Glucocorticoid-remediable aldosteronism.

Although GRA is said to be one of the least common of the mineralocorticoid-excess states, it is probably underdiagnosed. Moreover, recent advances in our understanding of its pathogenesis has greatly broadened the understanding of this disorder. The development of direct genetic testing for GRA has simplified the diagnostic approach to GRA and will likely increase the detection of many previously undiagnosed cases. Since appropriate treatment can often result in normalization of this refractory form of hypertension, a high index of suspicion should be maintained for this diagnosis when a patient is diagnosed with mineralocorticoid-induced hypertension. It is only through early detection and institution of directed treatment that the morbidity and mortality associated with GRA can be reduced.

Hereditary hypertension caused by chimaeric gene duplications and ectopic expression of aldosterone synthase.

Patients with glucocorticoid-remediable aldosteronism (GRA) from 12 kindreds possess chimaeric gene duplications arising from unequal crossing-over, fusing regulatory sequences of steroid 11 beta-hydroxylase to coding sequences of aldosterone synthase. These chimaeric genes are specific for GRA and explain the biochemistry, physiology and genetics of this form of hypertension. Sites of crossing over range from intron 2 to intron 4. Most mutations have arisen independently from either sister or non-sister chromatid exchange between these genes, which are only 45 kilobases apart. The possibility of a susceptibility allele for GRA of Irish origin is suggested. These findings indicate the utility of a direct genetic test for this disorder.

Cyclosporine A and prednisone-associated osteoporosis in heart transplant recipients.

Immunosuppressive therapy with cyclosporine A or prednisone produces bone loss in some animal models. Although we have clinically observed osteoporotic fractures in our heart recipients, the effects of cyclosporine and prednisone on bone density in transplant populations has not been fully elucidated. This study was undertaken to examine indexes of mineral metabolism and bone mineral density (BMD) in heart transplant recipients referred for evaluation of possible bone disease. Twenty of 93 patients who underwent heart transplantation at our institution were evaluated for osteoporosis. Sixteen of these patients (eight men; eight women) were included in this cross-sectional study (two patients were excluded because of hyperparathyroidism, and two patients were excluded because severe fractures prevented BMD from being measured). The mean age of the heart transplant recipients was 52.4 +/- 2.2 years, and the study was conducted a mean of 33.4 +/- 4.6 (men) and 19.0 +/- 7.0 (women) months after heart transplantation. Forty-four percent of these heart transplant recipients were seen clinically with fractures. Biochemical tests of skeletal homeostasis and BMD measurements with dual energy x-ray absorptiometry were performed. In male and female patients, the indexes of mineral metabolism showed (mean +/- sem) osteocalcin levels of 9.60 +/- 2.3 micrograms/L and 9.46 +/- 1.9 micrograms/L (normal: men, 6.39 +/- 0.69 micrograms/L; women, 5.87 +/- 0.71 micrograms/L) and intact parathyroid hormone levels of 48.8 +/- 10.3 ng/L and 63.4 +/- 10.7 ng/L (normal: men, 26.8 +/- 3.3 ng/L; women, 30.7 +/- 2.1 ng/L), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucocorticoid-remediable aldosteronism in a large kindred: clinical spectrum and diagnosis using a characteristic biochemical phenotype.

OBJECTIVE: To define the clinical spectrum of glucocorticoid-remediable aldosteronism (GRA) in a large kindred. DESIGN: Screening all at-risk relatives of a proband for GRA using a specific biochemical phenotype and collecting of medical histories of kindred members from five generations. SETTING: Outpatient General Clinical Research Centers and patients' homes. MEASUREMENTS: Screening was done while patients were on a self-selected diet and included blood pressure determinations; serum potassium and plasma renin activity and aldosterone measurements; and 24-hour urinary tetrahydroaldosterone, 18-oxotetrahydrocortisol, and 18-hydroxycortisol measurements. RESULTS: Diagnosis of GRA was established on the basis of a previously described specific biochemical abnormality, overproduction of the cortisol C-18 oxidation products (18-oxotetrahydrocortisol and 18-hydroxycortisol) in urine and their ratio relative to tetrahydroaldosterone. Glucocorticoid-remediable aldosteronism was diagnosed in 11 additional patients spanning three generations; this group included the youngest patient (3 months old) ever diagnosed with GRA. Complete penetrance of the biochemical abnormality is likely, with 11 of 18 at-risk patients displaying the phenotype. All patients with GRA had elevated blood pressure. Affected adult patients had been diagnosed as hypertensive before reaching 21 years of age (n = 7 mean, 16.1 +/- 3.4 years). All affected patients were normokalemic (4.3 +/- 0.3 mmol/L). CONCLUSION: Hypertension is a characteristic feature of GRA. Elevated blood pressure in this kindred developed at an early age and often was severe. Because a normal potassium level does not exclude the diagnosis of GRA, the disorder may be underdiagnosed. The value of a specific cortisol C-18 oxidation phenotype in the diagnosis of GRA has been confirmed.

A chimaeric 11 beta-hydroxylase/aldosterone synthase gene causes glucocorticoid-remediable aldosteronism and human hypertension.

Glucocorticoid-remediable aldosteronism (GRA), an autosomal dominant disorder, is characterized by hypertension with variable hyperaldosteronism and by high levels of the abnormal adrenal steroids 18-oxocortisol and 18-hydroxycortisol, which are all under control of adrenocorticotropic hormone and suppressible by glucocorticoids. These abnormalities could result from ectopic expression of aldosterone synthase, which is normally expressed only in adrenal glomerulosa, in the adrenal fasciculata. Genes encoding aldosterone synthase and steroid 11 beta-hydroxylase (expressed in both adrenal fasciculata and glomerulosa), which are 95% identical and lie on chromosome 8q (refs 7, 10), are therefore candidate genes for GRA. Here we demonstrate complete linkage of GRA in a large kindred to a gene duplication arising from unequal crossing over, fusing the 5' regulatory region of 11 beta-hydroxylase to the coding sequences of aldosterone synthase (maximum lod score 5.23 for complete linkage, odds ratio of 170,000:1). This mutation can account for all the physiological abnormalities of GRA. Our result represents the demonstration of a mutation causing hypertension in otherwise phenotypically normal animals or humans.

Blood pressure and renal blood flow responses to dietary calcium and sodium intake in humans.

This study was designed to determine the interaction between salt and calcium intake on blood pressure (BP) and renal blood flow (RBF) in a predominantly white population. We measured BP and RBF (P-aminohippurate [PAH] clearance) in hypertensive patients after 7 days on a low salt/low calcium diet and again after either a high salt/high calcium diet (HS/HC) or a high salt/low calcium (HS/LC) diet for another 7 days. Compared to low salt BP, both high salt diets increased BP, but the increase with high salt/low calcium was significantly greater than with high salt/high calcium (+14.6 +/- 3.9/+8.2 +/- 1.7 mm Hg v +7.5 +/- 1.9/+2.5 +/- 1.4 mm Hg; systolic/diastolic, both P less than or equal to .05). PAH clearance increased 26 +/- 13 mL/min/1.73 m2 on the HS/HC diet but only 10 +/- 17 mL/min/1.73 m2 on HS/LC (P = .05 between groups). These data suggest that a low calcium diet may contribute to the phenomenon of salt sensitivity in a white population. The low calcium intake appears to affect both the systemic and renal vasculature.