Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 24-1992. A 52-year-old man with hypertension, hypokalemia, and an adrenal mass

PCR-SSCP analysis of the angiotensin II type 1 receptor gene in patients with aldosterone-producing adenomas

1. In patients with primary aldosteronism due to angiotensin-responsive and angiotensin-unresponsive aldosterone-producing adenomas, no differences in the coding region of the angiotensin II type 1 (AT1) receptor gene were observed compared to normal subjects in peripheral blood leucocyte DNA. 2. Furthermore, no differences in the AT1 receptor gene were observed in DNA extracted from tumour tissue of either subgroup. 3. Genotypic and allelic frequencies for an RFLP detected in the coding region of the AT1 receptor gene were not significantly different between normal subjects and patients with aldosterone-producing adenomas as a group, nor between normal subjects and patients of either subgroup when compared with each other. 4. In those patients heterozygous in peripheral blood at the RFLP site, tumour DNA showed the same allelic pattern. 5. In patients with aldosterone-producing adenomas either responsive or unresponsive to the renin-angiotensin system, no differences were detected using SSCP analysis in the coding region of the AT1 receptor gene in peripheral blood or tumour tissue.

Angiotensin-responsive aldosterone-producing adenomas: postoperative disappearance of aldosterone response to angiotensin

1. Nineteen out of 47 patients (40%) with confirmed unilateral aldosterone-producing adenoma (APA) were responsive to low-dose angiotensin II infusion (AII-R), as defined by an increase in plasma aldosterone concentration of > 50% over basal at 2 ng/kg per min for 60 min. 2. Seven to ten days after unilateral adrenalectomy, aldosterone was no longer responsive to angiotensin infusion in AII-R APA (100%, n = 17). Therefore, angiotensin responsiveness resides within the adenoma in AII-R APA. 3. The upright posture test for the differentiation of adenoma from hyperplasia was unreliable for the AII-R APA (26%), but generally reliable in the angiotensin-unresponsive subtype, (AII-U APA, 96%). 4. The reported predominance of females in APA was seen in AII-U APA (68%), but was reversed in AII-R APA (37%).

Primary aldosteronism: hypertension with a genetic basis

Exciting developments in knowledge of primary aldosteronism include description of new subtypes and elucidation of the genetic basis of one variety. Furthermore, relatively simple biochemical screening (aldosterone/renin ratio) has disclosed that primary aldosteronism is more common than previously thought, by diagnosing patients at an earlier, normokalaemic stage. The mutant gene discovered in the glucocorticoid-suppressible variety (FHI) codes for an aldosterone biosynythetic enzyme normally controlled by angiotensin II, and now controlled by corticotropin. The zona fasciculata is hyperplastic and makes aldosterone and "hybrid steroids" 18-oxocortisol and 18-hydroxycortisol in excess, in response to ACTH but not to angiotensin II. Adrenal tumours have not yet been described in this condition. Aldosterone-producing adenomas (Conn's syndrome) are also commonly composed of zona fasciculata-like cells, make "hybrid steroids" in excess and are very sensitive to ACTH but not to angiotensin II. We have described a new variety of aldosterone-producing adenoma which is responsive to angiotensin II (AII-responsive APA), consists of at least 20% zona glomerulosa-like cells, and does not make "hybrid steroids" in excess. We have also described a new familial variety of primary aldosteronism that includes tumours and is not glucocorticoid-suppressible (FHII). We propose that primary aldosteronism is a spectrum of genetic diseases expressed as either hyperplasia or neoplasia, and that morphological and genetic diversity explains biochemical and clinical behaviour.