous blood lateralized to the left side. At surgery the left adrenal gland contained an aldosteronoma and the right adrenal gland a large non-functioning adenoma. Thus, selenocholesterol scintigraphy incorrectly localized the functioning adrenal tumour.

Scintigraphic localization of adrenal lesions in primary aldosteronism

Dexamethasone suppression adrenal cortical scintiscanning was performed in 87 patients with primary aldosteronism. Fifty patients had adrenal cortical adenomas and 37 had bilateral adrenal hyperplasia. The diagnosis of adrenal cortical adenoma was confirmed by surgery in 49 of 50, and bilateral adrenal hyperplasia was confirmed by adrenal vein aldosterone sampling in 33 and at operation in four. Dexamethasone suppression adrenal scintigraphy correctly identified the lesion(s) in 82 of the 87 patients. There were three false-negative and two false-positive adrenal cortical scintiscanning results. Computed tomography was performed in 33 patients and correctly identified 14 of 23 patients with adrenal cortical adenomas and two of 10 patients with bilateral adrenal hyperplasia and bilateral enlarged adrenals, whereas the remaining eight were considered to have normal findings. These data indicate that, when properly performed, adrenal cortical scintigraphy is an accurate and efficacious modality for the localization of adrenal cortical adenomas and in the differentiation of adrenal cortical adenoma from bilateral adrenal hyperplasia in primary aldosteronism.