Aldosterone and parathyroid hormone: a complex and clinically relevant relationship

Hyperparathyroidism in patients with overt and mild primary aldosteronism

INTRODUCTION

Increased prevalence of hyperparathyroidism (HP) has been observed in primary aldosteronism (PA) patients. However, HP prevalence in milder forms of PA has not to date been evaluated.

OBJECTIVES

The objectives of this study were to assess the prevalence of primary and secondary HP in overt and milder misdiagnosed cases of PA and to investigate the effect of treatment on parathormone (PTH) secretion.

PATIENTS AND METHODS

Seventy PA patients with normal renal function were included prospectively. Specifically, patients with biochemically overt PA (increased basal aldosterone/renin ratio (ARR) and a positive diagnostic suppression test (DCVT)) and patients with mild PA (normal basal ARR and a positive DCVT) were analyzed. Mean blood pressure and mineral metabolism were evaluated at diagnosis and after treatment.

RESULTS

Primary and secondary HP were found in 4.3% (3/70) and 51.4% (36/70) of patients, respectively, and biochemically overt and mild PA in 47.1% (33/70) and 52.9% (37/70) of patients, respectively. Sixty-three PA patients were followed up after treatment without receiving calcium or vitamin D. There was a decrease of mean blood pressure (p < 0.001), PTH (p < 0.001), and 24-h urinary calcium (p < 0.001), and an increase of serum potassium (p < 0.001) and calcium (p = 0.018) levels in secondary HP patients. There was no significant difference between biochemically overt and mild PA patients as concerned serum PTH, calcium, and 25-hydroxyvitamin-D levels either before or after treatment. Aldosterone levels before treatment were positively correlated with serum PTH levels.

CONCLUSIONS

HP prevalence was high in both overt and mild PA patients, whereas the effect of treatment on serum and urinary calcium and PTH levels was similar in both groups.

The effect of vitamin D treatment on clinical and biochemical outcomes of primary aldosteronism

INTRODUCTION

Primary aldosteronism (PA) contributed to the cardiovascular disease and metabolic alterations independent of the blood pressure level. Evidence exists that aldosterone excess also affects calcium and mineral homeostasis. PA subjects have been shown to have greater prevalence of vitamin D deficiency. However, the impact of vitamin D treatment in this population has never been assessed.

OBJECTIVE

This study aimed to evaluate the effect of vitamin D treatment on clinical and biochemical outcomes of PA patients.

METHODS

Two hundred forty hypertensive subjects were screened, 31 had positive ARR, and 17 patients with newly confirmed PA following positive confirmatory test that has not been subjected for definitive treatment were enrolled. Clinical parameter (blood pressure) and biochemical parameters (renal profile, plasma aldosterone concentration, plasma renin activity, serum calcium, vitamin D, intact parathyroid hormone, 24-hour urinary calcium) were measured at baseline and 3 months of treatment with Bio-D3 capsule. Primary outcomes were the changes in the blood pressure and biochemical parameters.

RESULTS

About 70% of our PA subjects have low vitamin D levels at baseline. Three months following treatment, there were significant: (a) improvement in 25(OH)D levels; (b) reduction in systolic blood pressure and plasma aldosterone concentration; and (c) improvement in the eGFR. The vitamin D deficient subgroup has the greatest magnitude of the systolic blood pressure reduction following treatment.

CONCLUSIONS

This study demonstrated significant proportion of PA patients has vitamin D insufficiency. Vitamin D treatment improves these interrelated parameters possibly suggesting interplay between vitamin D, aldosterone, renal function and the blood pressure.

The Interplay Between the Renin-Angiotensin-Aldosterone System and Parathyroid Hormone

The renin-angiotensin-aldosterone system (RAAS) is the regulatory system by which renin induces aldosterone production. Angiotensin II (Ang II) is the main effector substance of the RAAS. The RAAS regulates blood pressure and electrolyte balance by controlling blood volume and peripheral resistance. Excessive activation of the RAAS is an important factor in the onset of cardiovascular disease and the deterioration of this disease. The most common RAAS abnormality is primary aldosteronism (PA). Parathyroid hormone (PTH) is a peptide secreted by the main cells of the parathyroid gland, which promotes elevated blood calcium (Ca²⁺) levels and decreased blood phosphorus (Pi) levels. Excessive secretion of PTH can cause primary hyperparathyroidism (PHPT). Parathyroidism is highly prevalent in postmenopausal women and is often associated with secondary osteoporosis. PA and PHPT are common endocrine system diseases. However, studies have shown a link between the RAAS and PTH, indicating a positive relationship between them. In this review, we explore the complex bidirectional relationship between the RAAS and PTH. We also point out possible future treatment options for related diseases based on this relationship.

Parathyroid hormone, aldosterone-to-renin ratio and fibroblast growth factor-23 as determinants of nocturnal blood pressure in primary hyperparathyroidism: the eplerenone in primary hyperparathyroidism trial

OBJECTIVES

The high prevalence of arterial hypertension in primary hyperparathyroidism (pHPT) is largely unexplained. Apart from parathyroid hormone (PTH), the mineral hormones fibroblast growth factor (FGF)-23 and aldosterone-to-renin ratio (ARR) are upregulated in pHPT. We aimed to determine whether nocturnal blood pressure (BP) is related with PTH, FGF-23 or ARR in a relatively large sample of pHPT patients.

METHODS

Cross-sectional data of the single-center "Eplerenone in Primary Hyperparathyroidism" trial were used. All patients with a biochemical diagnosis of pHPT who had both available 24-h ambulatory BP monitoring and valid laboratory data were included.

RESULTS

Full data were available in 136 patients (mean age 67 ± 10 years, 78% women). Median PTH was 99 (interquartile range: 82-124) pg/ml and mean calcium was 2.63 ± 0.15 mmol/l. ARR, but not PTH or FGF-23, was significantly and directly related with nocturnal SBP (Pearson's r = 0.241, P < 0.01) and DBP (r = 0.328, P < 0.01). In multivariate regression analyses, with adjustment for age, sex, PTH, FGF-23, traditional cardiovascular risk factors, antihypertensive medication and parameters of calcium metabolism ARR remained significantly and directly related with nocturnal BP (SBP: adjusted β-coefficient = 0.289, P < 0.01; DBP: β = 0.399, P < 0.01). The relationship between ARR and nocturnal SBP was exclusively present in patients with PTH levels above the median of 99 pg/ml.

CONCLUSION

ARR, but not FGF-23 or PTH, was independently and directly related with nocturnal BP parameters in patients with pHPT, and this relationship was dependent on pHPT disease severity. Inappropriately, elevated aldosterone may partially explain the high prevalence of arterial hypertension in pHPT.

Parathyroid Gland Function in Primary Aldosteronism

Primary aldosteronism (PA) is the most frequent cause of secondary arterial hypertension. Beyond its effects on intravascular volume and blood pressure, PA causes metabolic alterations and a higher cardiovascular morbidity, which is reduced by PA-directed therapy. Experimental studies demonstrated that mineralocorticoid excess may also influence mineral homeostasis. A role in cardiovascular disease has also been attributed to parathyroid hormone (PTH). Increasing evidence supports a bidirectional interaction between aldosterone and PTH.Primary hyperparathyroidism is associated with arterial hypertension and an increased cardiovascular morbidity and mortality, which might be associated to higher aldosterone values; parathyreoidectomy results in lowered aldosterone and blood pressure levels. PA leads to secondary hyperparathyroidism, which is reversible by PA-directed therapy. A lower bone mineral density and a higher fracture rate were also shown to be reversible by PA-directed therapy. There is a suspicion of a bidirectional interaction between aldosterone and PTH, which might lead to a higher cardiovascular risk. There are more and more reports about coincident PA and primary hyperparathyroidism. From a pathophysiologic point of view this constellation is best characterized as tertiary hyperparathyroidism. Future aspects should further clarify the extent of these endocrine interactions and analyze the influence of this interplay on cardiovascular morbidity and mortality and bone health.

Association of low vitamin D levels with metabolic syndrome in hemodialysis patients

Low vitamin D levels have been linked to metabolic syndrome in the general population. In the present study, the relationship between inadequate serum concentrations of vitamin D and metabolic syndrome in patients with end-stage renal disease undergoing hemodialysis was explored. In a cross-sectional setting, 145 patients undergoing maintenance hemodialysis were enrolled. Metabolic syndrome was defined using the International Diabetes Federation criteria. Serum concentration of 25(OH) vitamin D was determined by a commercially available enzyme immunosorbent assay method. The prevalence of metabolic syndrome was 53.1%. The prevalence rate of severe vitamin D deficiency (<5 ng/mL) was 3.4%, mild vitamin D deficiency (5-15 ng/mL) 31.0%, vitamin D insufficiency (16-30 ng/mL) 36.6%, and vitamin D sufficiency (>30 ng/mL) 29.0%. With the increasing number of metabolic abnormalities, vitamin D levels significantly decreased (P for trend = 0.028). Among the components of metabolic syndrome, vitamin D deficiency was significantly associated with central obesity (odds ratio [OR], 95% confident interval [CI] = 2.80, 1.11-7.04, P = 0.028). A positive, but nonsignificant association between vitamin D deficiency and raised fasting plasma glucose was noted (OR, 95% CI = 2.40, 0.94-6.11, P = 0.067). Both vitamin D deficiency and insufficiency were significantly associated with an increased likelihood of having metabolic syndrome (P < 0.05). In a final model controlling for age, sex, and parathyroid hormone levels, vitamin D deficiency increased the odds of having metabolic syndrome by more than threefold (OR, 95% CI = 3.26, 1.30-8.20, P = 0.012). Low levels of vitamin D are frequent among hemodialysis patients and are associated with the metabolic syndrome.

Aldosterone, parathyroid hormone, and the use of renin-angiotensin-aldosterone system inhibitors: the multi-ethnic study of atherosclerosis

CONTEXT

Aldosterone and PTH are implicated in the pathogenesis of cardiovascular and skeletal diseases. An expanding body of evidence supports a bidirectional and positive physiologic relationship between aldosterone and PTH. Large population-based studies confirming this relationship, and whether it may be targeted as a potential method to mitigate the clinical consequences associated with excess aldosterone and PTH, are needed.

OBJECTIVE

We hypothesized that higher aldosterone levels would associate with higher PTH, and that the use of renin-angiotensin-aldosterone system (RAAS) inhibitors would predict lower PTH in a large, multi-ethnic, community-based cohort.

DESIGN, SETTING, PARTICIPANTS

We conducted cross-sectional analyses of participants in the Multi-Ethnic Study of Atherosclerosis without apparent primary hyperparathyroidism or chronic kidney disease (n = 5668). We evaluated associations of RAAS inhibitor use with PTH concentration among 1888 treated hypertensive participants. We also tested associations of serum aldosterone concentration with PTH concentration among 1547 participants with these measurements.

OUTCOME

Serum PTH concentration.

RESULTS

Higher aldosterone associated with higher PTH (β = 0.19 pg/ml per 1 ng/dl of aldosterone, P < .0001), and this finding was most pronounced among those with a primary hyperaldosteronism-like phenotype. There was a stepwise increment in PTH when comparing untreated normotensives, hypertensives using RAAS inhibitors, untreated hypertensives, and treated hypertensives using non-RAAS inhibitors (40.8, 45.0, 46.2, 47.1 pg/ml, respectively). The use of any RAAS inhibitor independently associated with lower PTH (β = -2.327 pg/ml per use of RAAS inhibitor, P = .006), when compared with the use of any non-RAAS inhibitor medication.

CONCLUSIONS

Higher serum aldosterone concentration is associated with higher serum PTH concentration, and the use of RAAS inhibitors is associated with lower PTH concentration. These results extend prior evidence from observational and intervention studies suggesting a potentially important and modifiable relationship between the RAAS and PTH in humans.

A high aldosterone to renin ratio is associated with high serum parathyroid hormone concentrations in the general population

CONTEXT

Activation of the renin-angiotensin-aldosterone system (RAAS) is associated with high serum PTH concentrations and vice versa.

OBJECTIVE

The aim of this study was to analyze the associations of the plasma aldosterone concentration (PAC), the plasma renin concentration (PRC), or the aldosterone to renin ratio (ARR) with serum PTH concentrations in a sample from the general population of northeast Germany.

DESIGN

We selected 3105 subjects (25-88 y) from the first 5-year follow-up examination of the Study of Health in Pomerania. The associations of PAC, PRC, or ARR with serum PTH concentrations were examined with multivariable linear regression analyses. We further calculated adjusted mean serum PTH concentrations according to PAC, PRC, and ARR categories (≥90th and < 90th sex specific percentiles and sex specific quartiles). The models were adjusted for age, sex, estimated glomerular filtration rate, serum 25-hydroxy vitamin D concentration, waist circumference, body mass index, hypertension, diabetes mellitus, liver disease, and intake of drugs that affect the RAAS or bone metabolism.

RESULTS

We found no associations between PAC or PRC and serum PTH concentrations in fully adjusted linear regression models. However, fully adjusted linear regression and ANOVA models revealed higher serum PTH concentrations in subjects with an ARR 90th percentile or greater than in subjects with a lower ARR.

CONCLUSIONS

Our data show that a high ARR is associated with high serum PTH concentrations in the general population and thus add to the increasing evidence of a relation between the RAAS and PTH.

Aldosterone and parathyroid hormone interactions as mediators of metabolic and cardiovascular disease

Inappropriate aldosterone and parathyroid hormone (PTH) secretion is strongly linked with development and progression of cardiovascular (CV) disease. Accumulating evidence suggests a bidirectional interplay between parathyroid hormone and aldosterone. This interaction may lead to a disproportionally increased risk of CV damage, metabolic and bone diseases. This review focuses on mechanisms underlying the mutual interplay between aldosterone and PTH as well as their potential impact on CV, metabolic and bone health. PTH stimulates aldosterone secretion by increasing the calcium concentration in the cells of the adrenal zona glomerulosa as a result of binding to the PTH/PTH-rP receptor and indirectly by potentiating angiotensin 2 induced effects. This may explain why after parathyroidectomy lower aldosterone levels are seen in parallel with improved cardiovascular outcomes. Aldosterone mediated effects are inappropriately pronounced in conditions such as chronic heart failure, excess dietary salt intake (relative aldosterone excess) and primary aldosteronism. PTH is increased as a result of (1) the MR (mineralocorticoid receptor) mediated calciuretic and magnesiuretic effects with a trend of hypocalcemia and hypomagnesemia; the resulting secondary hyperparathyroidism causes myocardial fibrosis and disturbed bone metabolism; and (2) direct effects of aldosterone on parathyroid cells via binding to the MR. This adverse sequence is interrupted by mineralocorticoid receptor blockade and adrenalectomy. Hyperaldosteronism due to klotho deficiency results in vascular calcification, which can be mitigated by spironolactone treatment. In view of the documented reciprocal interaction between aldosterone and PTH as well as the potentially ensuing target organ damage, studies are needed to evaluate diagnostic and therapeutic strategies to address this increasingly recognized pathophysiological phenomenon.

Human interventions to characterize novel relationships between the renin-angiotensin-aldosterone system and parathyroid hormone

Observational studies in primary hyperaldosteronism suggest a positive relationship between aldosterone and parathyroid hormone (PTH); however, interventions to better characterize the physiological relationship between the renin-angiotensin-aldosterone system (RAAS) and PTH are needed. We evaluated the effect of individual RAAS components on PTH using 4 interventions in humans without primary hyperaldosteronism. PTH was measured before and after study (1) low-dose angiotensin II (Ang II) infusion (1 ng/kg per minute) and captopril administration (25 mg×1); study (2) high-dose Ang II infusion (3 ng/kg per minute); study (3) blinded crossover randomization to aldosterone infusion (0.7 µg/kg per hour) and vehicle; and study (4) blinded randomization to spironolactone (50 mg/daily) or placebo for 6 weeks. Infusion of Ang II at 1 ng/kg per minute acutely increased aldosterone (+148%) and PTH (+10.3%), whereas Ang II at 3 ng/kg per minute induced larger incremental changes in aldosterone (+241%) and PTH (+36%; P<0.01). Captopril acutely decreased aldosterone (-12%) and PTH (-9.7%; P<0.01). In contrast, aldosterone infusion robustly raised serum aldosterone (+892%) without modifying PTH. However, spironolactone therapy during 6 weeks modestly lowered PTH when compared with placebo (P<0.05). In vitro studies revealed the presence of Ang II type I and mineralocorticoid receptor mRNA and protein expression in normal and adenomatous human parathyroid tissues. We observed novel pleiotropic relationships between RAAS components and the regulation of PTH in individuals without primary hyperaldosteronism: the acute modulation of PTH by the RAAS seems to be mediated by Ang II, whereas the long-term influence of the RAAS on PTH may involve aldosterone. Future studies to evaluate the impact of RAAS inhibitors in treating PTH-mediated disorders are warranted.

Cardiovascular diseases in older patients with osteoporotic hip fracture: prevalence, disturbances in mineral and bone metabolism, and bidirectional links

BACKGROUND

Considerable controversy exists regarding the contribution of mineral/bone metabolism abnormalities to the association between cardiovascular diseases (CVDs) and osteoporotic fractures.

AIMS AND METHODS

To determine the relationships between mineral/bone metabolism biomarkers and CVD in 746 older patients with hip fracture, clinical data were recorded and serum concentrations of parathyroid hormone (PTH), 25-hydroxyvitamin D, calcium, phosphate, magnesium, troponin I, parameters of bone turnover, and renal, liver, and thyroid functions were measured.

RESULTS

CVDs were diagnosed in 472 (63.3%) patients. Vitamin D deficiency was similarly prevalent in patients with (78.0%) and without (82.1%) CVD. The CVD group had significantly higher mean PTH concentrations (7.6 vs 6.0 pmol/L, P < 0.001), a higher prevalence of secondary hyperparathyroidism (SPTH) (PTH > 6.8 pmol/L, 43.0% vs 23.3%, P < 0.001), and excess bone resorption (urinary deoxypyridinoline corrected by creatinine [DPD/Cr] > 7.5 nmol/μmol, 87.9% vs 74.8%, P < 0.001). In multivariate regression analysis, SHPT (odds ratio [OR] 2.6, P = 0.007) and high DPD/Cr (OR 2.8, P = 0.016) were independent indictors of CVD. Compared to those with both PTH and DPD/Cr in the normal range, multivariate-adjusted ORs for the presence of CVD were 17.3 (P = 0.004) in subjects with SHPT and 9.7 (P < 0.001) in patients with high DPD/Cr. CVD was an independent predicator of SHPT (OR 2.8, P = 0.007) and excess DPD/Cr (OR 2.5, P = 0.031). CVD was predictive of postoperative myocardial injury, while SHPT was also an independent predictor of prolonged hospital stay and in-hospital death.

CONCLUSION

SHPT and excess bone resorption are independent pathophysiological mediators underlying the bidirectional associations between CVD and hip fracture, and therefore are important diagnostic and therapeutic targets.

Demonstration of Blood Pressure-Independent Noninfarct Myocardial Fibrosis in Primary Aldosteronism

Background—

Primary aldosteronism (PA) is common and associates with excess cardiovascular morbidity independent of blood pressure. Exposure to aldosterone and sodium leads to cardiac fibrosis and hypertrophy in humans and animals possibly mediated by inflammation and oxidative stress. We aimed to clarify the effects of aldosterone excess on myocardial structure and composition in human subjects with PA and essential hypertension using contrast-enhanced cardiac magnetic resonance imaging as well as explore the mechanistic basis for any observed differences.

Methods and Results—

Twenty-seven subjects with recently diagnosed PA and 54 essential hypertension controls were recruited. Subjects underwent gadolinium-enhanced cardiac magnetic resonance; noninfarct related myocardial fibrosis was identified by a diffuse pattern of late gadolinium enhancement. Patients also underwent assessment of pulse wave velocity, measurement of circulating superoxide anion and C-reactive protein, as well as blood pressure and biochemical assessment. Subjects were well matched with no difference in severity or duration of hypertension. There was a significant increase in the frequency of noninfarct late gadolinium enhancement in PA (70%) when compared with essential hypertension subjects (13%; P <0.0001) with no difference in left ventricular mass. Pulse wave velocity, superoxide, and C-reactive protein were significantly higher in subjects with PA.

Conclusions—

These data illustrate that patients with PA exhibit frequent myocardial fibrosis as demonstrated by late gadolinium enhancement using cardiac magnetic resonance imaging; this finding is independent of blood pressure. This may be mediated partly through inflammation and oxidative stress. This study highlights the importance of specific targeting of aldosterone excess as well as blood pressure reduction to minimize cardiac morbidity in PA.

Effect of eplerenone on parathyroid hormone levels in patients with primary hyperparathyroidism: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Increasing evidence suggests the bidirectional interplay between parathyroid hormone and aldosterone as an important mechanism behind the increased risk of cardiovascular damage and bone disease observed in primary hyperparathyroidism. Our primary object is to assess the efficacy of the mineralocorticoid receptor-blocker eplerenone to reduce parathyroid hormone secretion in patients with parathyroid hormone excess.

METHODS/DESIGN

Overall, 110 adult male and female patients with primary hyperparathyroidism will be randomly assigned to eplerenone (25 mg once daily for 4 weeks and 4 weeks with 50 mg once daily after dose titration] or placebo, over eight weeks. Each participant will undergo detailed clinical assessment, including anthropometric evaluation, 24-h ambulatory arterial blood pressure monitoring, echocardiography, kidney function and detailed laboratory determination of biomarkers of bone metabolism and cardiovascular disease.The study comprises the following exploratory endpoints: mean change from baseline to week eight in (1) parathyroid hormone(1-84) as the primary endpoint and (2) 24-h systolic and diastolic ambulatory blood pressure levels, NT-pro-BNP, biomarkers of bone metabolism, 24-h urinary protein/albumin excretion and echocardiographic parameters reflecting systolic and diastolic function as well as cardiac dimensions, as secondary endpoints.

DISCUSSION

In view of the reciprocal interaction between aldosterone and parathyroid hormone and the potentially ensuing target organ damage, the EPATH trial is designed to determine whether eplerenone, compared to placebo, will effectively impact on parathyroid hormone secretion and improve cardiovascular, renal and bone health in patients with primary hyperparathyroidism.

TRIAL REGISTRATION

ISRCTN33941607.

Aldosterone and parathyroid hormone: a precarious couple for cardiovascular disease

Animal and human studies support a clinically relevant interaction between aldosterone and parathyroid hormone (PTH) levels and suggest an impact of the interaction on cardiovascular (CV) health. This review focuses on mechanisms behind the bidirectional interactions between aldosterone and PTH and their potential impact on the CV system. There is evidence that PTH increases the secretion of aldosterone from the adrenals directly as well as indirectly by activating the renin-angiotensin system. Upregulation of aldosterone synthesis might contribute to the higher risk of arterial hypertension and of CV damage in patients with primary hyperparathyroidism. Furthermore, parathyroidectomy is followed by decreased blood pressure levels and reduced CV morbidity as well as lower renin and aldosterone levels. In chronic heart failure, the aldosterone activity is inappropriately elevated, causing salt retention; it has been argued that the resulting calcium wasting causes secondary hyperparathyroidism. The ensuing intracellular calcium overload and oxidative stress, caused by PTH and amplified by the relative aldosterone excess, may increase the risk of CV events. In the setting of primary aldosteronism, renal and faecal calcium loss triggers increased PTH secretion which in turn aggravates aldosterone secretion and CV damage. This sequence explains why adrenalectomy and blockade of the mineralocorticoid receptor tend to decrease PTH levels in patients with primary aldosteronism. In view of the reciprocal interaction between aldosterone and PTH and the potentially ensuing CV damage, studies are urgently needed to evaluate diagnostic and therapeutic strategies addressing the interaction between the two hormones.

Hyperparathyroidism in patients with primary aldosteronism: cross-sectional and interventional data from the GECOH study

CONTEXT

Experimental studies suggest that aldosterone induces hypercalciuria and might contribute to hyperparathyroidism.

OBJECTIVE

We aimed to test for differences in PTH levels and parameters of calcium and vitamin D metabolism in patients with primary aldosteronism (PA) compared with patients with essential hypertension (EH) and to evaluate the impact of PA treatment on these laboratory values.

DESIGN, SETTING, AND PARTICIPANTS

The Graz Endocrine Causes of Hypertension study includes hypertensive patients referred for screening for endocrine hypertension at a tertiary care center in Graz, Austria.

MAIN OUTCOME MEASURES

Differences in PTH levels between patients with PA and EH.

RESULTS

Among 192 patients, we identified 10 patients with PA and 182 with EH. PTH levels (mean ± sd in picograms per milliliter) were significantly higher in PA patients compared with EH (67.8 ± 26.9 vs. 46.5 ± 20.9; P = 0.002). After treatment of PA with either adrenal surgery (n = 5) or mineralocorticoid receptor antagonists (n = 5), PTH concentrations decreased to 43.9 ± 14.9 (P = 0.023). Serum 25-hydroxyvitamin D concentrations were similar in both groups. Compared with EH, serum calcium concentrations were significantly lower (2.35 ± 0.10 vs. 2.26 ± 0.10 mmol/liter; P = 0.013), and there was a nonsignificant trend toward an increased spot urine calcium to creatinine ratio in PA [median (interquartile range) 0.19 (0.11-0.31) vs. 0.33 (0.12-0.53); P = 0.094].

CONCLUSIONS

Our results suggest that PA contributes to secondary hyperparathyroidism. Further studies are warranted to evaluate whether PTH has implications for PA diagnostics and whether mineralocorticoid receptor antagonists have a general impact on PTH and calcium metabolism.