Parathyroidectomy and blood pressure in hemodialysis patients

COMMD5 is involved in the mechanisms of hypotension after parathyroidectomy in patients receiving hemodialysis

BACKGROUND

Secondary hyperparathyroidism (SHPT) is a common complication of end-stage renal disease. Parathyroidectomy (PTx) is often employed for treatment of severe SHPT. However, PTx may cause hypotension via unknown mechanisms. COMM domain-containing protein 5 (COMMD5) in the parathyroid glands has been linked to blood pressure regulation of spontaneously hypertensive rats.

OBJECTIVE

To explore the relationship between COMMD5 levels and reduced BP after PTx in patients receiving hemodialysis (HD).

METHODS AND RESULTS

(1) The study cohort included 31 patients receiving HD who underwent PTx. Serum COMMD5 levels were higher post-PTx vs. pre-PTx. (2) Sprague-Dawley rats (n = 22) were assigned to a 5/6 nephrectomy group or sham surgery group, vascular rings of the thoracic aorta from rats with CKD were incubated with COMMD5, and changes in vascular tension were compared. COMMD5 inhibited vasoconstriction of vascular rings with intact endothelium, but had no effect on vascular rings without the endothelium. (3) Human umbilical vein endothelial cells were stimulated with COMMD5 or small interfering RNA (siRNA). The expression levels of atrial natriuretic peptide (ANP) and endothelial nitric oxide synthase (eNOS) were up-regulated and down-regulated, respectively.

CONCLUSIONS

Serum COMMD5 levels were increased after PTx in SHPT patients. COMMD5 promoted high expression of ANP and eNOS in endothelial cells, leading to vasodilation and resulting in hypotension.

Full normalization of severe hypertension after parathryoidectomy - a case report and systematic review

Background

Although the relationship between hyperparathyroidism and hypertension has been described for decades, the role of hyperparathyroidism in hypertension in dialysis is still unclear. Following the case of a severely hypertensive dialysis patient, in which parathyroidectomy (PTX) corrected the metabolic imbalance and normalized blood pressure (BP), we tried to contextualize our observation with a systematic review of the recent literature on the effect of PTX on BP.

Case presentation

A dialysis patient, aged 19 years at the time of this report, with chronic kidney disease (CKD) from childhood; he was an early-preterm baby with very low birth weight (910 g), and is affected by a so-far unidentified familial nephropathy. He started dialysis in emergency at the age of 17. Except for low-dose Bisoprolol, he refused all chronic medication; hypertension (165–200/90–130 mmHg) did not respond to attainment of dry weight (Kt/V > 1.7; BNP 70–200 pg/ml pre-dialysis). He underwent subtotal PTX 1 year after dialysis start; after PTX, his blood pressure stabilized in the 100–140/50–80 range, and is normal without treatment 5 months later.

Conclusion

Our patient has some peculiar features: he is young, has a non-immunologic disease, poor compliance to drug therapy, excellent dialysis efficiency. His lack of compliance allows observing the effect of PTX on BP without pharmacologic interference.

The prompt, complete and long-lasting BP normalization led us to systematic review the current literature (Pubmed, Embase, Cochrane Collaboration 2000–2016) retrieving 8 case series (194 cases), and one case report (3 patients).

The meta-analysis showed a significant, albeit moderate, improvement in BP after PTX (difference: systolic BP -8.49 (CI 2.21–14.58) mmHg; diastolic BP -4.14 (CI 1.45–6.84) mmHg); analysis is not fully conclusive due to lack of information on anti-hypertensive agents. The 3 cases reported displayed a sharp reduction in BP after PTX.

In summary, PTX may have a positive influence on BP control, and may result in complete correction or even hypotension in some patients. The potential clinical relevance of this relationship warrants prospective large-scale studies.

Impact of post-kidney transplant parathyroidectomy on allograft function

BACKGROUND

The impact of parathyroidectomy on allograft function in kidney transplant patients is unclear.

METHODS

We conducted a retrospective, observational study of all kidney transplant recipients from 1988 to 2008 who underwent parathyroidectomy for uncontrolled hyperparathyroidism (n = 32). Post-parathyroidectomy, changes in estimated glomerular filtration rate (eGFR) and graft loss were recorded. Cross-sectional associations at baseline between eGFR and serum calcium, phosphate, and parathyroid hormone (PTH), and associations between their changes within subjects during the first two months post-parathyroidectomy were assessed.

RESULTS

Post-parathyroidectomy, the mean eGFR declined from 51.19 mL/min/1.73 m(2) at parathyroidectomy to 44.78 mL/min/1.73 m(2) at two months (p < 0.0001). Subsequently, graft function improved, and by 12 months, mean eGFR recovered to 49.76 mL/min/1.73 m(2) (p = 0.035). Decrease in serum PTH was accompanied by a decrease in eGFR (p = 0.0127) in the first two months post-parathyroidectomy. Patients whose eGFR declined by ≥20% (group 1) in the first two months post-parathyroidectomy were distinguished from the patients whose eGFR declined by <20% (group 2). The two groups were similar except that group 1 had a higher baseline mean serum PTH compared with group 2, although not significant (1046.7 ± 1034.2 vs. 476.6 ± 444.9, p = 0.14). In group 1, eGFR declined at an average rate of 32% (p < 0.0001) during the first month post-parathyroidectomy compared with 7% (p = 0.1399) in group 2, and the difference between these two groups was significant (p = 0.0003). The graft function recovered in both groups by one yr. During median follow-up of 66.00 ± 49.45 months, 6 (18%) patients lost their graft with a mean time to graft loss from parathyroidectomy of 37.2 ± 21.6 months. The causes of graft loss were rejection (n = 2), pyelonephritis (n = 1) and chronic allograft nephropathy (n = 3). No graft loss occurred during the first-year post-surgery.

CONCLUSION

Parathyroidectomy may lead to transient kidney allograft dysfunction with eventual recovery of graft function by 12 months post-parathyroidectomy. Higher level of serum PTH pre-parathyoidectomy is associated with a more profound decrease in eGFR post-parathyroidectomy.

Acute cardiovascular effects of the calcimimetic R-568 and its enantiomer S-568 in rats

Calcimimetics increase the sensitivity of the calcium sensing receptor (CaSR) to calcium ions (Ca(2+)) and allow for efficient control of uraemic hyperparathyroidism. Recent studies suggested an additional blood pressure-lowering action, the underlying mechanisms are as yet unknown. We infused R-568 and its enantiomer S-568, which has little activity at the CaSR, in anaesthetized rats. Mean arterial blood pressure (MAP) and heart rate (HR) were measured in the femoral artery; renal blood flow (RBF) and mesenteric blood flow (MBF) were measured locally. Infusion of R-568 at 0.7 mg/kg per 10 min into the femoral vein, a dose known to reduce levels of parathyroid hormone (PTH) and Ca(2+) in plasma, did not affect blood pressure or heart rate. Infusion of 2.1 mg/kg per 3 min of R-568 and S-568 into the femoral vein significantly reduced MAP by 26 +/- 4.5 and 23.7 +/- 3.1% and HR by 7.8 +/- 2.9 and 5.8 +/- 2.0%, respectively. Intra-arterial infusions of R-568 increased blood flow in a dose-dependent fashion. At plasma concentrations of 70 micromol/l R-568 and S-568 increased RBF by 17 +/- 3 and 15 +/- 3% and MBF by 28 +/- 5 and 29 +/- 5%. The effects on blood flow were greater in the mesenteric artery than in the renal artery, but not different between both compounds.The calcimimetic R-568 exerts acute, CaSR-independent, hypotensive effects via vasodilation and negative chronotropy at concentrations exceeding those required for modulation of PTH secretion.

Survival after Parathyroidectomy in Patients with End-stage Renal Disease and Severe Hyperparathyroidism

BACKGROUND

Patients with end-stage renal disease (ESRD) and secondary hyperparathyroidism (SHPT) are at high risk of mortality. Whether an increased risk of death persists after a parathyroidectomy (PTX) is not clearly established.

SUBJECTS AND METHODS

The survival of 40 patients with ESRD and SHPT who underwent PTX was compared with that of 664 ESRD patients.

RESULTS

From first dialysis, a lower mortality rate was found in the group of patients who underwent PTX than in the nonoperated ESRD group (hazard ratio: 0.23; 95% CI: 0.14-0.37). The patients who underwent PTX were younger, had a longer time on dialysis, and had a higher prevalence of kidney transplantation. The mean number of comorbidities was lower (Charlson score 4.2 +/- 2.1 versus 6.4 +/- 2.9, p < 0.001). Then, we randomly selected two matched controls for each PTX case (80 controls, 40 PTX) who had at least an equivalent mean duration of dialysis between the first dialysis and PTX of the PTX group. In a univariate model, there was a trend for PTX being associated with prolonged survival. The mortality was higher both among those at an advanced age and those with a high Charlson score. Adjustments for these covariates made the effect of PTX no more significant.

CONCLUSIONS

The risk of death of patients with severe SHPT leading to PTX differed from that of nonoperated subjects. The apparent differences in survival may be related to the number and severity of associated comorbidities. ESRD patients who undergo PTX may represent a subset of healthier subjects.

Effectiveness of surgical parathyroidectomy for secondary hyperparathyroidism in renal dialysis patients in Qatar

Pharmacologic interventions designed to control hyperparathyroidism (HPT) in uremic patients have limitations and potentially serious adverse clinical consequences. Hence, one still has to resort to surgical parathyroidectomy (PTX) in a considerable number of dialysis patients. The aim of the present study was to illustrate our experience with 26 renal dialysis patients who underwent surgical PTX. The main indications for PTX included iPTH > 1000 pg/mL associated with severe osteitis fibrosa, debilitating pruritus, marked soft tissue calcification, or hypercalcemia with hyperphosphatemia, which sometimes complicated vitamin D therapy. All patients were resistant to more conservative measures, including control of serum phosphate, attention to oral intake and dialysate calcium levels, and oral/intravenous administration of active vitamin-D-pulse therapy. Ultrasound and technetium 99-sestamibi scan were used to image the thyroid and the parathyroid glands. Total PTX with autotransplantation was performed in 23 patients; subtotal PTX was performed in 3 patients. Histology of frozen sections taken intraoperatively showed nodular changes in 14 and diffuse hyperplasia in 12 cases. During the 2-year follow-up period significant reductions in parathyroid hormone, alkaline phospatase blood levels, skeletal changes, and soft tissue calcifications were observed. Pruritus improved in half the cases. Some improvement in hemoglobin and hematocrit was also noticed. The complication rate after PTX was low. Transient postoperative hypocalcemia requiring intensification of calcium and vitamin D therapy was seen in cases with high preoperative alkaline phosphatase levels. Recurrence was observed in two cases. Hypoparathyroidism was not recorded. We conclude that surgical reduction of parathyroid mass is a safe and effective treatment for symptomatic disease not suppressible by pharmacologic means.

The effects of parathyroidectomy on nutritional and biochemical status of hemodialysis patients with severe secondary hyperparathyroidism

The nutritional and biochemical parameters of 15 chronic hemodialysis (HD) patients with severe secondary hyperparathyroidism who had undergone total parathyroidectomy (PTX), with a forearm implant, were retrospectively studied at 1, 3, 6, and 12 months pre- and post-PTX. The concentrations of serum calcium and phosphorous significantly decreased in the first 6 months post-PTX. The concentration of blood urea nitrogen significantly increased at 6 and 12 months post-PTX. In contrast with control chronic HD patients who had no weight gain after nonparathyroid surgery, there was a progressive weight gain leading to a significantly higher dry weight at 12 months post-PTX. There was no significant change in serum potassium, albumin, cholesterol, transferrin, bicarbonate, hematocrit, normalized protein catabolic rate (nPCR), or erythropoietin dose at any time point post-PTX. The biochemical parameters of the 8 patients who had more than 5% weight gain, during 12 months post-PTX, were not statistically different from the remaining 7 cases who had weight gain less than 5% (or had lost weight) in the same time period. The same was true for 4 patients with weight gain of more than 10% versus the latter group. In conclusion, HD patients with severe secondary hyperparathyroidism are prone to progressive weight gain post-PTX, which reaches significance by the twelfth month. In 53% of the patients, the weight gain is more than 5% above the baseline. The nutritional and biochemical parameters pre-PTX were not helpful in distinguishing those who developed significant weight gain post-PTX.

Parathyroid hormone, vitamin D, and cardiovascular disease in chronic renal failure

BACKGROUND

Parathyroid hormone and vitamin D have been shown to influence cardiac and vascular growth and function experimentally in human subjects with normal renal function. Because of the increased prevalence of hyperparathyroidism and altered vitamin D status in chronic renal failure, these alterations have been considered to contribute to the increased prevalence of cardiovascular disease and hypertension seen in this patient population. Methods and Results. In this article, we review experimental and clinical literature on the cardiovascular effects of parathyroid hormone and vitamin D and relate them to the development of cardiac and vascular dysfunction in uremia, such as: cardiomyopathy, myocardial hypertrophy, and fibrosis, as well as to myocardial ischemia; uremic glucose intolerance, dyslipidemia, and atherosclerosis; hypertension; and vascular and cardiac calcifications.

CONCLUSIONS

The hyperparathyroid state and altered vitamin D status found in uremia contribute to the cardiovascular pathology seen clinically in uremia and also to the excess mortality from cardiovascular causes found in this patient group. The therapeutic implications of these observations are also discussed.

Ambulatory blood pressure monitoring in renal dialysis and transplant patients

Blood pressure (BP) elevation and left ventricular hypertrophy are important factors in the high cardiovascular mortality rate in patients on the renal replacement program. Ambulatory BP monitoring is widely regarded as superior to random BP monitoring in predicting end-organ damage from elevated BP. One hundred seventeen patients (60 on hemodialysis [35 with long sessions and 25 with short sessions], 29 on continuous ambulatory peritoneal dialysis, and 28 transplant recipients) underwent ambulatory BP monitoring, with target organ assessment by electrocardiography. Mean 24-hour BP for the patients with the long hemodialysis sessions (LHD) was 115.5/66.6 mm Hg, without the regular use of antihypertensive drugs. The parathormone (PTH) level was the major determinant of BP on ambulatory BP monitoring analysis, with interdialytic weight gain and age each having weaker associations. The BPs of the other three patient cohorts were much higher (short hemodialysis session [SHD], 143.2/82.1 mm Hg; continuous ambulatory peritoneal dialysis, 137.1/76.8 mm Hg; transplant recipients, 135.9/79.2 mm Hg). Overall, two thirds of the patients had reduced diurnal BP variability. Electrocardiogram voltage criteria for left ventricular hypertrophy were exceeded in approximately one third to one half of the patients. Our findings show that good control of BP is possible without recourse to antihypertensive drugs in the context of dialysis with slow ultrafiltration.

Blood pressure reduction after parathyroidectomy for secondary hyperparathyroidism: further evidence implicating calcium homeostasis in blood pressure regulation

A link between plasma calcium, dietary cations, and blood pressure has been suspected for some time, with human, experimental animal, and epidemiological data adduced to support this hypothesis. We identified 21 patients receiving regular maintenance hemodialysis, but not receiving any regular antihypertensive treatment, who had undergone 22 surgical removals of the parathyroid glands in the period 1978 to 1992. These patients' records were then scrutinized. The group preparathyroidectomy mean systolic blood pressure (BP) was 142.6 +/- 19.4 mm Hg. After the operation, the mean systolic BP was 133.6 +/- 21.9 mm Hg (P = 0.004). Plasma calcium decreased from 2.72 +/- 0.18 mmol/L to 2.52 +/- 0.19 mmol/L (P < 0.001). There was a correlation between the decreases in systolic blood pressure (SBP) (9.4%) and plasma calcium (7.3%); r = 0.60, P = 0.012. The decrease in SBP was not immediate, but delayed some months and complete by approximately 9 months after the operation. Furthermore, using ambulatory BP monitoring in a group of long-term hemodialysis patients, we found that parathyroidectomized patients had lower BP and pulse rates than those with intact parathyroid glands (SBP, 122.9 +/- 16.3 mm Hg v 102.9 +/- 9.9 mm Hg; pulse rates, 87.5 +/- 12.7 v 72.0 +/- 7.5 beats/min, P < .001, nonparathyroidectomy v postparathyroidectomy, both comparisons). These data support a link between plasma calcium and BP in patients receiving maintenance hemodialysis.