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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adrenocortical causes of hypertension are established by examining the mineralocorticoid hormones produced in the zona glomerulosa and zona fasciculata. In the zona glomerulosa, aldosterone excess leads to hypertension, hypokalemia, and suppressed plasma renin activity, with increased concentrations of urinary aldosterone (either as the 18-glucuronide or free aldosterone) as an index of its production. Identifying a tumor by computed tomography scan verifies the diagnosis of a correctable lesion. If no tumor is found, several maneuvers are used to identify primary adrenal hyperplasia, a disorder with autonomous aldosterone production, for which reduction of adrenal mass is curative. The zona fasciculata has two major pathways: the 17-deoxy pathway, where deoxycorticosterone (DOC) and corticosterone are the significant steroids, and the 17-hydroxy pathway, which leads to cortisol production. Tumors of the 17-deoxy pathway, DOC-producing adenomas, have increased concentrations of DOC and its precursor steroids, normal concentrations of cortisol, and suppression of aldosterone production secondary to suppression of the renin system. Two enzymatic defects in the zona fasciculata, 11 beta- and 17 alpha-hydroxylase deficiency, can be first readily identified by the virilization in the former, hypogonadal features in the latter. Steroid patterns are diagnostic. DOC is produced in excess in both deficiencies and is the cause of the hypertension. Deficient or impaired 11 beta-hydroxy steroid dehydrogenase in the apparent mineralocorticoid excess syndrome or after licorice ingestion retards the conversion of cortisol to inactive cortisone in the kidney, leading to mineralocorticoid hypertension; this leads to suppression of the renin system and subsequently of aldosterone.
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PMID:Steroid characteristics of mineralocorticoid adrenocortical hypertension. 191

We review various theories of the pathogenetic mechanisms of steroid-induced and essential hypertension. We investigated the possibility that a pathogenetic mechanism leading to glucocorticoid (GC)-induced hypertension or to mineralocorticoid (MC)-induced hypertension, or both, may be of critical importance in primary hypertension. We studied plasma levels of corticosterone (BK) and aldosterone (Aldo), and their concentrations in arterial and renal tissues of spontaneously hypertensive rats (SHR), a model of primary hypertension, and in the antecedent strain WKY rats as a normotensive control. Plasma levels of BK and Aldo were found to be normal and identical in SHRs and WKYs. Tissue (intracellular) levels of BK were more than double in SHRs than in WKYs. Subsequently we examined the activity of 11 beta-hydroxy steroid dehydrogenase (11-HSD) in both aortic and renal tissues of SHRs and WKYs. 11-HSD converts BK to the corresponding 11-keto compound, 11-dehydro-corticosterone (cpd.AK), which is inactive, in view of its inability to bind to the MC receptors (and also to the GC receptors). BK, the main glucocorticoid in the rat, as well as cortisol, have high affinity for the MC-receptor (MR). Normally BK or cortisol are present in 10(2)-10(3) times greater concentrations than Aldo in tissues possessing MR. The enzyme 11-HSD deactivates BK (or cortisol), thus protecting MC-receptors in the MC target tissues from being activated by GC. When we examined arterial and renal tissue activities of 11-HSD in SHRs, the activity of 11-HSD was only one-third that found in the WKY rats. This explained higher levels of BK in the tissues of SHR, and suggested that decreased activity of 11-HSD is a pathogenetic factor for hypertension in SHRs. Thus, in a model of primary hypertension such as SHR, decreased activity of 11-HSD in the target tissues of MC appears to lead to glucocorticoid-induced mineralocorticoid hypertension.
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PMID:[Mechanism of primary hypertension]. 1090 53

A 60-year-old woman presented with a history of palpitations, headaches and severe hypertension, which was resistant to hypotensive agents. She had a 2-year history of obesity and a moon face. Her plasma adrenocorticotropic hormone level was below the limits of detection and did not respond to corticotropin-releasing hormone. Urinary-free cortisol was elevated and the circadian rhythm of serum cortisol level had completely disappeared. Imaging analysis demonstrated a unilaterally functioning mass in the left adrenal gland. Serum cortisol level in the left adrenal vein was elevated. The resected adrenal mass measured 4 x 3.5 x 2.5 cm, and ranged from yellow to tan in color. The adrenal cortex adjacent to the nodule did not demonstrate cortical atrophy. The mass was well circumscribed but not encapsulated, and consisted of multiple cortical nodules. These nodules were composed predominantly of clear cortical cells, and partly of compact cortical cells. Immunoreactivity of steroidogenic enzymes including cholesterol side-chain-cleavage P450, 3beta-hydroxysteroid dehydrogenase, 21-hydroxylase cytochrome P450, 11beta-hydroxylase cytochrome P450 and 17alpha-hydroxylase cytochrome P450 was marked in cortical nodules, but minimal in non-nodular cortex. Ultrastructural examination of nodular cortical cells also demonstrated well-developed mitochondria and smooth endoplasmic reticulum, consistent with elevated steroidogenesis in these cells.
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PMID:Adrenocorticotropin-independent unilateral adrenocortical hyperplasia with Cushing's syndrome: Immunohistochemical studies of steroidogenic enzymes, ultrastructural examination and a review of the literature. 1116 51

Adrenarche is the puberty of the adrenal gland. The descriptive term "pubarche" indicates the appearance of pubic hair, which may be accompanied by axillary hair. This process is considered premature if it occurs before age 8 yr in girls and 9 yr in boys. The chief hormonal products of adrenarche are DHEA and DHEAS. The well-documented evolution of adrenarche in primates and men is incompatible with either a neutral or harmful role for DHEA and implies most likely a positive role for some aspects of young adult pubertal maturation and developmental maturation. Premature adrenarche has no adverse effects on the onset and progression of gonadarche and/or final height. Mechanisms for initiation of adrenal androgen secretion at adrenarche are still not well understood. Maturational increases in 17-hydroxylase and 17,20-lyase are seen together with a lower activity of 3beta-hydroxysteroid dehydrogenase (3beta-HSD). There is good evidence that the zona reticularis is the source of adrenal androgens. Adrenarche and gonadarche are regulated differently. Although premature adrenarche has been thought to be a benign, normal variant of puberty, our findings indicate that, for certain girls, premature adrenarche represents an early clinical feature of syndrome X (obesity, hypertension, dyslipidemia, insulin resistance). Perhaps the early identification of these patients will permit early therapy, such as lifestyle changes, including dietary and activity level intervention. As insulin resistance is an underlying feature of premature adrenarche, it seems rational to assess the efficacy and safety of using insulin-sensitizing agents to treat these individuals. In the absence of controlled longitudinal studies, the cross-sectional data available from our studies suggest that premature pubarche driven by premature adrenarche and hyperinsulinemia may precede the development of ovarian hyperandrogenism, and this sequence may have an early origin with low birth weight serving as a marker. Premature adrenarche may thus be a forerunner of syndrome X in some girls.
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PMID:Premature adrenarche. 1171 59

Primary aldosteronism is classified as aldosterone-producing adenoma (APA), idiopathic hyperaldosteronism (IHA), unilateral adrenal hyperplasia (UAH), primary adrenal hyperplasia (PAH), adrenal cancer, and glucocorticoid-remediable aldosteronism. We describe here 4 cases of primary aldosteronism due to unilateral hyperaldosteronemia, demonstrating unique histopathologic findings, such as unilateral multiple adrenocortical micronodules in the affected adrenals. Thirty-three patients with primary aldosteronism were consecutively admitted; 27 of them were treated by unilateral adrenalectomy. Four of them also had unilateral adrenal hypersecretion of aldosterone by selective adrenal venous sampling and adrenocortical multiple micronodules without an adenoma. These patients had hyporeninemic hyperaldosteronism with normokalemic hypertension. In these patients, furosemide plus upright test failed to increase plasma renin activity (PRA); the ratio of plasma aldosterone concentration (PAC) to PRA at 90 minutes after captopril administration was similar to that in patients with IHA and APA. Aldosterone concentrations were increased in each unilateral adrenal vein, and poorly encapsulated multiple adrenocortical micronodules from 2 to 3 mm in diameter were microscopically detected in the resected adrenal glands. Immunohistochemical analysis of steroidogenic enzymes, including cholesterol side chain cleavage, 3beta-hydroxysteroid dehydrogenase, 21-hydroxylase, 17alpha-hydroxylase, and 11beta-hydroxylase, indicated that the cortical cells within these micronodules were active in aldosterone production, while the non-nodular zona glomerulosa cells were inactive. We conclude that the clinical and pathologic characteristics of our 4 cases with unilateral multiple adrenocortical micronodules (UMN) are distinct from those of APA, IHA, UAH, and PAH. Furthermore, unilateral hyperaldosteronemia induced by UMN may be frequently misdiagnosed, because standard imaging tests, which cannot always detect tiny abnormalities of adrenals, showed "normal adrenal glands" in these patients. Thus, primary aldosteronism due to UMN should be carefully examined for differential diagnosis of each form of hyperaldosteronemia.
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PMID:Unique cases of unilateral hyperaldosteronemia due to multiple adrenocortical micronodules, which can only be detected by selective adrenal venous sampling. 1188 72

Congenital adrenal hyperplasia (CAH) refers to a family of inherited disorders of adrenal steroidogenesis in which each disorder is characterized by a specific enzyme deficiency that impairs cortisol production by the adrenal cortex. The enzymes most commonly affected are 21-hydroxylase (21-OH), 11beta-hydroxylase, 3beta-hydroxysteroid dehydrogenase, and less often, 17alpha-hydroxylase/17,20-lyase and cholesterol desmolase. Many of the corresponding genes for the described enzymes have been isolated and characterized, and specific mutations causing CAH have been identified. In classical CAH (simple virilizing and salt wasting forms), androgen excess causes external genital ambiguity in newborn females and progressive postnatal virilization in both sexes. In nonclassical CAH, 21-OHD is partial and occurs with milder symptoms. A deficiency of 11beta-Hydroxylase deficiency results in ambiguous genitalia in the newborn genetic female and androgen excess and hypertension in both males and females. In 3beta-hydroxysteroid deficiency adrenal and gonadal androgen production is deficient resulting in incomplete genital development in genetic males and limited androgen affect in females. Two less frequent causes of CAH 17alpha-Hydroxylase/17,20-lyase and cholesterol desmolase result in external female genitalia in both sexes. Hormonal diagnosis is described for each disorder.
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PMID:Inborn errors of adrenal steroidogenesis. 1465 79

The three zones of the human adrenal cortex are functionally distinct with the glomerulosa producing aldosterone, the fasciculata producing cortisol, and the reticularis producing DHEA/DHEAS. This functional zonation is largely due to the zone-specific expression of steroidogenic enzymes. Recent evidence suggests a role for the NGFI-B family of orphan nuclear receptors (particularly NURR1 and NGFI-B) in the zone-specific expression of two key steroidogenic enzymes, aldosterone synthase (CYP11B2) and 3beta-hydroxysteroid dehydrogenase (HSD3B2). Herein we discuss the evidence that suggests a role for NURR1 (NR4A2) in the expression of CYP11B2 in the glomerulosa as well as in the dysregulation of CYP11B2 gene expression as is seen in aldosterone-producing adenoma (APA), a major cause of endocrine hypertension. NURR1 appears to be important for CYP11B2 transcription and is found at higher levels in glomerulosa and in APA. Its expression in adrenal cells is also readily increased by angiotensin II treatment. HSD3B2 is a steroid-metabolizing enzyme that is essential for adrenal production of mineralocorticoids and glucocorticoids. Thus, HSD3B2 is expressed at high levels in the glomerulosa and fasciculata where these steroids are produced but at low levels in the adrenal reticularis, which produces mainly DHEA. We recently demonstrated that NGFI-B (nur77 or NR4A1) plays an important role in the regulation of HSD3B2 transcription and may play an important role in the functional zonation of the adrenal gland. Immunohistochemistry confirmed that, within adult and fetal adrenal gland, NGFI-B expression paralleled expression of HSD3B2. Transient transfections demonstrated that NGFI-B family members enhanced HSD3B2 reporter activity but had no effect on a 17alpha-hydroxylase (CYP17) promoter construct. Taken together these results suggest that the NGFI-B family of transcription factors plays a role in establishing the functional zonation of the human adrenal by regulating CYP11B2 and HSD3B2 gene transcription.
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PMID:A role for the NGFI-B family in adrenal zonation and adrenocortical disease. 1566 93

A 46-year-old male with long-term treatment-resistant hypertension and past history of cerebral hemorrhage was found to have suppressed plasma renin activity (PRA) and normal plasma aldosterone concentration (PAC) with aldosterone/renin ratio of 25.3. Furosemide plus upright test did not stimulate PRA, but computed tomography scan of the abdomen revealed no abnormal lesions in either adrenal gland. Selective adrenal venous sampling (SAVS) showed that PAC in the left and the right adrenal vein were 1000 ng/dl and 230 ng/dl, respectively, which increased to 1500 ng/dl and 620 ng/dl, respectively, after ACTH stimulation. Diagnosis of primary aldosteronism due to hypersecretion of aldosterone from the left adrenal gland was made, and laparoscopic left adrenalectomy was performed. Pathological examination of the 'apparently normal' adrenal tissue resected revealed the presence of poorly encapsulated multiple adrenocortical micronodules which showed positive immunoreactivity for 3beta-hydroxysteroid dehydrogenase by immunohistochemical study, but negative immunoreactivity in the hyperplastic zona glomerulosa consistent with paradoxical hyperplasia associated with primary aldosteronism. Postoperatively, PRA was normalized and his high blood pressure was well controlled with lower doses of antihypertensive drugs than those used before surgery. The clinicopathological features of our case are consistent with the diagnosis of unilateral multiple adrenocortical micronodules (UMN), a new subset of primary aldosteronism, in which SAVS proved to be a useful diagnostic tool for its localization.
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PMID:A case with primary aldosteronism due to unilateral multiple adrenocortical micronodules. 1612 11

The case of a patient with primary aldosteronism due to unilateral adrenal hyperplasia (UAH) is reported. A 43-year-old man with an 8-year history of hypertension presented at our institution with hypokalemia, increased plasma aldosterone concentration (PAC), and suppressed plasma renin activity (PRA). An abdominal CT scan showed almost normal adrenal glands with slight enlargement in the left gland. 131I-Norcholesterol adrenal scintigraphy under dexamethasone suppression showed bilaterally decreased uptake. To rule out idiopathic hyperaldosteronism, an adrenal vein sampling before and after ACTH stimulation was performed and a left-sided lateralization of PAC was observed. A left adrenalectomy was performed, and the patient had a good clinical and biochemical response. Micronodular hyperplasia was discovered in the adrenal gland histologically, and in the immunohistochemical analysis, positive staining for 3beta-hydroxysteroid dehydrogenase in micronodular lesions confirmed the diagnosis of UAH. Although UAH is a rare subset of primary aldosteronism, it is surgically correctable as a unilateral autonomous aldosterone-producing lesion. Careful investigations, including bilateral adrenal vein sampling, should be performed for the diagnosis.
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PMID:A case of primary aldosteronism due to unilateral adrenal hyperplasia. 1613 69

The short-chain oxidoreductase (SCOR) family of enzymes includes over 6,000 members identified in sequenced genomes. Of these enzymes, approximately 300 have been characterized functionally, and the three-dimensional crystal structures of approximately 40 have been reported. Since some SCOR enzymes are steroid dehydrogenases involved in hypertension, diabetes, breast cancer, and polycystic kidney disease, it is important to characterize the other members of the family for which the biological functions are currently unknown and to determine their three-dimensional structure and mechanism of action. Although the SCOR family appears to have only a single fully conserved residue, it was possible, using bioinformatics methods, to determine characteristic fingerprints composed of 30-40 residues that are conserved at the 70% or greater level in SCOR subgroups. These fingerprints permit reliable prediction of several important structure-function features including cofactor preference, catalytic residues, and substrate specificity. Human type 1 3beta-hydroxysteroid dehydrogenase isomerase (3beta-HSDI) has 30% sequence identity with a human UDP galactose 4-epimerase (UDPGE), a SCOR family enzyme for which an X-ray structure has been reported. Both UDPGE and 3-HSDI appear to trace their origins back to bacterial 3alpha,20beta-HSD. Combining three-dimensional structural information and sequence data on the 3alpha,20beta-HSD, UDPGE, and 3beta-HSDI subfamilies with mutational analysis, we were able to identify the residues critical to the dehydrogenase function of 3-HSDI. We also identified the residues most probably responsible for the isomerase activity of 3beta-HSDI. We test our predictions by specific mutations based on sequence analysis and our structure-based model.
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PMID:Determining structure and function of steroid dehydrogenase enzymes by sequence analysis, homology modeling, and rational mutational analysis. 1646 63


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