Diagnosis and management of primary aldosteronism

Primary aldosteronism and its various clinical scenarios

BACKGROUND

Primary aldosteronism is the most frequent endocrine cause of secondary hypertension. Aldosterone excess damages the cardiovascular system.

OBJECTIVES

We compared biochemical; morphological, and cardiovascular risk differences among hypokalemic and normokalemic primary aldosteronism. We evaluated either both presentations correspond to two different entities or a unique disease in different evolutive stage.

MATERIAL AND METHODS

This is a retrospective study including 157 patients with primary aldosteronism divided into two groups: typical presentation (serum potassium < 3.5 mmol/l, n = 87) and atypical presentation (serum potassium > 3.5 mmol/l, n = 70).

RESULTS

The typical presentation group showed higher family background of ischemic heart disease (P = 0.028), plasmatic aldosterone levels (P = 0.001), and cardiovascular added risk (P = 0.013). Although kalemia was corrected in the hypokalemic group after specific treatment, typical presentation maintained lower levels. Predictors of typical presentation were the highest tertile of aldosterone level, baseline DBP, and a longer evolution of hypertension. Aldosterone serum levels increased along time in primary aldosteronism and it can be considered as the most discriminative factor for the type of presentation.

CONCLUSION

Primary aldosteronism presentation along with normokalemia or hypokalemia could be the same disease at different evolution stages. Adequate detection of normokalemic primary aldosteronism deserves an early and intentional diagnostic attitude.

T45G and G276T Adiponectin Gene Polymorphisms in Primary Aldosteronism and Healthy Controls in an East Slovak Population

Metabolic complications are frequent in primary aldosteronism (PA) and adiponectin gene polymorphisms seem to confer a genetic risk for metabolic alterations. Aim of the study was to evaluate the prevalence of metabolic symptoms in patients with PA compared to controls and the prevalence of two single nucleotide polymorphisms (SNPs), T45G and G276T, in the adiponectin gene and their relationship to metabolic syndrome (MS). The study involved 47 patients with PA and 90 controls selected from general population. Body mass index (BMI), and selected biochemical parametres were examined, and the mentioned SNPs were genotyped in all subjects. PA patients had a significantly higher BMI (p0.0001), blood glucose level (p0.01), and triglycerides (p0.0005) compared to controls. There were no significant differences in the prevalence of the studied genotypes of adiponectin gene polymorphisms. The 276GT genotype was linked with lower levels of triglycerides (p≤0.05), while 276GG was related to higher levels of triglycerides (p=0.01). A similar but non-significant tendency was observed in relation to cholesterol levels. We can conclude that PA patients with the 276GT genotype have lower triglycerides levels, but there are not significant differences in the distribution of genotypes and alleles among PA patients and controls in an East Slovak population.

Hypertension caused by primary hyperaldosteronism: increased heart damage and cardiovascular risk

INTRODUCTION AND OBJECTIVES

Primary hyperaldosteronism is the most common cause of secondary hypertension. Elevated aldosterone levels cause heart damage and increase cardiovascular morbidity and mortality. Early diagnosis could change the course of this entity. The objective of this report was to study the clinical characteristics, cardiac damage and cardiovascular risk associated with primary hyperaldosteronism.

METHODS

We studied 157 patients with this diagnosis. We analyzed the reason for etiological investigation, and the routinely performed tests, including echocardiography. We used a cohort of 720 essential hypertensive patients followed in our unit for comparison.

RESULTS

Compared with essential hypertensive patients, those with hyperaldosteronism were younger (56.9 [11.7] years vs 60 [14.4] years; P<.001), had higher blood pressure prior to the etiological diagnosis (136 [20.6] mmHg vs 156 [23.2] mmHg), more frequently had a family history of early cardiovascular disease (25.5% vs 2.2%; P<.001), and had a higher prevalence of concentric left ventricular hypertrophy (69% vs 25.7%) and higher cardiovascular risk. Specific treatment resulted in optimal control of systolic and diastolic blood pressures (from 150.7 [23.0] mmHg and 86.15 [14.07] mmHg to 12.69 [15.3] mmHg and 76.34 [9.7] mmHg, respectively). We suspected the presence of hyperaldosteronism because of resistant hypertension (33.1%), hypokalemia (38.2%), and hypertensive crises (12.7%). Only 4.6% of these patients had been referred from primary care with a suspected diagnosis of hyperaldosteronism.

CONCLUSIONS

Hyperaldosteronism should be suspected in cases of resistant hypertension, hypokalemia and hypertensive crises. The diagnosis of hyperaldosteronism allows better blood pressure control. The most prevalent target organ damage is left ventricular hypertrophy.

Mineralocorticoid hypertension

Hypertension affects about 10 - 25% of the population and is an important risk factor for cardiovascular and renal disease. The renin-angiotensin system is frequently implicated in the pathophysiology of hypertension, be it primary or secondary. The prevalence of primary aldosteronism increases with the severity of hypertension, from 2% in patients with grade 1 hypertension to 20% among resistant hypertensives. Mineralcorticoid hypertension includes a spectrum of disorders ranging from renin-producing pathologies (renin-secreting tumors, malignant hypertension, coarctation of aorta), aldosterone-producing pathologies (primary aldosteronism - Conns syndrome, familial hyperaldosteronism 1, 2, and 3), non-aldosterone mineralocorticoid producing pathologies (apparent mineralocorticoid excess syndrome, Liddle syndrome, deoxycorticosterone-secreting tumors, ectopic adrenocorticotropic hormones (ACTH) syndrome, congenitalvadrenal hyperplasia), and drugs with mineraocorticoid activity (locorice, carbenoxole therapy) to glucocorticoid receptor resistance syndromes. Clinical presentation includes hypertension with varying severity, hypokalemia, and alkalosis. Ratio of plasma aldosterone concentraion to plasma renin activity remains the best screening tool. Bilateral adrenal venous sampling is the best diagnostic test coupled with a CT scan. Treatment is either surgical (adrenelectomy) for unilateral adrenal disease versus medical therapy for idiopathic, ambiguous, or bilateral disease. Medical therapy focuses on blood pressure control and correction of hypokalemia using a combination of anti-hypertensives (calcium channel blockers, angiotensin converting enzyme inhibitors, or angiotensin receptor blockers) and potassium-raising therapies (mineralcorticoid receptor antagonist or potassium sparing diuretics). Direct aldosterone synthetase antagonists represent a promising future therapy.

Mineralocorticoids stimulate the activity and expression of renal H+,K+-ATPases

In the renal collecting duct, mineralocorticoids drive Na(+) reabsorption, K(+) secretion, and H(+) secretion through coordinated actions on apical and basolateral transporters. Whether mineralocorticoids act through H(+),K(+)-ATPases to maintain K(+) and acid-base homeostasis is unknown. Here, treatment of mice with the mineralocorticoid desoxycorticosterone pivalate (DOCP) resulted in weight gain, a decrease in blood [K(+)] and [Cl(-)], and an increase in blood [Na(+)] and [HCO(3)(-)]. DOCP treatment increased the rate of H(+),K(+)-ATPase-mediated H(+) secretion in intercalated cells of the inner cortical collecting duct. mRNA expression of the catalytic subunit HKα(1) did not significantly change, whereas HKα(2) mRNA expression dramatically increased in the outer and inner medulla of DOCP-treated mice. A high-K(+) diet abrogated this increase in renal HKα(2) expression, showing that DOCP-mediated stimulation of HKα(2) expression depends on dietary K(+) intake. DOCP treatment of mice lacking HKα(1) (HKα(1)(-/-)) resulted in greater urinary Na(+) retention than observed in either wild-type mice or mice lacking both HKα(1) and HKα(2) (HKα(1,2)(-/-)). DOCP-treated HKα(1,2)(-/-) mice exhibited a lower blood [HCO(3)(-)] and less Na(+) and K(+) retention than either wild-type or HKα(1)(-/-) mice. Taken together, these results indicate that H(+),K(+)-ATPases-especially the HKα(2)-containing H(+),K(+)-ATPases-play an important role in the effects of mineralocorticoids on K(+), acid-base, and Na(+) balance.

The heme oxygenase system attenuates pancreatic lesions and improves insulin sensitivity and glucose metabolism in deoxycorticosterone acetate hypertension

Recent clinical reports indicate that impaired glucose tolerance is a common phenomenon in primary aldosteronism. Aldosterone stimulates NF-κB and activating protein-1 (AP-1) to cause oxidative injury. Elevated oxidative stress impairs insulin signaling. We recently showed that the heme oxygenase (HO) system lowers blood pressure (BP) in deoxycorticosterone-acetate (DOCA)+salt hypertension, a model of primary aldosteronism. However, the effect of the HO system on insulin sensitivity in this model remains largely unclear. Here we report the effects of the HO-inducer hemin and the HO-blocker [chromium mesoporphyrin (CrMP)] on insulin sensitivity/glucose metabolism. Our experimental design included the following 10 groups: (A) controls [(i) surgery-free or normal Sprague-Dawley (SD), (ii) uninephrectomized (UnX)-sham, (iii) UnX+salt (0.9%NaCl+0.2%KCl) and (iv) UnX+DOCA]; (B) DOCA+salt; (C) hemin+DOCA+salt; (D) hemin+CrMP+DOCA+salt; (E) CrMP+DOCA+salt; (F) vehicle-treated rats and (G) normal SD+hemin. Hemin therapy lowered BP and increased plasma insulin and the insulin-sensitizing protein adiponectin with slight but significant reduction of glycemia, while CrMP abolished the hemin effects. Furthermore, hemin improved intraperitoneal glucose and insulin tolerance, suggesting that although DOCA+salt-hypertensive rats were normoglycemic, insulin signaling may be impaired. In contrast, the HO-inhibitor CrMP aggravated insulin resistance and exacerbated glucose and insulin tolerance. Interestingly, the enhanced insulin sensitization in hemin-treated animals was accompanied by reduced urinary/gastrocnemius muscle 8-iso-prostaglandin F2α (8-isoprostane), inflammatory/oxidative transcription factors like NF-κB, AP-1, JNK, and heme content, whereas HO-1, HO-activity, cGMP, and plasma/gastrocnemius muscle antioxidants including bilirubin, ferritin, SOD, catalase, and the total antioxidant capacity were increased. Similarly, hemin enhanced pancreatic HO, cGMP, and cAMP but suppressed 8-isoprostane and attenuated pancreatic histopathological lesions including fibrosis, interstitial edema, acinar cell necrosis, vacuolization, and mononuclear cell infiltration, with corresponding improvement of insulin production. Our results suggest that impaired insulin signaling may be a forerunner to hyperglycemia in aldosteronism. By preserving pancreatic morphology, potentiating insulin signaling, and lowering BP, the HO system may prevent metabolic and cardiovascular complications in aldosteronism.