RECENT FINDINGS: KCNJ5, ATP1A1, ATP2B3, CACNA1D, CTNNB1, and CACNA1H mutations are causal of primary aldosteronism. ARMC5 may cause bilateral lesions resulting in primary aldosteronism.LGR5, DACH1, and neuron-specific proteins are highly expressed in the zona glomerulosa and regulate aldosterone production.
SUMMARY: Most mutations causing primary aldosteronism are in genes encoding cation channels or pumps, leading to increased calcium influx. Genotype-phenotype analyses identified two broad subtypes of aldosterone-producing adenomas (APAs), zona fasciculata-like and zona glomerulosa-like, and the likelihood of under-diagnosed zona glomerulosa-like APAs because of small size. Zona fasciculata-like APAs are only associated with KCNJ5 mutations, whereas zona glomerulosa-like APAs are associated with mutations in ATPase pumps, CACNA1D, and CTNNB1. The frequency of APAs, and the multiplicity of causal mutations, suggests a pre-existing drive for these mutations. We speculate that these mutations are selected for protecting against tonic inhibition of aldosterone in human zona glomerulosa, which express genes inhibiting aldosterone production.
DESIGN: In the present SCOT-PA survey, we have investigated the diversity of approaches utilized for each diagnostic step in different expert centers through a survey using Google questionnaires. A total of 33 centers from 3 continents participated.
RESULTS: We demonstrated a prominent diversity in the conditions of blood sampling, assay methods for aldosterone and renin, and the methods and diagnostic cutoff for screening and confirmatory tests. The most standard measures were modification of antihypertensive medication and sitting posture for blood sampling, measurement of plasma aldosterone concentration (PAC) and active renin concentration by chemiluminescence enzyme immunoassay, a combination of aldosterone-to-renin ratio with PAC as an index for screening, and saline infusion test in a seated position for confirmatory testing. The cutoff values for screening and confirmatory testing showed significant variation among centers.
CONCLUSIONS: Diversity of the diagnostic steps may lead to an inconsistent diagnosis of PA among centers and limit comparison of evidence for PA between different centers. We expect the impact of this diversity to be most prominent in patients with mild PA. The survey raises 2 issues: the need for standardization of the diagnostic process and revisiting the concept of mild PA. Further standardization of the diagnostic process/criteria will improve the quality of evidence and management of patients with PA.
METHODS: This was an open-label, prospective, case-controlled study, conducted over 12 months. Fifty-two consecutive patients referred for secondary hypertension were screened. Eighteen patients with confirmed PA (diagnosis based on the Endocrine Society clinical guideline) and seventeen matched controls with essential hypertension were recruited. BTM (CTX and P1NP), BMD, intact parathyroid hormone (iPTH), and bone profile were assessed at baseline and three months following treatment among the PA patients. Calcium intake was assessed using a validated questionnaire. Primary outcomes were the changes of bone markers and BMD following treatment of PA, and their relation to other parameters.
RESULTS: PA patients had significantly lower serum calcium and higher iPTH despite comparable vitamin D levels with control group. Both BTM were significantly higher among the PA group. BMD of lumbar spine, neck of femur and distal radius did not differ between groups. Three months following treatment, there were significant: 1) reduction in BTM; 2) improvement in the lumbar spine BMD; 3) reduction in iPTH level; and 4) increment of serum 25-OH vitamin D level.
CONCLUSIONS: Our findings support that bone loss and potential fracture risk among PA patients are likely a result of aldosterone-mediated secondary hyperparathyroidism. Patients with early PA may already exhibit increased bone turnover despite no significant changes in BMD.
EVIDENCE ACQUISITION: We conducted a meta-analysis to evaluate the relationship between primary aldosteronism (PA) with bone biochemical markers and to assess bone mineral density in patients with primary aldosteronism.
EVIDENCE SYNTHESIS: A total of 939 subjects were examined (37.5% with PA). Patients with PA had significantly higher serum parathyroid hormone, lower serum calcium, higher urine calcium excretion and higher serum alkaline phosphatase compared to patients without PA, with no significant difference in serum vitamin D between both groups. Bone mineral density of lumbar spine, femoral neck and total neck of femur were similar between two groups. With PA treatment, there was a significant increment in serum calcium and reduction in serum parathyroid hormone.
CONCLUSIONS: PA is associated with hypercalciuria with subsequent secondary hyperparathyroidism. This potentially affects bone health. We recommend this to be part of complication screening among patients with PA.
Case presentation: We report 2 cases of hypertension with secondary hyperaldosteronism associated with accessory renal arteries. Both patients presented with hypokalemia and further investigations revealed hyperaldosteronism with unsuppressed renin levels. Imaging studies showed the presence of accessory renal artery.
Conclusion: Accessory renal arteries are a potential cause renovascular hypertension which can be detected via CT angiography or magnetic resonance angiography. Hormonal evaluation should be undertaken to determine whether its presence contributes to hypertension in the patient as targeted treatment such as aldosterone antagonist can be initiated. Surgical intervention or renal denervation may be considered in resistant cases.