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Biomedical subjects

Robert G Dluhy

Publications and source records attributed to Robert G Dluhy.

13 recordsLinked to original sources

Glucocorticoid-remediable aldosteronism.

Glucocorticoid-remediable aldosteronism (GRA) is a monogenic form of human hypertension that predisposes to cerebral hemorrhage. As a result of a chimeric gene duplication, aldosterone is ectopically synthesized in the cortisol-secreting zona fasciculata of the adrenal gland under the control of adrenocorticotropin (ACTH). Hypertension frequently has its onset during childhood and is usually refractory to standard anti-hypertensives such as ACE inhibitors and beta-blockers. Hypokalemia can develop in those treated with a potassium-wasting diuretic, but random potassium levels are usually normal. Diagnosis has been facilitated by the availability of a genetic test. Suppression of ACTH release with exogenous dexamethasone is a useful diagnostic and therapeutic strategy. Treatment with the mineralocorticoid receptor antagonists spironolactone and epleronone is also efficacious. The diagnosis of GRA facilitates directed therapies and screening of at-risk individuals and kindreds.

Glucocorticoids↗

Diagnosis of primary aldosteronism: from screening to subtype differentiation.

Numerous studies conducted in recent years have reported an increase in the prevalence of primary aldosteronism (PA). This increase has arisen because of changes in our screening methods used to detect PA, notably the widespread use of the ratio of plasma aldosterone concentration to plasma renin activity. A positive screening result, however, is not diagnostic and requires a confirmatory test. Strategies for screening and confirmation of PA and the techniques to identify the two main subtypes of PA--aldosterone-producing adenoma (APA) and bilateral adrenal hyperplasia (BAH)--are particularly important because hypertension in APA can be cured by adrenalectomy, whereas individuals affected with BAH can receive targeted medical treatment with mineralocorticoid receptor antagonists.

Adenoma↗

Screening for genetic causes of hypertension.

Monogenic or single-gene forms of human hypertension result from mutations involving regulatory elements of the renin-angiotensin-aldosterone system (RAAS) or occur in syndromes associated with hereditary pheochromocytoma. RAAS gain-of-function mutations result in sodium retention, suppression of plasma renin activity, and often, but not invariably, hypokalemia. Hereditary RAAS syndromes result from intrinsic renal abnormalities (apparent mineralocorticoid excess and Liddle's syndromes) or from mineralocorticoid excess states (congenital adrenal hyperplasia and glucocorticoid-remediable aldosteronism). In the hereditary pheochromocytoma syndromes many asymptomatic individuals are identified because they are at-risk individuals in kindreds with a pheochromocytoma-predisposing syndrome. On the other hand, up to 25% of subjects with presumed "sporadic" pheochromocytoma have germline mutations in one of four pheochromocytoma susceptibility genes (the RET proto-oncogene, von Hippel-Lindau gene, neurofibromatosis F1 gene, and succinate dehydrogenase subunit D and succinate dehydrogenase subunit B genes). Hereditary pheochromocytomas are typically intra-adrenal and bilateral and patients typically present at younger ages compared with sporadic pheochromocytoma.

Adrenal Gland Neoplasms↗

Peripheral amino acid and fatty acid infusion for the treatment of necrolytic migratory erythema in the glucagonoma syndrome.

Necrolytic migratory erythema (NME), the characteristic rash associated with the glucagonoma syndrome, is a cause of substantial morbidity among patients with this rare malignancy. Treatment options are suboptimal, and often useful for only short or moderate durations. We report the effective, long-term (> 1 year) use of intermittent infusions of amino acids (AA) and fatty acids (FA) administered via peripheral intravenous access for the treatment of NME in the glucagonoma syndrome. Despite resolution of the NME, serum amino acid (initially subnormal) and fatty acid (initially normal) levels remained unchanged. Tumour growth and other symptoms related to the glucagonoma syndrome appear unaffected by such infusions.

Amino Acids↗

Glucocorticoid-remediable aldosteronism.

Glucocorticoid remediable aldosteronism (GRA) appears to be the most common monogenic form of human hypertension. As a result of chimeric gene duplication, aldosterone is ectopically synthesized in the zona fasciculata of the adrenal gland under the control of adrenocorticotropin (ACTH). Affected individuals are typically hypertensive, often with onset in youth, and demonstrate refractoriness to standard antihypertensives such as angiotensin-converting enzyme inhibitors and beta-blockers. GRA subjects are normokalemic but often develop hypokalemia when treated with a potassium-wasting diuretic. Analysis of affected kindreds has demonstrated a high prevalence of early cerebral hemorrhage, largely as a result of aneurysms. Identification of affected individuals should allow direct neurovascular screening and targeted antihypertensive therapy.

Aldosterone↗