PTH: Potential role in management of heart failure

Vitamin D-Parathyroid Hormone-Fibroblast Growth Factor 23 Axis and Cardiac Remodeling

Cardiac remodeling is a compensatory adaptive response to chronic heart failure (HF) altering the structure, function, and metabolism of the heart. Many nutritional and metabolic diseases can aggravate the pathophysiological development of cardiac remodeling. Vitamin D deficiency leads to cardiac remodeling by activating the renin-angiotensin-aldosterone system (RAAS), resulting in enhanced inflammation and directly promoting cardiac fibrosis and extracellular matrix deposition. Hyperparathyroidism upregulates protein kinase A or protein kinase C, enhances intracellular calcium influx, promotes oxidative stress, activates RAAS, and increases aldosterone levels, thereby aggravating cardiac remodeling. Besides, fibroblast growth factor 23 (FGF23) plays a direct role in the heart, resulting in ventricular hypertrophy and myocardial fibrosis. Vitamin D deficiency leads to hyperparathyroidism, which in turn increases the level of FGF23. Elevated levels of FGF23 further inhibit vitamin D synthesis. Evidence exists that vitamin D deficiency, hyperparathyroidism, and marked elevations in FGF23 concentration form a vicious cycle and are believed to contribute directly to cardiac remodeling. Therefore, the purpose of this article is to introduce the specific effects of the above substances on the heart and to explain the significance of understanding the vitamin D-parathyroid hormone-FGF23 axis in improving or even reversing cardiac remodeling, thus contributing to the treatment of patients with HF.

The Association between Admission Serum Phosphorus and Preoperative Deep Venous Thrombosis in Geriatric Hip Fracture: A Retrospective Study

OBJECTIVE

This study aimed to evaluate the association between serum phosphorus level and preoperative deep vein thrombosis (DVT) in geriatric hip fractures.

METHODS

Older adults with hip fractures were screened between January 2015 and September 2019. Demographic and clinical characteristics of the patients were collected. Multivariate binary logistic regression and generalized additive models were used to identify the linear and nonlinear associations between serum phosphorus levels and preoperative DVT. Analyses were performed using Empower Stats and R software.

RESULTS

In this study, 1818 patients were included, with an average age of 79.39 ± 6.87. Of these, 30.25% were males, and 580 patients had DVT. The study found that when serum phosphorus was used as a continuous variable, there was a statistically significant difference in the relationship between blood phosphorus and the occurrence of DVT (p < 0.05). Furthermore, we also found curvilinear relationships. Serum phosphorus = 0.71 mmol/L was the inflection point in the curve. When serum phosphorus was <0.71 mmol/L, the serum phosphorus was associated with DVT (OR = 1.64; 95% CI: 1.04-2.59; p = 0.0333). With a 0.1 mmol/L increase, the DVT increased 0.64 times. When phosphorus was >0.71 mmol/L, there was no significant difference in the correlation between serum phosphorus levels and DVT (OR = 1.03; 95% CI: 0.98-1.09; p = 0.186).

CONCLUSION

Serum phosphorus was nonlinearly associated with preoperative DVT in geriatric patients with hip fractures, and serum phosphorus level could be considered a predictor of DVT risk.

Calcium-Regulating Hormonal System and HMGB1 in Cardiomyopathies

BACKGROUND

Calcium ions play a key role in the heart's functional activity. The steadystate levels of calcium are contingent on the calcium regulating hormonal system, impairment of which might result in the development of cardiac pathology. An important role in these processes is also attributed to the specific inflammatory mediator, HMGB1, one of the damage-associated molecular patterns (DAMPs) released by immune cells or cell damage.

OBJECTIVE

This study investigated the cardioprotective potential of the calcium-regulating hormonal system in cardiomyopathies with an emphasis on the possible role of HMGB1.

METHODS

Ca2+ and inorganic phosphate levels were determined in the serum using an electrolyte analyzer and spectrophotometric analyzer correspondingly. The 1-34 fragment of parathyroid hormone (PTH), calcitonin, vitamin D, and HMGB1 were detected using ELISA kits.

RESULTS

The levels of PTH, calcitonin, phosphate, and HMGB1 were found elevated in females suffering from cardiomyopathy. The same tendency was observed in men; however, statistically significant changes were registered only for PTH and phosphate.

CONCLUSION

It can be suggested that among other reasons, the decrease of the left ventricular function in cardiomyopathy patients can be linked to the high HMGB1, whereas the activation of the calciumregulating system as manifested by the elevated PTH aims at restoration of calcium homeostasis and thus have positive, i.e. cardioprotective consequences.

Plasma Levels of Intact Parathyroid Hormone and Congestion Burden in Heart Failure: Clinical Correlations and Prognostic Role

Circulating parathyroid hormone (PTH) concentrations increase in heart failure (HF) and are related to disease severity. The relationship between PTH and congestion is still a matter of debate. The objective of this analysis was to evaluate the role of PTH as a marker of congestion and prognosis in HF. We enrolled 228 patients with HF. Intact PTH concentrations and HYDRA score (constituted by: B-type natriuretic peptide, blood urea nitrogen−creatinine ratio, estimated plasma volume status, and hydration status) were evaluated. The study endpoint was all-cause mortality. PTH levels were higher in acute compared with chronic HF and in patients with clinical signs of congestion (i.e., peripheral oedema and orthopnea). PTH concentrations significantly correlated with NYHA class and HYDRA score. At multivariate analysis of HYDRA score, estimated glomerular filtration rate (eGFR), and corrected serum calcium were independently determinants of PTH variability. Fifty patients (22%) died after a median follow-up of 408 days (interquartile range: 283−573). Using univariate Cox regression analysis, PTH concentrations were associated with mortality (hazard ratio [HR]: 1.003, optimal cut-off: >249 pg/mL—area under-the-curve = 0.64). Using multivariate Cox regression analysis, PTH was no longer associated with death, whereas HYDRA score, left ventricular ejection fraction, and eGFR acted as independent predictors for mortality (HR: 1.96, 0.97, and 0.98, respectively). Our study demonstrated that intact PTH was related to clinical and subclinical markers of congestion. However, intact PTH did not act as an independent determinant of all-cause death in HF patients.

Effect of vitamin D on endothelial and ventricular function in chronic heart failure patients: A prospective, randomized, placebo-controlled trial

BACKGROUND

Low 25-hydroxyvitamin D (25OHD) levels are common in patients with chronic heart failure (HF) and are associated with increased mortality risk. This study aimed to establish the safety and efficacy of oral vitamin D3 (cholecalciferol) supplementation and its effect on endothelial and ventricular function in patients with stable HF.

METHODS

This study was an investigator-initiated, multicenter, prospective, randomized, placebo-controlled trial. Seventy-three HF patients with 25OHD levels < 75 nmol/L (30 ng/mL) were randomized to receive 4000 IU vitamin D daily or a placebo for 6 months. The primary endpoint was a change in endothelial function between the baseline and after 6 months as assessed using EndoPAT. Secondary endpoints included changes in echocardiographic parameters and differences in quality of life (6-min walking test and New York Heart Association functional status) at 6 months.

RESULTS

There were no adverse events in either group during the study period. Vitamin D supplementation did not improve endothelial dysfunction (EndoPAT: baseline, 1.19 ± 0.4 vs 6 months later, 1.22 ± 0.3, P = .65). However, patients' blood pressure, 6-min walking distance, and EQ-5D questionnaire scores improved after vitamin D treatment. In addition, a significant reduction in the left atrial diameter was observed.

CONCLUSION

A daily vitamin D dose of 4000 IU for chronic HF appears to be safe. This dosage did not improve endothelial function but did improve the 6-min walk distance, symptoms, and left atrial diameter at 6 months.

Sex-Specific Relationship Between Parathyroid Hormone and Platelet Indices in Phenotypes of Heart Failure-Results From the MyoVasc Study

Background: Heart failure (HF) is a multifactorial syndrome with pathophysiological complexities still not fully understood. Higher mean platelet volume (MPV), a potential marker of platelet activation, and high concentrations of parathyroid hormone (PTH) have been implicated in the pathogenesis of HF.

Aim: This study aims to investigate sex-specifically the association between PTH concentrations and platelet indices in phenotypes of HF.

Methods and Results: PTH and platelet indices (MPV and platelet count) were available in 1,896 participants from the MyoVasc study in Mainz, Germany. Multivariable linear regression models, adjusted for age, sex, season, vitamin D status, cardiovascular risk factors, comorbidities, estimated glomerular filtration rate, and medication, were used to assess the associations between platelet indices and PTH. The results showed distinct sex-specific associations between PTH and platelet indices. A positive association between PTH and MPV was found in females with symptomatic HF with reduced ejection fraction (HFrEF) only [β = 0.60 (0.19; 1.00)]. Platelet count was inversely associated with PTH in male HFrEF individuals [β = −7.6 (−15; −0.30)] and in both males and females with HF with preserved ejection fraction (HFpEF).

Conclusion: This study reports differential, sex-specific relationships between PTH and platelet indices in HF individuals independent of vitamin D status and clinical profile. Particularly in phenotypes of symptomatic HF, distinct associations were observed, suggesting a sex-specific mechanism involved in the interaction between PTH and platelets.

Increasing Age Hinders the Decline in B-Type Natriuretic Peptide Following Parathyroidectomy in Dialysis Patients

BACKGROUND/AIM

Parathyroidectomy has beneficial effects on all-cause and cardiovascular mortality in patients with uncontrolled hyperparathyroidism. B-Type natriuretic peptide (BNP) correlates with the severity of heart failure. We aimed to investigate whether parathyroidectomy modulates the BNP levels in dialysis patients.

PATIENTS AND METHODS

Patients who underwent surgical intervention for hyperparathyroidism were included. The serum BNP levels were determined before parathyroidectomy and during follow-up.

RESULTS

The preoperative and postoperative BNP levels were 499±561 and 453±442 pg/ml, respectively (p=0.82). The baseline BNP level was positively correlated with weakness and headache, but not biochemical parameters. In multivariate analysis, age (odds ratio=0.837) and preoperative symptom score (odds ratio=0.935) were independent predictors for the postoperative decline in BNP levels Conclusion: The serum BNP levels may increase or decrease after parathyroidectomy. Younger age and lower symptom burden are associated with decline in BNP levels.

Meta-analysis of vitamin D supplementation in the treatment of chronic heart failure

Objectives. We performed a meta-analysis to determine whether vitamin D supplementation is beneficial in patients with chronic heart failure (CHF). Design. Meta-analysis of randomised controlled trials. Results. Vitamin D supplementation in patients with CHF improved health-related quality of life and C-reactive protein levels [weighted mean difference (WMD): 6.75, 95% confidence interval (CI): 2.87 to 10.64, p < .001; standardised mean difference (SMD): -0.41, 95% CI: -0.71 to -0.11, p = .007]. However, this supplementation was not superior to conventional treatment in terms of mortality, changes in left ventricular ejection fraction (ΔLVEF), N-terminal pro-B-type natriuretic peptide or B-type natriuretic peptide levels, and 6-minute walk distance (risk ratio: 1.11, 95% CI: 0.79 to 1.57, p = .53; WMD: 2.56, 95% CI: -2.18 to 7.31, p = .29; SMD: -0.18, 95% CI: -0.42 to 0.06, p = .15; WMD: -23.30, 95% CI: -58.31 to 11.72, p = .19). In contrast, ΔLVEF significantly improved (WMD: 6.75, 95% CI: 4.16 to 9.34, p < .001) in the subgroup without calcium supplementation. Additionally, some randomised controlled trials showed that adverse events were more frequent in people with high vitamin D levels. Conclusions. Vitamin D supplementation decreases serum levels of inflammatory markers and improves quality of life in CHF patients. Pooled analysis of vitamin D supplementation did not show reduced mortality or improved left ventricular function perhaps because of excessive increase in plasma 25-hydroxyvitamin D and calcium levels. Future studies should pay attention to vitamin D and calcium levels achieved.

Effects of Altered Calcium Metabolism on Cardiac Parameters in Primary Aldosteronism

BACKGROUND

Increasing evidence supports interplay between aldosterone and parathyroid hormone (PTH), which may aggravate cardiovascular complications in various heart diseases. Negative structural cardiovascular remodeling by primary aldosteronism (PA) is also suspected to be associated with changes in calcium levels. However, to date, few clinical studies have examined how changes in calcium and PTH levels influence cardiovascular outcomes in PA patients. Therefore, we investigated the impact of altered calcium homeostasis caused by excessive aldosterone on cardiovascular parameters in patients with PA.

METHODS

Forty-two patients (mean age 48.8±10.9 years; 1:1, male:female) whose plasma aldosterone concentration/plasma renin activity ratio was more than 30 were selected among those who had visited Severance Hospital from 2010 to 2014. All patients underwent adrenal venous sampling with complete access to both adrenal veins.

RESULTS

The prevalence of unilateral adrenal adenoma (54.8%) was similar to that of bilateral adrenal hyperplasia. Mean serum corrected calcium level was 8.9±0.3 mg/dL (range, 8.3 to 9.9). The corrected calcium level had a negative linear correlation with left ventricular end-diastolic diameter (LVEDD, ρ=-0.424, P=0.031). Moreover, multivariable regression analysis showed that the corrected calcium level was marginally associated with the LVEDD and corrected QT (QTc) interval (β=-0.366, P=0.068 and β=-0.252, P=0.070, respectively).

CONCLUSION

Aldosterone-mediated hypercalciuria and subsequent hypocalcemia may be partly involved in the development of cardiac remodeling as well as a prolonged QTc interval, in subjects with PA, thereby triggering deleterious effects on target organs additively.

Working Toward an Improved Understanding of Chronic Cardiorenal Syndrome Type 4

Chronic diseases of the heart and of the kidneys commonly coexist in individuals. Certainly combined and persistent heart and kidney failure can arise from a common pathologic insult, for example, as a consequence of poorly controlled hypertension or of severe diffuse arterial disease. However, strong evidence is emerging to suggest that cross talk exists between the heart and the kidney. Independent processes are set in motion when kidney function is chronically diminished, and these processes can have distinct adverse effects on the heart. The complex chronic heart condition that results from chronic kidney disease (CKD) has been termed cardiorenal syndrome type 4. This review will include an updated description of the cardiac morphology in patients who have CKD, an overview of the most likely CKD-sourced culprits for these cardiac changes, and the potential therapeutic strategies to limit cardiac complications in patients who have CKD.

The Role of Parathyroid Hormone and Vitamin D Serum Concentrations in Patients with Cardiovascular Diseases

25-hydroxyvitamin D (25(OH)D) plays a crucial role in human homeostasis. Its deficiency (vitamin D deficiency—VDD), being common in European population, combined with elevated concentration of parathyroid hormone (PTH), represents a vicious cycle of mechanisms leading to heart failure (HF). Despite several papers published in that field, the effect of VDD and PTH concentration on cardiovascular system remains unequivocal; thus, the aim of the study was to compare these data among HF and non-HF patients being prospectively enrolled into the study during hospital stay in the cardiology ward. Patients with HF had higher PTH concentration (85.0 ± 52.6 versus 64.5 ± 31.7, p ≤ 0.02) compared to non-HF patients. Mean PTH values were associated with the clinical status expressed by the New York Heart Association class (NYHA class) (“0”—66.04, “I”—56.57, “II”—72.30, “III”—85.59, and “IV”—144.37 pg/ml, p ≤ 0.00004). Interestingly, neither 25(OH)D (31.5 versus 29.7 ng/ml, p ≤ ns) nor phosphorus (P) (1.23 versus 1.18 mmol/l, p ≤ ns) nor total calcium (Ca²⁺) concentration (2.33 versus 2.37 mmol/l, p ≤ ns) differed among the groups. Reassuming PTH serum concentration in contrary to 25(OH)D, P and Ca²⁺ are significantly raised among the patients with HF and shows significant relationship with the clinical status expressed by the NYHA class.

Elevation of plasma oncostatin M in heart failure

Aim: Oncostatin M (OSM) is an inflammatory cytokine of the gp130 family. OSM could participate in adverse cardiovascular remodeling through regulation of FGF23. Materials & methods: OSM levels were determined in 80 heart failure patients with reduced left ventricular ejection fraction (HFrEF). Results: OSM levels are significantly increased in HFrEF patients compared with healthy subjects. We have also demonstrated that, in HFrEF patients, plasma OSM levels are correlated to parathyroid hormone PTH(1–84) and 1,25(OH)2D, two other biomarkers related to bone and mineral metabolism and associated to adverse cardiovascular outcomes. Conclusion: OSM concentrations are elevated in HFrEF patients and could interplay with parathyroid hormone and vitamin D impacting cardiovascular function. Nevertheless, the prognostic value of OSM testing appears limited.

Secondary hyperparathyroidism prevalence and prognostic role in elderly males with heart failure

AIM

Evaluation of secondary hyperparathyroidism (SHPT) and its prognostic impact on all-cause mortality in elderly males with heart failure (HF).

METHODS

Seventy three males (67 ± 7 years old) with systolic HF were included. Baseline PTH was measured. Patients were grouped according to PTH cut-off levels of 65 pg/ml (>65 pg/ml = SHPT vs. normal PTH). All-cause mortality was evaluated at 6-year follow-up.

RESULTS

SHPT was diagnosed in 43 (59 %) patients. They were more severe compared to the patients with normal PTH regarding NYHA functional class (2.4 ± 0.5 vs. 2.1 ± 0.2, p = 0.001), quality of life score (34 ± 14 vs. 24 ± 12, p = 0.005), 6-min walking distance (378 ± 79 vs. 446 ± 73 m, p < 0.0001), left ventricular ejection fraction (27 ± 8 vs. 31 ± 7 %, p = 0.019), and NT-proBNP [2452 (3399) vs. 918 (1372) pg/ml, p < 0.0001]. No differences in age, vitamin D status, and renal function were noted between studied groups. A total of 41 (56 %) patients died within 6 years of follow-up. Kaplan-Meier survival analysis showed impaired long-term survival in patients with SHPT versus patients with normal PTH (p = 0.009). The rate of death was highest (75 %) in the group of patients with SHPT and NT-proBNP levels above median value (p = 0.003). Cox regression analysis demonstrated that NT-proBNP was the single independent predictor of all-cause mortality at 6-year follow-up [HR 3.698 (1.927-7.095), p < 0.0001].

CONCLUSION

SHPT was highly prevalent in elderly males with HF and was associated with impaired survival. HF patients with SHPT had more severe disease compared to the patients with normal serum PTH. Determination of serum PTH levels provided additional value to NT-proBNP for risk stratification in these patients.

Policosanol as a new inhibitor candidate for vascular calcification in diabetic hyperlipidemic rats

This work mainly aimed to investigate the probable changes of aortic calcification by policosanol, omega-3 fatty acids in comparison with atorvastatin and subsequent progression of atherosclerosis in diabetic hyperlipemic rat model. Adult male albino rats of wistar strain (30) were divided into five groups (n = 6/group); one was fed normal diet and was used as a normal group, the other groups received alloxan, atherogenic diet (CCT - rat chow diet supplemented with 4% cholesterol, 1% cholic acid, and 0.5% thiouracil) and categorized as follows: the second group received no treatment and kept as control (diabetic hyperlipidemic control group (DHC)). The other groups received daily oral doses of atorvastatin, policosanol (10 mg/kg body weight) and ω-3 (50 mg/kg body weight), respectively, for eight weeks. Different biomarkers were used for the evaluation that included inflammatory (C reactive protein (CRP), tumor necrosis factor α (TNF-α)), oxidative stress (glutathione (GSH), malondialdehyde (MDA)) bone calcification markers (alkaline phosphatase (ALP), Vitamin D, parathyroid hormone (PTH)), lipogram pattern in addition to histochemical demonstration of calcium in the aorta. Diabetic hyperlipemic group demonstrated significant hyperglycemia, hyperlipidemia, and increased inflammation, oxidative stress, calcification, and finally atherogenesis progression. Treatment of diabetic hyperlipemic rats with, policosanol, omega-3 fatty acids (natural products) and atorvastatin for eight weeks significantly increased high-density lipoprotein cholesterol (HDL-C), Vitamin D, decreased aortic vacuoles number, and inhibited calcification process. Policosanol induced more remarkable reduction in the density and number of foam cells and improved the intimal lesions of the aorta as compared to atorvastatin. Drugs under study exerted hypoglycemic effect along with an inhibition of inflammation, oxidative stress, and calcium deposition with certain variations but policosanol effect was remarkable in comparison with other drugs.

Parathyroid hormone and risk of heart failure in the general population: A meta-analysis of prospective studies

Inconsistent findings have been reported on the association between the parathyroid hormone (PTH) level and risk of heart failure. We aimed to systematically evaluate the association between circulating level of PTH and risk of heart failure in the general population by conducting a meta-analysis. We made a comprehensive literature search in PubMed, Embase, VIP, CNKI, and Wanfang databases published until January 2016. Only prospective observational studies reporting the association between circulating level of PTH and risk of heart failure in the general population were selected. Pooled adjusted hazard ratio (HR) and corresponding 95% confidence intervals (CIs) were calculated for the highest versus lowest PTH category. Six studies with 25,207 participants identified. Higher circulating level of PTH was associated with an increased risk of heart failure (HR: 1.38; 95% CI 1.09-1.74) in a random effect model. Subgroup analyses revealed that the risk of heart failure was more pronounced among men (HR: 1.75; 95% CI 1.38-2.22) than in both genders. However, the risk increment was not statistically significant (HR: 1.12; 95% CI 0.76-1.66) in the middle-aged population. Higher PTH level is independently associated with an exacerbated risk of heart failure in the general population.

Acute effects of low-level laser therapy irradiation on blood lactate and muscle fatigue perception in hospitalized patients with heart failure-a pilot study

The objective of the present study is to evaluate the acute effects of low-level laser therapy (LLLT) on functional capacity, perceived exertion, and blood lactate in hospitalized patients with heart failure (HF). Patients diagnosed with systolic HF (left ventricular ejection fraction <45 %) were randomized and allocated prospectively into two groups: placebo LLLT group (n = 10)-subjects who were submitted to placebo laser and active LLLT group (n = 10)-subjects who were submitted to active laser. The 6-min walk test (6MWT) was performed, and blood lactate was determined at rest (before LLLT application and 6MWT), immediately after the exercise test (time 0) and recovery (3, 6, and 30 min). A multi-diode LLLT cluster probe (DMC, São Carlos, Brazil) was used. Both groups increased 6MWT distance after active or placebo LLLT application compared to baseline values (p = 0.03 and p = 0.01, respectively); however, no difference was observed during intergroup comparison. The active LLLT group showed a significant reduction in the perceived exertion Borg (PEB) scale compared to the placebo LLLT group (p = 0.006). In addition, the group that received active LLLT showed no statistically significant difference for the blood lactate level through the times analyzed. The placebo LLLT group demonstrated a significant increase in blood lactate between the rest and recovery phase (p < 0.05). Acute effects of LLLT irradiation on skeletal musculature were not able to improve the functional capacity of hospitalized patients with HF, although it may favorably modulate blood lactate metabolism and reduce perceived muscle fatigue.

Serum Parathyroid Hormone Levels Predict Discharge and Readmission for Heart Failure

AIMS

Parathyroid hormone (PTH) levels are useful as a prognostic factor of chronic heart failure (HF) and can predict hospitalization for HF. It is unknown whether serum PTH levels in hospitalized patients with HF can predict discharge and if admission, discharge, or change from admission to discharge PTH measure is the most important predictor of readmission and/or death.

METHODS

A total of 125 consecutive hospitalized patients with HF were enrolled into this study. The receiver operating characteristic (ROC) curves indicated the predicted values of PTH for readmission due to HF and the optimal cutoff points of PTH levels for discharge. The binary logistic regression model indicated an association between PTH levels and readmission due to HF.

RESULTS

The PTH level on admission was positively correlated with the New York Heart Association class and N-terminal pro-B-type natriuretic peptide level. The ROC curves showed that the PTH level at discharge (PTHdis) was of predictive value for readmission within 1 year due to HF. A PTHdis level <45.2 pg/mL was the best cutoff point for discharge, with a sensitivity of 72.1%, specificity of 61.5%, and area under the ROC curve of 0.693 (95% confidence interval [CI] 0.598-0.788). The results of logistic regression analysis showed that PTHdis had an odds ratio of 1.035 for readmission due to HF (95% CI 1.005-1.067).

CONCLUSION

Serum PTH levels in hospitalized patients with HF were shown to be an independent predictor of discharge and PTHdis was the best predictor of readmission and/or death within 1 year due to HF.

PTH and Vitamin D

PTH and Vitamin D are two major regulators of mineral metabolism. They play critical roles in the maintenance of calcium and phosphate homeostasis as well as the development and maintenance of bone health. PTH and Vitamin D form a tightly controlled feedback cycle, PTH being a major stimulator of vitamin D synthesis in the kidney while vitamin D exerts negative feedback on PTH secretion. The major function of PTH and major physiologic regulator is circulating ionized calcium. The effects of PTH on gut, kidney, and bone serve to maintain serum calcium within a tight range. PTH has a reciprocal effect on phosphate metabolism. In contrast, vitamin D has a stimulatory effect on both calcium and phosphate homeostasis, playing a key role in providing adequate mineral for normal bone formation. Both hormones act in concert with the more recently discovered FGF23 and klotho, hormones involved predominantly in phosphate metabolism, which also participate in this closely knit feedback circuit. Of great interest are recent studies demonstrating effects of both PTH and vitamin D on the cardiovascular system. Hyperparathyroidism and vitamin D deficiency have been implicated in a variety of cardiovascular disorders including hypertension, atherosclerosis, vascular calcification, and kidney failure. Both hormones have direct effects on the endothelium, heart, and other vascular structures. How these effects of PTH and vitamin D interface with the regulation of bone formation are the subject of intense investigation.

1,25-Dihydroxyvitamin D to PTH(1-84) Ratios Strongly Predict Cardiovascular Death in Heart Failure

OBJECTIVES

Vitamin D deficiency and hyperparathyroidism are common in patients with heart failure (HF). There is a growing body of evidence supporting the role of vitamin D and parathyroid hormone (PTH) in cardiac remodeling and worsening of HF. Lack of reliable automated testing of 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active metabolite of vitamin D, has limited its contribution to the prognostic assessment of HF. Here, the association of 1,25(OH)2D and PTH(1-84) levels was evaluated for prediction of cardiovascular death in chronic HF patients.

METHODS

We conducted a single center prospective cohort including 170 chronic HF patients (females n = 36; males n = 134; NYHA II-IV; mean age: 67 years; etiology: ischemic n = 119, dilated cardiomyopathy n = 51; mean LVEF: 23%). The primary outcome was cardiovascular death.

RESULTS

Serum levels of 1,25(OH)2D decreased markedly with increased HF severity. Medians were 33.3 pg/mL for NYHA-II patients, 23.4 pg/mL for NYHA-III, and 14.0 pg/mL for NYHA-IV patients (p<0.001). Most patients had levels of 25(OH)D below 30ng/mL, and stratification by NYHA functional class did not show significant differences (p = 0.249). The 1,25(OH)2D to PTH(1-84) ratio and the (1,25(OH)2D)2 to PTH(1-84) ratio were found to be the most significantly related to HF severity. After a median follow-up of 4.1 years, 106 out of 170 patients reached the primary endpoint. Cox proportional hazard modeling revealed 1,25(OH)2D and the 1,25(OH)2D to PTH(1-84) ratios to be strongly predictive of outcomes.

CONCLUSIONS

1,25(OH)2D and its ratios to PTH(1-84) strongly and independently predict cardiovascular mortality in chronic HF.

Effects of sun exposure and dietary vitamin D intake on serum 25-hydroxyvitamin D status in hemodialysis patients

BACKGROUND/OBJECTIVES

Vitamin D deficiency is common in hemodialysis patients. The aim of this study was to identify whether or not sun exposure and dietary vitamin D intake have effects on serum 25-hydroxyvitamin D (25(OH)D) status in hemodialysis (HD) patients. The objective was to identify the main determinants of serum vitamin D status in the study subjects.

SUBJECTS/METHODS

A cross-sectional study of 47 HD patients (19 males and 28 females) was performed. We assessed serum 25(OH)D and 1,25(OH)₂D levels between August and September 2012 and analyzed the prevalence of vitamin D deficiency in HD patients. To evaluate the determinants of serum 25(OH)D levels, we surveyed dietary vitamin D intake, degree of sun exposure, and outdoor activities. To compare biological variables, serum 25(OH)D was stratified as below 15 ng/ml or above 15 ng/ml.

RESULTS

Mean 25(OH)D and 1,25(OH)₂D levels were 13.5 ± 5.8 ng/ml and 20.6 ± 11.8 pg/ml, respectively. The proportions of serum 25(OH)D deficiency (< 15 ng/ml), insufficiency (15-< 30 ng/ml), and sufficiency (≥ 30 ng/ml) in subjects were 72.4%, 23.4%, and 4.3%, respectively. Prevalence of vitamin D deficiency in female patients was 78.6%, whereas that in males was 63.2% (P = 0.046). Vitamin D intake and sun exposure time were not significantly different between the two stratified serum 25(OH)D levels. Dietary intake of vitamin D did not contribute to increased serum 25(OH)D levels in HD patients. The main effective factors affecting serum 25(OH)D status were found to be the sun exposure and active outdoor exercise.

CONCLUSIONS

Hypovitaminosis D is common in HD patients and is higher in females than in males. Sun exposure is the most important determinant of serum 25(OH)D status in HD patients.

Pathophysiology and the cardiorenal connection in heart failure. Circulating hormones: biomarkers or mediators

Heart failure (HF) is a syndrome characterized by a complex pathophysiology which involves multiple organ systems, with the kidney playing a major role. HF can present with reduced ejection fraction (EF), HFrEF, or with preserved EF (HFpEF). The interplay between diverse organ systems contributing to HF is mediated by the activation of counteracting neurohormonal pathways focused to re-establishing hemodynamic homeostasis. During early stages of HF, these biochemical signals, consisting mostly of hormones and neurotransmitters secreted by a variety of cell types, are compensatory and the patient is asymptomatic. However, with disease progression, the attempt to reverse or delay cardiac dysfunction is deleterious, leading to multi-organ congestion, fibrosis and decompensation and finally symptomatic HF. In conclusion, these neurohormonal pathways mediate the evolution of HF and have become a way to monitor HF. Specifically, these mediators have become important in the diagnosis and prognosis of this highly fatal cardiovascular disease. Finally, while these multiple neurohumoral factors serve as important HF biomarkers, they can also be targeted for more effective and curative HF treatments.