Changes in blood pressure and renal function after parathyroidectomy in primary hyperparathyroidism

Clinical features of sporadic multigland parathyroid disease

Background. Sporadic multigland parathyroid disease (MGD) account for 1/4 of all cases of primary hyperparathyroidism (PHPT). There are no specific signs of MGD in comparison with single-gland parathyroid disease in PHPT. The only radical treatment is surgical, therefore, determining the number of excessively functioning parathyroid glands at the preoperative stage is important for choosing the extent of the operation and the success of the treatment in general.The aim. To identify the specific signs of multigland parathyroid disease in patients who underwent surgery for primary hyperparathyroidism. Methods. We conducted a single-center prospective study including 126 cases of surgical treatment of PHPT from December 2019 to June 2021. The study included an analysis of demographic, clinical, laboratory parameters and visual methods of topical diagnosis of parathyroid glands (ultrasound, scintigraphy, multislice computed tomography). The main endpoint of the study was the identification of characteristic signs of MGD in patients with PHPT.Results. Lower values of creatinine (p ≤ 0.01; Mann – Whitney U-test), albuminadjusted calcium (p ≤ 0.05; Mann – Whitney U-test), parathyroid hormone (p ≤ 0.01; Mann – Whitney U-test), glomerular filtration rate (p ≤ 0.01; Mann – Whitney U-test) and inconsistency of two methods of preoperative imaging (p ≤ 0.01; χ2) were set as specific signs of multigland compared with single-gland parathyroid disease. Conclusion. The results of preoperative biochemical and imaging studies can become the basis for differentiating single-gland and multigland parathyroid disease in primary hyperparathyroidism.

The effect of parathyroidectomy compared to non-surgical surveillance on kidney function in primary hyperparathyroidism: a nationwide historic cohort study

BACKGROUND

Patients with primary hyperparathyroidism (pHPT) and impaired kidney function (estimated glomerular filtration rate (eGFR) < 60 mL/min) are offered parathyroidectomy (PTX) to protect them from further complications. Surprisingly, two recent uncontrolled cohort studies have suggested a further decrease in kidney function following PTX. We aimed to examine the effects of PTX compared to non-surgical surveillance on kidney function in pHPT patients.

METHODS

Historic cohort study. From the Danish National Patient Registry (NPR) and major medical biochemistry laboratories in Denmark, we identified 3585 patients with biochemically confirmed pHPT among whom n = 1977 (55%) were treated with PTX (PTX-group) whereas n = 1608 (45%) were followed without surgery (non-PTX group). Baseline was defined as time of diagnosis and kidney function was re-assessed 9-15 months after PTX (PTX group) or 9-15 months after diagnosis (non-PTX group).

RESULTS

At follow-up, eGFR had decreased significantly in the PTX- compared to the non-PTX-group (median - 4% vs. - 1%, p < 0.01). Stratification by baseline eGFR showed that the decrease was significant for those with a baseline eGFR value of 80-89 and > 90 mL/min, but not for those with lower eGFR values. Findings did not differ between patients with mild compared to moderate/severe hypercalcemia. However, after mutual adjustments, we identified baseline levels of calcium, PTH, and eGFR as well as age and treatment (PTX vs. no-PTX) as independent predictors for changes in kidney function.

CONCLUSION

Compared to non-surgical surveillance, PTX is associated with a small but significant decrease in kidney function in pHPT patients with an initial normal kidney function.

Independent effects of secondary hyperparathyroidism and hyperphosphatemia on chronic kidney disease progression and cardiovascular events: an analysis from the NEFRONA cohort

BACKGROUND

Secondary hyperparathyroidism (SHPT) is a complication of chronic kidney disease (CKD), and it is associated with changes in calcium and phosphate. These related changes have been associated with increased cardiovascular mortality and CKD progression. It is not clear whether negative outcomes linked to SHPT are confounded by such factors. The present study was designed to assess the possible independent effects of SHPT (defined as patients with excessive PTH levels or on treatment with PTH reducing agents) on the risk of CKD progression and CVE incidence in CKD patients, as well as whether hypercalcemia and/or hyperphosphatemia act as effect modifiers.

METHODS

The study enrolled 2445 CKD patients without previous CVE from the NEFRONA cohort (950 stage 3, 612 stage 4, 195 stage 5 and 688 on Dialysis). Multivariate logistic and Fine and Gray regression analysis were used to determine the risk of patients of suffering CKD progression or a CVE.

RESULTS

Prevalence of SHPT in the whole cohort was 65.6% (CKD 3 54.7%; CKD 4 74.7%; CKD 5 71.4%; Dialysis 68.6%). After 2-years, 301 patients presented CKD progression. During 4-years follow-up, 203 CVE were registered. Patients with SHPT showed a higher adjusted risk for CKD progression and CVE. Furthermore, hyperphosphatemia was shown to be an independent risk factor in both outcomes and did not modify SHPT effect. No significant interactions were detected between the presence of SHPT and hypercalcemia or hyperphosphatemia.

CONCLUSIONS

We conclude that SHPT and hyperphosphatemia are independently associated with CKD progression and the incidence of CVE in CKD patients.

The influence of parathyroidectomy on cardiometabolic risk factors in patients with primary hyperparathyroidism: a systematic review and meta-analysis

PURPOSE

Primary hyperparathyroidism (PHPT) is associated with increased risk of cardiovascular morbidity and mortality. We aim to determine whether parathyroidectomy (PTX) can change cardiometabolic risk factors including serum lipids, glycemic parameters, systolic and diastolic blood pressure, C reactive protein (CRP), and body mass index (BMI).

METHODS

MEDLINE, Web of Science, Scopus, and Google Scholar were searched for relevant articles published till June 2020. Fixed-effect or random-effects models were used to estimate the weighted mean difference (WMD) and 95% CI for outcomes where applicable.

RESULTS

In total, 34 studies were eligible to be included in the current meta-analysis. Our results indicated no favorable change in serum triglyceride (n = 13, WMD = -0.06, 95% CI: -0.15, 0.03 mmol/L), total cholesterol (n = 15, WMD = 0.01, 95% CI: -0.14, 0.16 mmol/L), LDL-C (n = 10, WMD = -0.01, 95% CI: -0.17, 0.19 mmol/L), HDL-C (n = 10, WMD = 0.03, 95% CI: -0.001, 0.06 mmol/L), and CRP (n = 5, WMD = 0.82, 95% CI: -0.01, 1.64 mg/L) after PTX in PHPT patients. However, glucose (n = 24, WMD = -0.16, 95% CI: -0.26, -0.06 mmol/L), serum insulin (n = 12, WMD = -1.11, 95% CI: -1.73, -0.49 µIU/mL), systolic (n = 17, WMD = -10.14, 95% CI: -12.27, -8.01 mmHg), and diastolic (n = 16, WMD = -5.21, 95% CI: -7.0, -3.43 mmHg) blood pressures were decreased after PTX, whilst a significant increase was observed in BMI (n = 13, WMD = 0.35, 95% CI: 0.19, 0.51 kg/m²).

CONCLUSIONS

PTX could improve glycemic parameters and blood pressure, without any significant change in serum lipoproteins and CRP.

A detailed appraisal of renal manifestations in primary hyperparathyroidism from Indian PHPT registry: Before and after curative parathyroidectomy

BACKGROUND

Primary hyperparathyroidism (PHPT) is a systemic disorder characterized by hypercalcaemia and inappropriately elevated parathyroid hormone (PTH). Renal manifestations are one of the main presenting features both in symptomatic and asymptomatic PHPT patients.

OBJECTIVES

We aimed to compare demographic, clinical and biochemical parameters of PHPT patients with and without renal manifestations and also analysed the influence of curative parathyroidectomy on renal functions.

METHODS

We retrospectively analysed the data of PHPT patients from the last 25 years (1995- March 2019) and compared the demographic and clinical presentation and biochemical measurements between patients with and without renal manifestations and evaluated the changes in renal functions after 1 year of curative parathyroidectomy.

RESULTS

Of the total 544 PHPT patients, 299 (55%) including 91 out of 141 (65%) males had renal manifestations. Among renal manifestations, nephrolithiasis and nephrocalcinosis were found in 41.7% and 27.6% PHPT patients, respectively. PHPT patients with renal manifestations had significantly higher creatinine (109.7 vs 79.6 µmol/L; P < .0001) and lower eGFR level (78.8 vs 93.9 mL/min/1.73 m² ; P < .0001) compared to patients without renal manifestations. Parathyroidectomy resolved the clinical symptoms with biochemical cure in the patients from both the groups. Patients with renal manifestations showed improvement in creatinine and eGFR levels after 1 year of curative parathyroidectomy; however, patients without renal manifestations showed no change in creatinine and eGFR levels.

CONCLUSION

Young age and male gender are predictors of renal manifestations in PHPT. Curative parathyroidectomy improves renal functions in PHPT patients with renal manifestations compared to PHPT patients without renal manifestation.

Effects of preoperative calcium levels and parathyroidectomy on renal function in primary hyperparathyroidism: a retrospective study

AIM

TTo assess the effects of preoperative calcium levels and parathyroidectomy on estimated glomerular filtration rate (eGFR) in patients of primary hyperparathyroidism (PHPT) with mild renal dysfunction or normal renal function.

METHODS

This retrospective study enrolled 71 patients who underwent parathyroidectomy for PHPT in the General Surgery Department at Ondokuz Mayis University Hospital from 2010 to 2018. All patients were histopathologically diagnosed with parathyroid adenoma. Total serum calcium, serum creatinine, serum intact parathyroid hormone (PTH), and serum 25-hydroxyvitamin D3 (25(OH)D3) were measured before and 3-6 months after surgery. Patients were assigned to the low eGFR group (60-90 mL/min/1.73 m2) or normal eGFR group (≥90 mL/min/1.73 m2) and to the low calcium group (≤11.2 mg/dL) or high calcium group (>11.2 mg/dL).

RESULTS

In the low eGFR and high calcium group, there were significantly more patients with hypertension and older age. In the normal eGFR and high calcium group, eGFR was significantly reduced after surgery. Independent predictors of eGFR change after surgery were age, pre- parathyroidectomy calcium, and pre-parathyroidectomy eGFR.

CONCLUSIONS

After surgery, patients with low eGFR had preserved renal function, whereas those with normal eGFR had decreased renal function. Mild renal dysfunction in PHPT was associated with older age, hypertension, and high calcium levels.

Primary hyperparathyroidism and hypertension

Although untreated primary hyperparathyroidism is associated with increased cardiovascular mortality, controversy exists regarding the therapeutic effects of parathyroidectomy on cardiovascular health. This review will examine the evidence linking primary hyperparathyroidism (PHPT) and cardiovascular disease, specifically hypertension, and evaluate the available literature regarding the natural history of hypertension after successful parathyroidectomy.

Effect of Parathyroidectomy on Cardiovascular Risk Factors in Primary Hyperparathyroidism: A Randomized Clinical Trial

CONTEXT

It remains unclear whether risk of cardiovascular diseases is increased in patients with mild (<1.45 mmol/L) to moderate (≥1.45 to 1.60 mmol/L) primary hyperparathyroidism (PHPT).

OBJECTIVE

We aimed to determine the short-term effect of parathyroidectomy (PTX) on arterial stiffness, cholesterol levels, and blood pressure (BP).

DESIGN

This study was a clinical trial randomly allocating patients to either PTX or a control group (no surgery). Follow-up was performed 3 months after surgery in the PTX group and 3 months after baseline in the control group.

SETTING

University hospital.

PARTICIPANTS

We recruited 79 patients with PHPT; 69 participants completed the study.

MAIN OUTCOMES

Office and ambulatory 24-hour BP, pulse wave velocity (PWV), augmentation index, and fasting plasma cholesterol levels.

RESULTS

At baseline, participants had a median level of ionized calcium of 1.41 mmol/L (range, 1.33 to 1.60 mmol/L) and PTH of 10.4 pmol/L (4.5 to 30.4 pmol/L). Median age was 64 years (range, 18 to 81) and 72% were females. Following PTX, plasma total cholesterol levels decreased significantly compared with the controls (P = 0.04). Changes in PWV, augmentation index, and ambulatory 24-hour BP did not differ between groups, except for an increase in ambulatory diastolic BP following PTX. However, in patients with baseline levels of ionized calcium ≥1.45 mmol/L, PWV decreased significantly in response to PTX compared with the control group (P = 0.03).

CONCLUSION

PTX may decrease risk of cardiovascular diseases in PHPT by lowering total cholesterol levels, although ambulatory diastolic BP increases in response to surgery. Patients with moderate to severe hypercalcemia may benefit from PTX by a decrease in PWV.

Primary aldosteronism complicated by hyperparathyroidism: report of one case and literature review

Primary aldosteronism (PA) is a category of secondary hypertension induced by inhibition of the renin-angiotensin system due to increased aldosterone secretion. Aldosterone-producing adenoma (APA) is the most common hypotype of PA. Primary hyperparathyroidism (PHPT) refers to the symptoms of increased bone resorption and increased calcium reabsorption of kidney tubules caused by parathyroid secretion and excessive synthesis of parathyroid hormone. APA, complicated with PHPT has been extremely rare in clinical practice. In this study, the diagnosis and treatment of one case of APA complicated by PHPT was reported. Relevant literature review was performed.

Factors associated with glomerular filtration rate variation in primary hyperparathyroidism after parathyroidectomy

Background/aim

Prolonged hypercalcemia impairs renal function, and a reduced glomerular filtration rate (GFR) is typical in advanced primary hyperparathyroidism (PHPT). There are scarce data related to predictors of renal impairment in patients with PHPT. Hence, we aimed to evaluate changes in kidney function in PHPT patients after parathyroidectomy (PTX) and identify factors associated with GFR variation in these patients.

Materials and methods

One hundred and twenty-five patients with PHPT who underwent surgery between 2012 and 2014 were enrolled in the study. Patients were divided into two groups according to GFR values: patients whose GFR was lower than 60 mL/min/1.73 m2 and higher than 60 mL/min/1.73 m2. Demographic and laboratory parameters were compared before and 6 months after parathyroidectomy.

Results

Prevalence of antihypertensive drug users and patients with renal cysts and parathormone (PTH) and alkaline phosphatase levels were higher in patients with GFR of ≥60 than in GFR of <60 mL/min/1.73 m2 (P < 0.05). Systolic BP, uric acid, and magnesium were decreased in patients with GFR of ≥60, but GFR did not change in the two groups after parathyroidectomy. After parathyroidectomy, calcium and PTH decreased but 25(OH)D3 and phosphorus increased in the two groups. In multiple regression analysis, age, calcium, and baseline GFR were independent predictors of GFR variation. Parathyroid adenoma volume and urinary calcium were not independent predictors of GFR change.

Conclusion

Older age, higher preoperative calcium, and GFR were factors associated with GFR increase in PHPT patients after parathyroidectomy. Further renal impairment was prevented by parathyroidectomy in PHPT patients.

The effect of surgery on fat mass, lipid and glucose metabolism in mild primary hyperparathyroidism

CONTEXT

Mild primary hyperparathyroidism has been associated with increased body fat mass and unfavorable cardiovascular risk factors.

OBJECTIVE

To assess the effect of parathyroidectomy on fat mass, glucose and lipid metabolism.

DESIGN, PATIENTS, INTERVENTIONS, MAIN OUTCOME MEASURES

119 patients previously randomized to observation (OBS; n = 58) or parathyroidectomy (PTX; n = 61) within the Scandinavian Investigation of Primary Hyperparathyroidism (SIPH) trial, an open randomized multicenter study, were included. Main outcome measures for this study were the differences in fat mass, markers for lipid and glucose metabolism between OBS and PTX 5 years after randomization.

RESULTS

In the OBS group, total cholesterol (Total-C) decreased from mean 5.9 (±1.1) to 5.6 (±1.0) mmol/L (P = 0.037) and LDL cholesterol (LDL-C) decreased from 3.7 (±1.0) to 3.3 (±0.9) mmol/L (P = 0.010). In the PTX group, the Total-C and LDL-C remained unchanged resulting in a significant between-group difference over time (P = 0.013 and P = 0.026, respectively). This difference was driven by patients who started with lipid-lowering medication during the study period (OBS: 5; PTX: 1). There was an increase in trunk fat mass in the OBS group, but no between-group differences over time. Mean 25(OH) vitamin D increased in the PTX group (P < 0.001), but did not change in the OBS group. No difference in parameters of glucose metabolism was detected.

CONCLUSION

In mild PHPT, the measured metabolic and cardiovascular risk factors were not modified by PTX. Observation seems safe and cardiovascular risk reduction should not be regarded as a separate indication for parathyroidectomy based on the results from this study.

MECHANISMS IN ENDOCRINOLOGY: Kidney involvement in patients with primary hyperparathyroidism: an update on clinical and molecular aspects

Primary hyperparathyroidism (PHPT) is the third most common endocrine disease. Kidney is a target of both chronic elevated PTH and calcium in PHPT. The classic PHPT complications of symptomatic kidney stones and nephrocalcinosis have become rare and the PHPT current presentation is asymptomatic with uncertain and long-lasting progression. Nonetheless, the routine use of imaging and of biochemical determinations have revealed the frequent occurrence of asymptomatic kidney stones, hypercalciuria and reduced kidney function in asymptomatic PHPT patients. Though the pathogenesis is far from being elucidated, PHPT is associated with reduced renal function, in terms of estimated glomerular filtration rate, and related increased morbidity and mortality. In the last decade, the effort of the Kidney Disease: Improving Global Outcomes (KDIGO) panel of experts highlighted that even mild reduction of kidney function is associated with increased risk of cardiovascular disease. These considerations provided the basis for the Fourth Workshop recommendations of a more extensive diagnostic workout about kidney features and of wider criteria for parathyroid surgery including asymptomatic kidney disease. Moreover, kidney involvement in PHPT is likely to be affected by variants of genes coding the key molecules regulating the calcium and ions renal handling; these features might have clinical relevance and should be considered both during diagnostic workout and follow-up. Finally, the effects of parathyroid surgery and of medical treatment on kidney involvement of PHPT are reviewed.

Surgery or no surgery: What works best for the kidneys in primary hyperparathyroidism? A study in a multi-ethnic Asian population

INTRODUCTION

Whether parathyroidectomy is more beneficial to renal function when compared to medical therapy or observation in primary hyperparathyroidism (PHPT) is unclear. Neither has this premise been explored in non-Caucasian populations. The estimated glomerular filtration rate (eGFR) threshold below which parathyroid hormone (PTH) levels rise if at all in PHPT has also not been established. We determined if surgery was superior to medical therapy and observation in a multi-ethnic Asian patient population with PHPT and whether there was an eGFR threshold below which PTH levels further increased in them.

METHODS

Retrospective evaluation of patients with PHPT.

RESULTS

There were 68.6% Chinese, 17.4% Malays, 10.7% Indians, and 3.3% Eurasians. The median (interquartile range) follow-up was 18.0 months (4.5-46.8). At last follow-up, eGFR in the surgical (80 ± 30 ml/min) was higher than the medical (52 ± 32 ml/min) or observation groups (48 ± 33 ml/min); P < 0.01. This difference persisted after adjusting for age, gender, ethnicity, pre-intervention eGFR levels, nephrolithiasis, serum calcium, phosphate, urinary calcium, and duration of follow-up; P = 0.035. There was no definite eGFR level below which PTH values rose.

CONCLUSION

Our study provides compelling evidence that in PHPT, surgery may be associated with a better renal outcome compared to medical management or observation. This has to be confirmed through prospective randomized controlled trials and the reasons for this finding have to be elucidated through functional and histological measures. The finding in our study of a lack of a specific eGFR threshold below which PTH levels further rose challenges the concept of a fixed renal threshold for secondary elevations of PTH in PHPT.

Renal impairment as a surgical indication in primary hyperparathyroidism: do the data support this recommendation?

CONTENT

Management of primary hyperparathyroidism has evolved over the past two decades, yet impaired renal function has consistently been a surgical indication. This recommendation has been based upon the historical association between primary hyperparathyroidism and renal impairment, and a review of the literature is needed to determine whether such a recommendation is warranted.

EVIDENCE ACQUISITION AND SYNTHESIS

PubMed was utilized to identify English-language articles published between January 1990 and February 2014 using keywords related to hyperparathyroidism and renal function. The keywords were "primary hyperparathyroidism," "surgery," "parathyroidectomy," "kidney," "renal," "glomerular filtration rate," and "creatinine." Of the 1926 articles obtained with this search, all articles germane to the topic that quantified the relationship between primary hyperparathyroidism and renal function were included. All references within these articles were investigated for inclusion. When helpful, data tables were constructed to summarize the results succinctly.

CONCLUSIONS

A secondary elevation of PTH levels has not been consistently shown to occur at the threshold currently indicated for surgical intervention. While renal impairment is seen with more significant disease, mild asymptomatic primary hyperparathyroidism has not been conclusively associated with renal impairment. Furthermore, there is no evidence to suggest that surgically curing primary hyperparathyroidism via a parathyroidectomy has any impact upon renal function.

Unmasked renal impairment and prolonged hyperkalemia after unilateral adrenalectomy for primary aldosteronism coexisting with primary hyperparathyroidism: report of a case

We herein report the case of a patient with critical hyperkalemia after unilateral adrenalectomy (ADX) for aldosterone-producing adenomas, which were coexisting with primary hyperparathyroidism. A right adrenal tumor oversecreting mineral corticoid was identified in a 62-year-old female whose kidney function had been impaired due to primary hyperaldosteronism and hyperparathyroidism. The ADX improved her hypertension with normalization of the plasma aldosterone concentration, but without adequately increasing her plasma renin activity. Her eGFR further decreased postoperatively, hyperkalemia appeared and the serum potassium level rose to 6.3 mEq/L at 3 months after ADX. Then, treatment with calcium polystyrene sulfonate jelly was started. Eight months after ADX, a left lower parathyroidectomy was performed, and the serum calcium and intact parathyroid hormone levels decreased to the normal range. The hyperkalemia was difficult to control within 20 months postoperatively without treatment with calcium polystyrene sulfonate jelly or hydrocortisone. This suggests that unmasking the renal impairment and relative hypoaldosteronism after ADX might induce critical hyperkalemia.

Hyperparathyroidism

Hyperparathyroidism is due to increased activity of the parathyroid glands, either from an intrinsic abnormal change altering excretion of parathyroid hormone (primary or tertiary hyperparathyroidism) or from an extrinsic abnormal change affecting calcium homoeostasis stimulating production of parathyroid hormone (secondary hyperparathyroidism). Primary hyperparathyroidism is the third most common endocrine disorder, with the highest incidence in postmenopausal women. Asymptomatic disease is common, and severe disease with renal stones and metabolic bone disease arises less frequently now than it did 20-30 years ago. Primary hyperparathyroidism can be cured by surgical removal of an adenoma, increasingly by minimally invasive parathyroidectomy. Medical management of mild disease is possible with bisphosphonates, hormone replacement therapy, and calcimimetics. Vitamin D deficiency is a common cause of secondary hyperparathyroidism, particularly in elderly people. However, the biochemical definition of vitamin D deficiency and its treatment are subject to much debate. Secondary hyperparathyroidism as the result of chronic kidney disease is important in the genesis of renal bone disease, and several new treatments could help achieve the guidelines set out by the kidney disease outcomes quality initiative.

Cardiovascular aspects of primary hyperparathyroidism

Data concerning the cardiovascular manifestations of primary hyperparathyroidism (PHPT) are inconsistent, which is due, in part, to the decrease in disease severity over the last several decades. In areas where patients tend to be more symptomatic, data support the presence of cardiovascular findings including myocardial and vascular calcification as well as increased cardiovascular mortality. Data from the cohorts in whom the disease is characterized by mild hypercalcemia, suggest that clinically overt cardiovascular manifestations are unusual in PHPT. Recent data, however, support the presence of subtle cardiovascular manifestations in mild disease, such as changes in endothelial function as well as increased vascular stiffness and perhaps diastolic dysfunction. Left ventricular hypertrophy is a more consistent finding across a spectrum of disease severity, though this finding may be related to hypertension, which has long been associated with PHPT.

Reelevation of parathyroid hormone level after parathyroidectomy in patients with primary hyperparathyroidism: importance of decreased renal parathyroid hormone sensitivity

BACKGROUND

We hypothesized that impaired peripheral sensitivity to parathyroid hormone (PTH) may play a role in reelevation of PTH after successful operation for primary hyperparathyroidism (pHPT).

METHODS

Factors affecting reelevation of PTH were determined in 90 patients who underwent parathyroidectomy for pHPT. PTH/nephrogenous cyclic adenosine monophosphate ratio, as an index of renal resistance to PTH, was examined in relation to factors shown to influence reelevation of PTH.

RESULTS

Serum PTH levels were elevated above the upper limit of normal in 23 patients (26%) at 1 week and in 39 patients (43%) at 1 month after parathyroidectomy. These 39 normocalcemic patients with elevated serum PTH at 1 month after parathyroidectomy had a higher preoperative serum level of PTH and lower serum phosphate and 25-hydroxyvitamin D (25OHD) concentrations than those with normal PTH (n = 59). Elevated PTH and low 25OHD were shown by multivariate analysis to be significant predictors of reelevation of PTH. Renal resistance to PTH was higher in patients with vitamin D deficiency or renal insufficiency than in patients with normal serum vitamin D concentrations or normal renal function, and it increased according to increases in levels of PTH.

CONCLUSIONS

The mechanism of PTH reelevation in patients with pHPT after successful parathyroidectomy appears to be renal resistance to PTH.

The management of primary hyperparathyroidism

Recent improvements in parathyroid imaging have led to renewed interest in the criteria for, and the surgical approach to, parathyroidectomy. It therefore seemed appropriate to review current evidence relating to the evaluation and management of primary hyperparathyroidism for those working within a general endocrine service. The recommendations are based on an electronic search spanning the past decade using the search terms hyperparathyroidism, management and parathyroidectomy/surgery, but we have also included key publications outside this period. The findings have been graded systematically (Appendix), according to the quality of the information available, to indicate the level of evidence on which they are based.

Role of surgery in mild primary hyperparathyroidism in the elderly

BACKGROUND

The appropriate management of elderly patients with mild hyperparathyroidism is the subject of much debate.

METHODS

A Medline literature search was conducted using the keywords 'hyperparathyroidism', 'asymptomatic' and 'elderly'. The references of the primary sources were examined for further citations. Personally collected cullings from journals and abstracts from journals were used as an additional source of data.

RESULTS AND CONCLUSION

No prospective randomized controlled trial comparing parathyroidectomy with conservative management for patients with mild or asymptomatic hyperparathyroidism has been published. There are a number of longitudinal studies that attempt to characterize the natural history of hyperparathyroidism, but most do not stratify patients according to age when assessing outcome. None the less, it is clear that elderly patients present with a different spectrum of problems, particularly indistinct neuropsychiatric and musculoskeletal symptoms, and these are likely to be improved by surgery. The evidence allows the conclusion that the truly asymptomatic elderly patient can be successfully managed conservatively; there is a good prospect of benefit from surgery for those with symptomatic disease, and such patients should not be denied an operative option.

[End-stage renal failure following parathyroidectomy for advanced primary hyperparathyroidism]

PURPOSE

We report two cases of long-standing, advanced primary hyperparathyroidism with renal failure. After surgery the two patients presented with marked hypocalcemia and deterioration of renal function which required dialysis 2 and 3 months after parathyroidectomy. These two cases lead us to consider that renal function should be studied before and after surgery in patients operated on for primary hyperparathyroidism.

METHODS

In 19 patients operated on for hyperparathyroidism with few symptoms and without renal failure or with very moderate renal failure, blood creatinine and creatinine clearance were measured before (T1) and 1 year (T12) parathyroidectomy.

RESULTS

No significant overall changes in the following parameters were observed: blood creatinine T1 71 +/- 19 mumol/L, T12 82 +/- 20 mumol/L, CrCl T1 72 +/- 13 mL/min, CrCl T12 70 +/- 19 mL/min. However, in the patient with greatest deterioration of renal function, CrCl decreased from 45 mL/min at T0 to 33 mL/min at T12.

CONCLUSION

A review of the literature shows that in certain cases, renal insufficiency present before cervicotomy may worsen after surgery even if hypercalcemia is corrected. The mechanism is still unclear. A sharp decrease in parathormonemia and parathyroid hypertensive factor may play a role via intrarenal hemodynamic changes.

Metabolic abnormalities related to cardiovascular risk in primary hyperparathyroidism: effects of surgical treatment

OBJECTIVES

Untreated primary hyperarathyroidism (pHPT) is accompanied by an excessive morbidity in circulatory disorders, associated with blood pressure and diabetes. The aim of the present study was to further penetrate the impact of pHPT on glucose, urate, lipid and lipoprotein concentrations, known to be interrelated metabolic cardiovascular risk factors.

DESIGN

Longitudinal study of patients with pHPT before and 1 year after surgical treatment.

SETTING

Departments of Internal Medicine and Surgery, Lund University Hospital.

SUBJECTS

One hundred and seventeen consecutive patients with pHPT referred to surgical treatment. At presentation. 11 patients had previously diagnosed diabetes mellitus.

INTERVENTION

All patients were successfully operated for pHPT.

MAIN OUTCOME MEASURES

Fasting blood glucose and serum concentrations of cholesterol, triglyceride and urate were determined before and 1 year after surgery. The concentration of LDL- and HDL-cholesterol was separately analyzed in 21 cases. These data as well as the systolic and diastolic blood pressure were related to intact PTH and ionized calcium at presentation. Glomerular filtration was separately measured pre-operatively and related to the urate values.

RESULTS

While the mean value for glucose remained unchanged among 11 patients with previously diagnosed diabetes at presentation, a significant decrease of glucose from 5.03+/-0.13 to 4.71+/-0.08 mmol/L (P < 0.05) was found among patients without known diabetes. Out of these patients, eight had diabetic glucose values at presentation, decreasing from 8.35+/-0.54 to 5.10+/-0.35 mmol/L (P < 0.05), and 12 had glucose values indicating impaired glucose tolerance, decreasing from 5.94+/-0.06 to 5.10 +/-0.38 mmol/L (P < 0.05) after surgery. Total cholesterol and trigylceride concentrations were not changed. However, male patients had significantly lower triglyceride levels at follow-up, 1.16+/-0.09 mmol/L compared to 1.57+/-0.14 mmol/L before surgery (P < 0.05). Significantly lower triglyceride values were also found among patients with glucose values indicating impaired glucose tolerance at presentation. The LDL/HDL cholesterol ratio remained normal. The serum level of urate decreased in both male and female patients after surgery, and was positively correlated to the PTH and ionized calcium values and inversely correlated to renal function before treatment. There was no significant correlation between calcium or PTH and the other metabolic variables studied.

Regulation of blood pressure with calcium-dependent dopamine synthesizing system in the brain and its related phenomena

The effects of calcium on blood pressure regulation remain controversial. Although the mechanism by which calcium increases blood pressure when it is given intravenously and acutely has been elucidated, that by which calcium reduces blood pressure when it is supplemented chronically and slightly through daily diet is unclear. From a number of animal experiments concerning the effects of calcium on blood pressure, we believe that calcium ions have two separate roles in the regulation of blood pressure through both central and peripheral systems: (1) calcium ions reduce blood pressure through a central, calcium/calmodulin-dependent dopamine-synthesizing system and (2) calcium ions increase blood pressure through an intracellular, calcium-dependent mechanism in the peripheral vasculature. These concepts were applied to elucidate the mechanisms underlying hypertension in spontaneously hypertensive rats (SHR) and changes in blood pressure in other experimental animals, and the following conclusions were reached. The decrease of the serum calcium level in spontaneously hypertensive rats (SHR) causes a decrease in calcium/calmodulin-dependent dopamine synthesis in the brain. The subsequent low level of brain dopamine induces hypertension. The increase in susceptibility to epileptic convulsions and the occurrence of hypertension in epileptic mice (El mice) may be linked through a lowering of calcium-dependent dopamine synthesis in the brain, and epilepsy and hypertension may be associated. Exercise leads to increases in calcium-dependent dopamine synthesis in the brain, and the increased dopamine levels induce physiological changes, including a decrease in blood pressure. Cadmium which is not distinguished from calcium by calmodulin, activates calmodulin-dependent functions in the brain, and increased dopamine levels may decrease blood pressure. In this report, our studies are considered in light of reports from many other laboratories.

Secondary hypertension: evaluation and treatment

Most patients with hypertension in the United States have essential (primary) hypertension (95%), the cause of which is unknown. The remaining 5% of adults with hypertension have the secondary form of hypertension, the cause and pathophysiologic process of which are known. Internists and other primary care physicians refer to this as treatable or curable hypertension, because the hypertension can be managed or even controlled with medications. Similarly, the condition is called surgical hypertension by surgeons in the belief that once the cause is determined and identified, surgical intervention will result in cure of hypertension. Secondary causes of hypertension include renal parenchymal disease, renovascular diseases, coarctation of the aorta, Cushing's syndrome, primary hyperaldosteronism, pheochromocytoma, hyperthyroidism, and hyperparathyroidism. Occasionally included in this category are alcohol- and oral contraceptive-induced hypertension and hypothyroidism, but these conditions are not discussed herein. The evaluation of secondary hypertension is of interest and can bring together different facets of anatomy, physiology, pharmacology, and radiology in the medical and surgical treatment of these disorders. Despite enthusiasm that can be generated in the evaluation of these conditions, evaluation can be expensive and should not be conducted for all patients with hypertension. Features that aid in the diagnosis of secondary hypertension include the following: 1. Onset of hypertension before the age of 20 or after the age of 50 years. The presence of hypertension at a young age may suggest coarctation of the aorta, fibromuscular dysplasia, or an endocrine disorder. Hypertension found for the first time after the age of 50 years may suggest the presence of renovascular hypertension caused by atherosclerosis. 2. Markedly elevated blood pressure or hypertension with severe end-organ damage, as in grade III or IV retinopathy. These findings suggest the presence of renovascular hypertension or pheochromocytoma. 3. Specific body habitus and ancillary physical findings. For example, truncal obesity and purple striae occur with hypercortisolism, and exophthalmos is associated with hyperthyroidism. 4. Resistant or refractory hypertension (poor response to medical therapy usually necessitating use of more than three antihypertensive medications from three different classes). 5. Specific biochemical test that suggest the existence of certain disorders, such as hypercalcemia in hyperparathyroidism, hyperglycemia in Cushing's syndrome and pheochromocytoma, and unprovoked hypokalemia with renin-producing tumors, primary hyperaldosteronism, or renin-mediated renovascular hypertension. 6. Other characteristics that may suggest secondary hypertension such as abdominal diastolic bruits (renovascular hypertension), decreased femoral pulses (coarctation of the aorta), or bitemporal hemianopias (Cushing's disease). A combination of a good history and physical examination, astute observation, and accurate interpretation of available data usually are helpful in the diagnosis of a specific causation.

Pre-operative evaluation of risk factors for complications in patients with primary hyperparathyroidism

Impairments in cardiovascular, respiratory and kidney function are considered as risk factors for complications following surgery. As the indication for surgery in asymptomatic primary hyperparathyroidism (HPT) is controversial, 123 patients undergoing surgery for HPT and 104 control subjects scheduled for common surgical procedures were evaluated pre-operatively. Compared with the age- and sex-matched control group, serum calcium (P < 0.001), creatinine (P < 0.01) and glucose (P < 0.02) were all increased in the HPT group, while peak expiratory flow (PEF) was decreased (P < 0.04). Furthermore, the patients with HPT, compared with controls, were more often receiving antihypertensive medication (P < 0.005) and were more likely to have a history of congestive heart disease (P < 0.01), thromboembolic diseases (P = 0.05), stroke (P = 0.06) or diabetes mellitus (P < 0.02). Increased frequencies of ST-segment depression (P < 0.001) and T-wave abnormalities (P = 0.05) at electrocardiography together with an increased prevalence of heart enlargement visible at chest radiography (P < 0.01) were also seen in the HPT group when compared with the controls. All HPT patients and controls survived, but one HPT patient suffered a myocardial infarction in the post-operative period. In conclusion, the present study showed the pre-operative risk factor profile to be altered in HPT subjects with impairments in both cardiovascular and respiratory functions as well as in kidney function and glucose control. These findings should be kept in mind when the indications for surgery in asymptomatic patients with HPT are discussed.

Parathyroid hormone in blood pressure and volume homeostasis in healthy subjects, hyperparathyroidism, liver cirrhosis and glomerulonephritis. A possible interaction with angiotensin II and atrial natriuretic peptide

In order to elucidate a participation of intact parathyroid hormone (PTH(1-84)) in blood pressure (BP) and body fluid homeostasis, we studied fluctuations of PTH(1-84) during manipulations of BP in hyperparathyroid and healthy subjects, and during manipulations of blood volume in patients with glomerulonephritis or liver cirrhosis and in controls. Angiotensin II induced BP elevation was associated with increased values of PTH(1-84) both in healthy subjects (12-25 ng l-1, medians, p < 0.01), in patients with primary hyperparathyroidism (94-125 ng l-1, p < 0.01), in patients with low calcium due to end stage renal disease before requirement of dialysis (95-151 ng l-1, p < 0.02), and in patients with tertiary hyperparathyroidism (221-264 ng l-1, p < 0.05), but not in dialysis patients without hypercalcaemia (126-174 ng l-1, NS). The changes could not be attributed to reduction of serum calcium, but probably to the increase of plasma angiotensin II, which was positively correlated to the increase of serum PTH(1-84) in the healthy subjects (p = 0.619, n = 15, p < 0.05) and in the patients with primary hyperparathyroidism (p = 0.549, n = 18, p < 0.05). Noradrenaline induced BP elevation did not have a similar effect on PTH(1-84), and changes of PTH(1-84) were not related to changes of BP. Volume depletion after furosemide injection, also accompanied by increased levels of angiotensin II, resulted in elevation of PTH(1-84) in controls, cirrhotics, patients with glomerulonephritis without the nephrotic syndrome, but not in nephrotic patients. Volume depletion induced by bolus injection of atrial natriuretic peptide (ANP) was associated with decreased PTH(1-84) in healthy subjects (20-18 ng l-1, p < 0.02), but not in patients with nephrotic syndrome and liver cirrhosis. Volume expansion induced by albumin infusion caused increased plasma levels of ANP, but PTH(1-84) was unaltered. Thus, angiotensin II may be able to stimulate, and ANP to inhibit release of PTH(1-84), and PTH(1-84) may be involved in the regulation of BP and body fluid homeostasis. BP changes or changes in blood volume per se do not seem to influence PTH(1-84) levels.

PHF: the new parathyroid hypertensive factor

Parathyroid Hypertensive Factor (PHF) was discovered in SHR rats as a circulating substance with a unique delayed (60-90 min) hypertensive effect when injected into a normotensive assay rat. Subsequently, this correlation with hypertension was established in humans, especially in low-renin, salt-sensitive patients. Animal model studies also confirmed this correlation. Endocrinectomy and glandular replacement studies suggested that the parathyroid gland was the source of PHF. Subsequently, glands and cells in culture were also shown to secrete the substance. Other studies verified the parathyroid origin of PHF. The mechanism of action of PHF was shown to rely mainly on the opening of L-type calcium channels in vascular smooth muscle cells with an increase in [Ca2++]i. It is known that diseases other than hypertension often show increased [Ca2++]i and clinical features similar to hypertension, among them Type II diabetes. A recent study shows a correlation between circulating PHF level and Type II diabetes irrespective of the blood pressure status of the patient. It is suggested that PHF may be a [Ca++]i modulator, an excessive amount of which in the circulation may act on various target tissues, resulting in various disease symptoms with hypertension as an example. There may be many other such PHF-related diseases yet to be identified.

Parathyroid hormone/adenylate cyclase coupling in vascular smooth muscle cells

Parathyroid hormone (PTH) has been implicated in hypertension, but PTH infusion results in vasodilation. PTH activates adenylate cyclase in vascular smooth muscle, but little is known about the factors that regulate PTH receptor/adenylate cyclase coupling in vascular cells. To characterize hormone-receptor signaling, we measured cyclic AMP levels in rat arterial smooth muscle cells in culture exposed to PTH (bovine 1-34). PTH yielded time- and concentration-dependent increases in cyclic AMP levels. Compared with isoproterenol, PTH was more potent, with a threshold at 2 x 10(-9) versus 5 x 10(-8) mol/L and half maximal responses at 10(-8) versus 2.4 x 10(-7) mol/L. PTH-induced increases in cyclic AMP were independent of extracellular calcium, cyclooxygenase metabolites, phospholipase C, and protein kinase C because PTH-induced increases in cyclic AMP were not prevented by variations in extracellular calcium, indomethacin, angiotensin II, vasopressin, and protein kinase C activators or inhibitors. PTH/adenylate cyclase coupling was G protein-dependent because increases in cyclic AMP were prevented by preincubation with cholera toxin but not with pertussis toxin. Prolonged exposure to PTH resulted in time- and concentration-dependent homologous desensitization of cyclic AMP responses. Desensitization occurred proximal to G protein/adenylate cyclase because after prolonged PTH, responses to forskolin and cholera toxin remained intact. Desensitization was independent of protein kinase A and receptor sequestration because cyclic AMP responses remained after prolonged exposure to forskolin and pretreatment with phenylarsine oxide, colchicine, and cytochalasin D. We conclude that in vascular smooth muscle cells, PTH is coupled to adenylate cyclase through a cholera toxin-sensitive G protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Unchanged noradrenaline reactivity and blood pressure after corrective surgery in primary hyperparathyroidism

In order to evaluate the role of the hyperparathyroid state for blood pressure and volume homeostasis, eight patients with primary hyperparathyroidism were studied before and after corrective surgery. Neither noradrenaline induced blood pressure changes nor basal blood pressure were affected by the operation, and the values were the same as in an age- and sex-matched control group. Noradrenaline infusion induced an increase in PTH(1-84) values before (72-86 ng l-1, medians, p < 0.02), in contrast to a decrease after (28 to 19 ng l-1, p < 0.05) operation for primary hyperparathyroidism. Basal plasma atrial natriuretic peptide was lower before than after removal of adenomata (3.2 vs. 4.8 pmol l-1, medians, p < 0.02). Cyclic 3'-5'-guanosine monophosphate was not significantly changed (4.7 vs. 5.5 nmol l-1). Aldosterone was higher before than after surgery (139 vs. 71 pmol l-1, p < 0.02), whereas angiotensin II was unaltered (20 vs. 9 pmol l-1). Arginine vasopressin was higher before than after the operation (0.9 vs. 0.7 pmol l-1, p < 0.05), but urinary excretion of prostaglandin E2 was unchanged. In conclusion primary hyperparathyroidism was not associated with changes in noradrenaline reactivity or basal blood pressure despite derangements of hormones adjusting sodium and water homeostasis. It is suggested that the hormonal changes may be secondary to a relative volume depletion.

Expression of parathyroid hypertensive factor in hypertensive primary hyperparathyroid patients

Hypertension is frequently associated with primary hyperparathyroidism, yet the mechanism of such hypertension is unknown. Parathyroid hypertensive factor (PHF) is a circulating hypertensive factor found in a proportion of human essential hypertensive patients as well as in spontaneously hypertensive rats (SHR). In the latter case, PHF has been shown to be secreted by the parathyroid gland. The purpose of this study was to determine if PHF expression might be responsible for the hypertension seen in primary hyperparathyroidism. Ten hypertensive and 10 normotensive primary hyperparathyroid patients underwent measurement of blood pressure and PHF pre- and post-parathyroidectomy. Cases reported are those of parathyroid adenomas. There were no significant differences between the hypertensive and normotensive groups preoperatively except that 9 out of 10 of the hypertensive group had significant PHF levels (mean 11 +/- 2 mm Hg vs 0.6 +/- 2 mm Hg, respectively, p = 0.003). Post-operative change in mean arterial pressure could be predicted by pre-operative PHF level, with all PHF-positive patients showing a fall in blood pressure (r = -0.73, p < 0.01). Post-operatively, PHF was undetectable in PHF-positive patients. These results suggest that the parathyroid gland can express PHF in humans and that such expression may be responsible for a proportion of the high reported incidence of hypertension in primary hyperparathyroidism.

Long-term effects of parathyroidectomy for primary hyperparathyroidism on arterial hypertension

The prevalence of arterial hypertension in primary hyperparathyroidism (PHPT) is higher than in the general population. With the aim of determining the evolution of hypertension associated with PHPT, we analyzed a group of 56 patients followed for a mean of 60 months (range 10-101 months) after successful parathyroidectomy for PHPT. The study group consisted of 16 men and 40 women. The mean age was 49 +/- 12 years (range 18-73 years). None of the patients had renal impairment. Two hypertensive patients died during the follow-up from complications related to their hypertension. Twelve (21.8%) patients were hypertensive before parathyroid surgery (systolic greater than 160 mmHg and/or diastolic greater than 90 mmHg). Pre-operative midregion serum parathyroid hormone concentration was higher in the hypertensive patients than in normotensive patients (2.7 +/- 2.4 vs 0.82 +/- 0.4 mu iEq/l, p = 0.018). Pre-operative creatinine clearance was lower in the hypertensive patients than in normotensive patients (65.4 +/- 27.5 vs 86.7 +/- 26 ml/min, p = 0.002). There were no significant differences between normotensive and hypertensive patients in age, sex, body weight, clinical manifestations, weight of parathyroid tissue removed, and calcium metabolism, or in plasma concentrations of magnesium, uric acid, cholesterol, proteins, or albumin. During follow-up, none of the patients with pre-operative hypertension became normotensive, whereas 32% of the patients who were normotensive preoperatively developed clinical hypertension. The global prevalence of postoperative hypertension was thus 48%. The patients that developed hypertension after parathyroidectomy were followed for a longer period than the normotensive patients (76 +/- 17 vs 53 +/- 10 months, p = 0.005), had a lower postoperative creatinine clearance (74 +/- 28 vs 90 +/- 25 mg/min, p = 0.07), and higher cholesterol levels (6.2 +/- 1.5 vs 5.5 +/- 0.9 mmol/L, p = 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma ionized calcium and cardiovascular risk factors in mild primary hyperparathyroidism: effects of long-term treatment with active vitamin D (alphacalcidol)

Primary hyperparathyroidism (HPT) has been associated with hypertension, hyperinsulinaemia, hypertriglyceridaemia and hyperuricaemia. In the present study, plasma ionized calcium (Ca2+) was studied in relation to cardiovascular risk factors in 20 subjects with mild hypertension. Plasma Ca2+ was found to be negatively correlated with fasting serum insulin, triglycerides and urate, and with diastolic blood pressure (DBP). However, after the interaction of the different risk factors had been taken into account in the multiple regression analysis, only the relationship between Ca2+ and serum insulin was significant (r = 0.55, P less than 0.01). In a previous double-blind, placebo-controlled study 1 micrograms alphacalcidol, a synthetic analogue of 1,25 dihydroxy-vitamin D3, induced a decrease in blood pressure in mild HPT subjects. In the present study, the highest dose that did not further aggravate the hypercalcaemia was given in a long-term study over a 12-month period to 18 mild HPT subjects (average dose, 1.75 micrograms daily). The treatment induced a reduction in body weight of 0.9 kg (P less than 0.05) and an increase in serum urate from 330 +/- 92 to 380 +/- 104 mmol l-1 (P less than 0.01). A reduction in blood pressure was only observed at the end of the study, from 142 +/- 17/86.6 +/- 9.1 to 139 +/- 13/82.9 +/- 8.9 mmHg (P less than 0.05 for DBP). The reduction in systolic blood pressure was significantly correlated with the reduction in body weight induced by treatment (r = 0.63, P less than 0.02). No consistent changes in glucose or lipid metabolism were induced by treatment.

Asymptomatic primary hyperparathyroidism

The criteria used in selecting patients with asymptomatic hyperparathyroidism (HPT) for surgery remain controversial. Do patients with asymptomatic HPT have less severe disease (smaller glands and less derangement of biochemistry) than those with symptoms? We studied a consecutive series of 111 patients with HPT surgically treated and compared the symptomatic patients (n = 83) and asymptomatic patients (n = 28). There were no significant differences between the two patient groups with respect to age, serum calcium, PTH (intact 1-84), and excised gland weights (adenomas). Hypercalcemia was cured in all patients. The natural history of mild or asymptomatic HPT is unknown, but we summarize the current knowledge relating to mortality, cardiovascular/renal disease, psychiatric and neuromuscular disorders, and bone disease. Symptoms of HPT do not correlate with the degree of biochemical and pathological derangement. Furthermore clinical assessment does not predict severity of disease and should not be the sole basis of selection for surgery. The results of surgery for primary HPT permit us to advocate a liberal approach to the selection of asymptomatic patients for operation.

Cardiovascular risk factors in primary hyperparathyroidism: a 15-year follow-up of operated and unoperated cases

The need for treatment of mild and apparently asymptomatic primary hyperparathyroidism (HPT) is questioned, but a raised incidence of cardiovascular disease has been regarded as evidence in favour of surgery. While it is well known that several risk factors for cardiovascular disease (hypertension, hyperlipidaemia and diabetes mellitus/impaired glucose tolerance) are overrepresented in HPT, it is not known whether surgery provides long-term normalization in these respects and reduces the risk of premature death. In a 15-year follow-up of a cohort of 172 subjects in whom mild hypercalcaemia was initially detected during a health screening, it was found that 56 subjects had died. 17 individuals had been operated on for HPT, 47 individuals were persistently hypercalcaemic, while 45 subjects had serum calcium within the normal range (seven individuals were lost to follow-up). There had been no significant differences in blood pressure between these groups of mildly hypercalcaemic patients and age- and sex-matched controls at the initial screening, but at follow-up blood pressure was significantly higher not only in subjects with persistent hypercalcaemia, but also in those who had been successfully operated on for HPT. Neither of the hypercalcaemic groups showed any significant deviations from the controls with regard to indices of lipid or glucose metabolism. These findings suggest that there is no simple cause-and-effect relationship to account for the propensity toward high blood pressure in primary HPT. Consequently it cannot be assumed that surgery for HPT will eliminate the increased risk of cardiovascular disease in patients with mild HPT.

Influence of transplantation of parathyroid glands on blood pressure development in stroke prone spontaneously hypertensive rats and in normotensive Wistar Kyoto rats

The influence of the parathyroid glands (PTG) on the development of high blood pressure (BP) in stroke prone spontaneously hypertensive (SHR/SP) and Wistar Kyoto (WKY) rats has been studied. After ablation of their own PTG's SHR/SP received PTG's from WKY rats and vice versa. After transplantation (TRPL) a normal calcium and parathyroid hormone (PTH) status was preserved during the whole observation period. One group of animals received a high salt diet (8% NaCl) for 4 weeks after transplantation, the other group received a normal rat chow for 3 months. In SHR/SP, which had PTG-transplants from WKY rats, the development of BP was clearly attenuated compared to sham operated rats in both experimental groups. WKY rats with PTG's from SHR/SP became hypertensive after two weeks during salt loading and after six weeks under normal diet. Sham operated WKY rats remained normotensive. The results demonstrate that the parathyroid gland is involved in the pathogenesis of hypertension, but the only known secretory product of PTG's parathyroid hormone, seems not to be responsible for these effects.

Pre- and postoperative evaluation of renal function with five different tests in patients with primary hyperparathyroidism

Renal function was investigated immediately before and 1 year following parathyroidectomy in 19 patients with moderate hypercalcaemia. On both occasions, all patients underwent five different tests of glomerular and tubular function: plasma creatinine, creatinine clearance, 51Cr-EDTA-clearance, beta 2-microglobulin excretion and the desmopressin test. Glomerular filtration rate, as assessed by plasma creatinine and clearance of both creatinine and 51Cr-EDTA, was normal in most patients, and was little affected by restoration of normocalcaemia. Renal concentrating capacity, as determined by the desmopressin test, was abnormally low in 14 of 19 patients, but increased significantly after surgery. It is concluded that serious renal damage is seldom encountered in present-day HPT patients, but that a treatable decrease in renal concentrating capacity often exists.

Hyperparathyroidism and abnormal calcitriol metabolism in the spontaneously hypertensive rat

Abnormalities of calcium metabolism and of its two principal regulating hormones, parathyroid hormone and 1,25-dihydroxyvitamin D3 (calcitriol), have been reported in the spontaneously hypertensive rat (SHR). Reports of abnormal calcitriol metabolism in the SHR by several groups have not provided measurements of tissue calcitriol receptors. Similarly, few data are available as to the parathyroid status of the SHR. In the present study, circulating calcitriol levels and intestinal and parathyroid gland calcitriol receptor status were determined in male SHR and in Wistar-Kyoto (WKY) rats. Parathyroid status was investigated by determination of parathyroid gland mass together with tissue micromorphometry and by quantitative histology of bone as a measure of the biological action of parathyroid hormone. Circulating calcitriol levels were reduced in the 11-week-old SHR compared with the WKY rat (165 +/- 23 vs. 194 +/- 28 pmol/l, p less than 0.01, mean +/- SD). Calcitriol-free ratio was diminished and maximal specific binding capacity for calcitriol was increased in the SHR in parathyroid tissue (172 +/- 4.9 vs. 123 +/- 6.6 fmol/mg protein, p less than 0.01) and in intestinal mucosa with no change of receptor affinity. Plasma ionized calcium (1.29 +/- 0.05 vs. 1.45 +/- 0.35 mmol/l, p less than 0.05) and phosphate (1.5 +/- 0.26 vs. 2.4 +/- 0.03 mmol/l, p less than 0.05) were significantly lower in the SHR. Parathyroid gland mass was increased in the SHR (59 +/- 12 vs. 17 +/- 7 micrograms/100 g body wt, p less than 0.001) as a result of hyperplasia and not hypertrophy. Higher osteoclast numbers were observed in SHR bone (27.6 +/- 0.79 vs. 23.9 +/- 0.66 osteoclasts/mm2, p less than 0.01), suggesting increased parathyroid hormone activity. In summary, in the 11-week-old SHR we observed reduced circulating calcitriol levels together with increased tissue calcitriol receptor numbers, increased parathyroid gland mass, and histological evidence of hyperparathyroidism. It is possible that these abnormalities influence the development of hypertension in the SHR.

Calcium metabolism and hypertension

Returning to the patient presented today, perhaps we can now understand some of his findings. As I noted, men are more likely to demonstrate alterations in calcium metabolism associated with elevations in blood pressure. Furthermore, blacks are more likely than whites to develop hyperparathyroidism, particularly in the third and fourth decades of life. It is unlikely, however, that parathyroid hormone was responsible for the increase in this patient's arterial pressure because PTH has a vasodilating action. Moreover, the long-term response to parathyroidectomy is more likely to be an increase rather than a decrease in blood pressure. It is also unlikely that the mild elevations in the serum total calcium observed in this patient were responsible for his hypertension. Correction of hypercalcemia by surgical intervention failed to improve the blood pressure. There is little evidence that mild, protracted hypercalcemia can account for increases in arterial pressure. Finally, the patient's alcohol abuse might have contributed to his elevated blood pressure; it is possible that his hypertension was in part a reflection of the abnormal calcium metabolism he developed as a consequence of the alcohol abuse. Answers to some questions we faced when we first studied this patient more than a decade ago can be provided by the wealth of basic research and clinical investigation that has occurred since. We now know that calcium metabolism is a factor in blood pressure regulation in some humans and in some experimental models. Epidemiologic studies document a consistent association between lower dietary calcium intake and higher blood pressures in humans. An additional non-pharmacologic approach has been identified that can produce a modest but important lowering of blood pressure in a subset of hypertensive individuals. Much data show that calcium-regulating hormones have important cardiovascular actions that might account for some of the mechanisms by which increased dietary calcium lowers blood pressure. Research in this area also has set the stage for exploring another theoretical mechanism for sodium-chloride-sensitive hypertension. Finally, a theoretical mechanism(s) has emerged that could provide a pathophysiologic link between hypertension and certain high-risk populations such as blacks, the elderly, type-II diabetics, and pregnant women. The principal clinical implication derived from this work to date is the following: In patients with mild to moderate hypertension, the level of dietary calcium intake should be assessed. Patients whose intake is deficient should be encouraged simply to maintain calcium intake at 800 to 1000 mg/day.(ABSTRACT TRUNCATED AT 400 WORDS)

Raised plasma intact parathyroid hormone concentrations in young people with mildly raised blood pressure

To study the role of parathyroid gland activity in early primary hypertension plasma concentrations of intact parathyroid hormone were measured in 90 untreated young subjects, aged 16-29, with stable midly raised blood pressure and in 40 normotensive control subjects selected from the same population in Zoetermeer, The Netherlands. Intact parathyroid hormone concentration was significantly higher in the hypertensive than the normotensive group (2.34 (SE 0.11) pmol/l v 1.47 (0.13) pmol/l, respectively; difference 0.87 pmol/l; 95% confidence interval 0.55 to 1.21; p less than 0.0001). Serum total calcium concentration was 2.36 (0.01) mmol/l in the hypertensive group and 2.42 (0.01) mmol/l in the normotensive group (difference 0.06 mmol/l; 95% confidence interval 0.02 to 0.09; p = 0.02). Urinary calcium excretion over 24 hours did not differ significantly between the two groups (4.17 (0.28) mmol/24 h in the hypertensive group and 3.89 (0.39) mmol/24 h in the normotensive group; difference 0.28 mmol/24 h; 95% confidence interval -0.66 to 1.22). In the hypertensive group both systolic and diastolic blood pressures increased slightly though significantly with intact parathyroid hormone concentrations. No obvious associations between serum calcium concentration and blood pressure were observed. These findings support the view that enhanced activity of the parathyroid gland may play a part in the early stage of primary hypertension.

Development of hypertension after correction of primary hyperparathyroidism

A statistical association between hypertension and hyperparathyroidism has been repeatedly reported, but the underlying pathogenetic mechanism has not been elucidated. A 51-year-old woman was hospitalized because of increasing motor disability caused by multiple bone and muscle aches with generalized weakness. She was found to have marked hypercalcemia and hypophosphatemia, increased parathyroid hormone secretion, but normal renal function and blood pressure level. After the identification and removal of a single parathyroid adenoma, the calcium/phosphate metabolism normalized in a relatively short time during which, however, hypertension developed in the absence of any other endocrine or renal dysfunction. A positive, highly significant relationship was observed between the progressive rise in blood pressure and the gradual increase in serum phosphate concentration occurring after the operation, suggesting that, in the hyperparathyroid phase, an underlying trend to hypertension could have been masked by the phosphate depletion, probably through its effects on cardiac and vascular smooth muscle function.

Adrenal responses to subtotal parathyroidectomy for primary hyperparathyroidism

Although it is well known that hypertension is often associated with primary hyperparathyroidism and that parathyroidectomy reverses or reduces this abnormality, the etiology of elevated blood pressure in hyperparathyroidism is still conjectural. We have analyzed serum calcium, blood pressure, and metabolites of adrenal cortical hormones before and after surgical therapy for hyperparathyroidism in 10 normotensive and six hypertensive patients with primary hyperparathyroidism. Successful parathyroidectomy lowered serum calcium (P less than 0.01) and diastolic blood pressure (P less than 0.05) in all subjects. Mean urinary aldosterone and Porter-Silber chromagens were within normal limits preoperatively in normotensive as well as hypertensive subjects. After parathyroidectomy, aldosterone levels as well as Porter-Silber chromagens decreased significantly in all patients (P less than 0.01). However, when normotensive and hypertensive subjects were analyzed separately, the decrease in aldosterone levels was significant only in the normotensive group (P less than 0.05) whereas the decrease in Porter-Silber chromagens reached significancy only in the hypertensive group (P less than 0.01). The results indicate that surgical therapy for hyperparathyroidism lowers serum calcium and blood pressure and is associated with a decrease in the excretion of adrenal steroid metabolites. It is suggested that the temporal relationship which exists between ionized calcium and steroidogenesis in hyperparathyroid patients contributes at least in part to the generalized decrease in blood pressure observed after successful parathyroidectomy.

The calcium paradox of essential hypertension

Three disparate observations--that calcium mediates vascular smooth muscle contraction, that calcium channel blockers lower blood pressure, and that increased dietary calcium intake can also ameliorate hypertension--constitute somewhat of a paradox. The complex interrelationships between calcium metabolism and essential hypertension are discussed in this review. Recent evidence suggests possible defects in intracellular calcium transport or in calcium binding in essential hypertension. This evidence, and the paradoxical therapeutic efficacy of both calcium channel blockers and supplemental dietary calcium, can be integrated into a single theoretic construct.

Is calcium more important than sodium in the pathogenesis of essential hypertension?

The hypothesis that abnormalities of calcium homeostasis at both an organ and cellular level are a primary factor in the pathogenesis of human and experimental hypertension forms the basis of this review. The rapidly expanding data base relating disordered calcium metabolism to altered vascular smooth muscle function and increased peripheral vascular resistance is summarized and integrated with the observations that reduced dietary calcium intake is the most consistent nutritional correlate of hypertension in the United States. The role of sodium and sodium chloride in pathogenesis of hypertension is reassessed in the light of new data from epidemiological clinical research, experimental models, and cell physiology investigations. The data supporting the thesis that the effects of sodium or chloride or both on blood pressure may represent, in selected situations, secondary influences mediated through induced changes in calcium homeostasis are presented. The interface between these nutritional factors and the normal regulation of vascular smooth muscle is discussed, providing a theoretical framework in which to assess the current information and to formulate the necessary future research.